Graduate Theses

abstract
Killer whales (Orcinus orca) play an important role in the coastal ecosystems of British Columbia. In recent decades, west coast transient and southern resident killer whales (two of the main ecotypes of killer whales in BC) have changed their use of coastal BC waters. However, seasonal abundance and distribution changes, and reasons for why the changes occurred remain relatively unknown. I used sighting reports of transient and southern resident killer whales from 2016-2023 in the inside waters of Vancouver Island (the Salish Sea and North Island Waters) to evaluate how these ecotypes use the area, and the relative importance of the area to their populations. I determined the proportion of the BC west coast transient killer whale population that use the inside waters and compared these results with southern resident killer whale seasonal variation in occupancy to analyze the difference in use of the Salish Sea between the two ecotypes. I found that approximately 70% of the BC west coast transient population uses the inside waters annually. Transient killer whales were present in the inside waters year-round, with seasonal highs from March-September each year, which corresponded with the presence of prey species that are drawn to the area during times that key fish species spawn. I also discovered an odd vs. even year pattern in transient killer whale presence where transient abundance varies in July of alternating years, which may be related to the return of pink salmon. Southern residents were not observed consistently throughout the year in the Salish Sea and had a fluctuating seasonal presence that peaked in March, July, September and November. These peaks also corresponded with spawning times of key fish species that southern residents rely on for prey. Overall, my results show that the inside waters of Vancouver Island are important for both ecotypes of killer whales, and that their presence in the area relates to spawning seasons of key fish species. These findings contribute to the conservation of west coast transient and southern resident killer whales and highlights the need to maintain the health of the inside waters.

abstract
Marine mammals routinely travel vast distances across the oceans, but there is ongoing debate on how they manage these feats. The typical approach to investigating how animals navigate involves first identifying a specific cue or environmental correlate that may influence their decisions, and then looking for behavioural evidence to support this hypothesis. However, selecting a cue to investigate without a priori knowledge of an animal’s movements can be inefficient and lead to confirmation bias. Therefore, I set out to demonstrate how a meta-analysis that identifies movement patterns in previously collected data is a valuable tool to generate useful hypotheses in navigation research. I illustrate this process using telemetry data from the Antarctic fur seal (AFS; Arctocephalus gazella), a model species due to its extensive at-sea movement and the vast amount of existing publicly available location data spanning two decades. The data was pre-processed to split journeys into outbound and inbound transiting periods whilst discarding intermediary foraging behaviour. In total, reliable data was obtained from 86 individuals from Marion Island and 132 individuals from Bird Island for my analyses. I then deployed four different approaches to quantify potential patterns in their movement to ultimately determine how they navigate. Circular statistics identified consistent preference for island-specific dispersal direction during outbound legs from their home island, as well as similarities between outbound and inbound directions. Area analysis identified potential corridor usage during return legs suggesting regular travel routes that can be potentially used to identify environmental cues. Block design statistics showed the seals’ ability to gradually correct their heading during inbound legs to the island. However, I did not find any correlation between lunar fraction and the timing of the start of these return legs. This study with AFS also provides a demonstration of how clearly delineating patterns in movement will permit unbiased testing of environmental correlates to determine how marine mammals navigate. For marine mammals in general, this research illustrates the importance of meta-analyses as an efficient, informative approach to analysis decision-making.

abstract
Biologging tags that record high-resolution tri-axial accelerometry data are proving to be integral to the study of foraging ecology of large, free-roaming marine mammals, such as whales. They have been applied to a number of baleen whale species that feed pelagically through lunges or ram filtration to quantitatively define behaviours and estimate energetic costs. However, few behavioural ecology studies using accelerometry data have been conducted on grey whales, a unique baleen whale that performs benthic suction feeding. Using suction cup tri-axial accelerometer tag deployments on 10 Pacific Coast Feeding Group (PCFG) grey whales along the Oregon and Washington coasts, I defined signals of foraging behaviour at both the broad state (dive) and foraging tactic (roll event) scales. I then estimated the relative energetic cost of these behaviours using energy expenditure proxies derived from the accelerometry data—Overall Dynamic Body Acceleration (ODBA; ms-2), stroke rate (Hz), stroke amplitude (radians per s), and duration of dives with different foraging tactics performed (min). Hidden Markov Models (HMMs) defined three biologically distinct states—forage, search, and transit—using turn angle, dive duration, dive tortuosity and presence of roll events. Classification and Regression Tree (CART) models best defined the foraging tactics of headstands, benthic digs, and side swims using median pitch, depth to body length ratio, and absolute value of the median roll. These definitions of grey whale foraging signals using accelerometry data add to the quantitative descriptions of foraging behaviours previously described for baleen whales. Stroke rate identified foraging and headstanding as being the most energetically costly activities at the broad state and foraging tactic scales. These findings contribute to the foundational understanding of grey whale foraging energetics needed to assess the impacts of various conservation concerns on the fitness and interpret patterns of behaviour choice of this unique group of grey whales.

abstract
Eastern North Pacific grey whales (Eschrichtius robustus) rely on energy reserves obtained on their northern feeding grounds to complete their annual 17,000 km round-trip migration between the Arctic and Mexico. However, estimates of how much food is required to complete the annual migration is limited to adult whales of average size, and is not readily available across all age classes of males and females. I constructed an age-structured bioenergetics model using detailed information on the grey whale life cycle and migration timings to predict the energy requirements of different cohorts of grey whales. Results show that nursing calves require 24–35 L of milk daily in their first 9 to 10 months. Once weaned, juveniles require ~345 kg day-1 of benthic invertebrates (4.5% of body weight), while the largest adult whales will need a minimum of ~870 kg day-1 (4.3% of body weight) during the ~5 month (154 days) summer foraging season in the Arctic. In contrast, pregnant individuals need 1,630–1,969 kg of prey day-1 (9.3–10.3% of body weight) during this same period to support foetal growth and store sufficient energy to produce milk once the calves are born in Mexico. Lactating whales returning to the Arctic with their calves will require 1,360–1,960 kg of prey day-1 (8.2–8.9% of body weight) over the next 4.5 months to continue producing milk. My results can be combined with measured densities of benthic prey in the Arctic to assess and anticipate the likelihood of climate change or conspecific competition causing starvation-related mortality of grey whales in the future. My age-structured bioenergetics model is simple and flexible enough to adapt to any migratory species of interest, including rare, endangered species that may otherwise be considered data deficient.

abstract
The global population of California sea lions (Zalophus californianus) has declined in the Gulf of California (Mexico), while numbers have increased along the California coastline (U.S.). It is unclear what is behind the divergent population trends, but differences in diets likely play a role. I used diet data to investigate whether the changes in sea lion population numbers that occurred in sea lion numbers from 1980–2020 could be explained by differences or shifts in diet quality — specifically energy density and diet diversity. I also explored whether diet quality in the Gulf of California was affected by increased sea surface temperatures that occurred in 2014. I considered rookeries in California (Channel Islands) to be a single ecological Zone and divided the Gulf of California breeding islands into nine Zones based on geographic proximities and similarities in population trajectories. Years with matching population and diet data within all these Zones were used to test for relationships between measures of diet quality and population changes. My results showed that diet variability and composition differed between the Channel Islands and the Zones within the Gulf of California. In general, sea lions breeding in the Gulf of California consumed a large variety of mostly benthic species and schooling fish, whereas sea lions at the Channel Islands primarily consumed schooling fish and squid. Contrary to expectations, no significant relationships were found between population changes and measures of diet quality across all Zones and times. However, the average energy density of sea lion diets in certain Zones within the Gulf of California declined as sea surface temperatures increased. While my results did not reveal a direct relationship between population changes and diet quality, they demonstrate the significance of considering the influence of environmental heterogeneity on regional population dynamics. My results also highlight the importance of better understanding the ecosystem dynamics of the Gulf of California at small regional scales. Such findings may be key to fully understanding the interplay between environmental changes, diets, and future population trajectories of California sea lions and other pinniped species in geographic locations throughout Mexico and the U.S.

abstract
Populations of Chinook (Oncorhynchus tshawytscha) and coho salmon (O. kisutch) have experienced significant declines in abundance and productivity over the last 50 years in the Salish Sea as harbour seals (Phoca vitulina) recovered from hunting and culling. Some have hypothesized that increased predation by seals may be responsible for the declines in salmon survival, and their failure to recover after reductions in fishing effort. However, it is not known if these correlations exist for every population of salmon in the Salish Sea, or how many young Chinook and coho salmon are consumed by seals each year. I developed mathematical and statistical models to investigate the potential causal relationship between seal predation and declines in Chinook and coho salmon populations in the Salish Sea. I also used simulation modeling to evaluate outcomes that may result if managers reduced British Columbia’s harbour seal population to promote the recovery of salmon populations. I found that harbour seal densities were strongly negatively associated with productivity of most wild Chinook salmon populations in the Salish Sea and Washington Coast that were included in the study. Integrating recently collected seal diet data with a novel predation model indicates that large numbers of juvenile Chinook and coho salmon are eaten by seals, and that predation-related mortality has likely increased significantly over the last 50 years. The results of my simulation model suggest both lethal removals and contraception could reduce the seal population, but that important tradeoffs exist between the two approaches. Overall, my findings increase understanding of the role that marine mammal predation plays in the early marine life stage of juvenile salmon, and identifies potential outcomes and tradeoffs of actively managing predator populations.

keywords     predation, harbor seal, salmon, coho, Chinook, culling, hunting, modelling, hatcheries, diet, contraception, juvenile salmon, smolts, management

abstract
An array of foragers prey on salmon in rivers and estuaries while salmon smolts out-migrate from their natal streams-and may account, in part, for the poor returns of adult salmon to the Salish Sea. However, the Pacific great blue heron (Ardea herodias fanning) has not been identified as a predator of smolts despite being regularly seen near salmon streams. I investigated the role that herons may be playing in the depredation of salmon by scanning fecal remains under heron nests for Passive Integrated Transponder (PIT) tags that had been implanted in wild and hatchery-reared salmon smolts from 2008-2018. These nests were located in three heron rookeries that were within 35 km of the mouth of the Cowichan, Big Qualicum, and Capilano Rivers. Using a mobile PIT antenna, I recovered 1,199 smolt tags, representing a minimum annual predation rate of 0.3-1.3% of all smolts in the three rivers. Correcting for tags consumed by herons and defecated outside of the rookery raised the estimated proportion of smolts to 0.7-3.2% of the outmigrating fish, but predation rates as high as 6% were documented during a low river-flow year in the Cowichan River. The distribution and timing of tag depositions under the heron nests indicated that most great blue herons prey on salmon smolts and that consumption occurs in late spring during the chick-rearing phase of the breeding season. Energetic analyses suggest that smolt consumption provides a substantial proportion of the heron chick diet during a time of peak energy demand. Predation on smolts occurred primarily in the lower rivers and upper estuaries. Smaller salmon smolts were significantly more susceptible to heron predation in all systems, and predation rates were comparable between wild and hatchery-reared smolts. Recovering so many tags from smolts at heron rookeries was unexpected and indicates that great blue herons are a new predator of wild and hatchery-reared juvenile salmon. Locations of heron rookeries relative to salmon bearing rivers are likely good predictors of heron impacts on local salmon runs, and a potential means to assess coast-wide effects of great blue herons on salmon recovery.

abstract
Marine mammal diving behaviour is influenced by multiple physiological processes, both at depth and at the surface. To date, the majority of research in diving physiology has focused solely on how quickly marine mammals utilize their O2 during a dive, as seen in the numerous studies of the aerobic dive limit (ADL) and calculated aerobic dive limit (cADL). In this thesis I investigated other physiological limits, namely how long it takes for marine mammals to recover after a dive, and how these animals transition between aerobic and anaerobic metabolism at depth. Specifically, I 1) determined how post-dive rates of O2 and CO2 gas exchange are affected by dive behaviour, and 2) measured how lactate accumulates with increased dive time, and examined how this indicator of metabolic transition affected post-dive recovery times. To measure gas exchange, I used flow-through respirometry to determine the time required for Steller sea lions (Eumetopias jubatus) to reach within 5% of stable rates of O2 uptake and CO2 excretion following a dive. These times were interpreted as the O2 and CO2 recovery times, respectively. CO2 recovery time was longer and became more extended with increasing dive time when compared to O2, requiring an extra 44 sec per minute submerged for CO2 as opposed to 33 sec per minute submerged for O2. This indicates that recovery time was limited by CO2 as opposed to O2, and this difference became greater with increased dive time. Contrary to traditional models, plasma lactate concentration was present even after short dives, and increased linearly with dive duration. Neither O2 nor CO2 recovery rates were affected by levels of blood lactate. This indicates that anaerobic metabolism may be used long before the body’s total O2 stores have been consumed. These results support the idea that there is not a distinct threshold between aerobic and anaerobic pathways, but rather a progressive transition, which casts doubt on the usual interpretations of the ADL and cADL. My thesis challenges long-held assertions in diving physiology, and underlines the need to further examine how CO2 and lactate accumulation may act as limits to diving behaviour.

keywords     Steller sea lion, metabolism, foraging

abstract
The hearts of marine mammals frequently sustain marked changes in heart rate and vascular resistance when diving. However, it is not known how marine mammal hearts facilitate these changes. I examined cardiac function and electrical activity of marine mammal hearts to understand how they might differ from terrestrial mammals. I measured electrocardiographic parameters in 8 Steller sea lions, 5 northern fur seals, and 1 walrus-and echocardiographic function in all 8 Steller sea lions. I also compiled electrocardiographic parameters from 17 species of marine mammals (including my measurements) for comparison with 50 species of terrestrial mammals. I found that atrial and ventricular depolarization are slower in marine mammals after accounting for differences in body mass-and that the left ventricle of Steller sea lions contracts less than expected for a mammal of that size. These differences in cardiac timing and function may reflect specialized adaptations for diving. Electrocardiographic measurements of Steller sea lions, northern fur seals, and a walrus also varied between species and among the individuals of each species. For example, sinus arrhythmias occurred in 5 out of 8 individual Steller sea lions, but not in northern fur seals or the walrus. Mean electrical axes were also unique to each individual and varied greatly. Measurements ranged from -124° to 80°-with 3 of the Steller sea lions having extreme right axis deviation (-111° to -124°). Echocardiographic measurements showed that left ventricular form was similar between Steller sea lions and terrestrial mammals, except that Steller sea lions have larger aortic roots and larger left ventricular end-systolic dimensions than terrestrial mammals. Overall, my results show that marine mammals have functionally similar hearts to terrestrial mammals with a number of notable differences that likely support anatomical adaptations to diving.

abstract
There is increasing evidence that predation by harbour seals (Phoca vitulina) on young salmon (smolts) out-migrating from rivers may be a significant source of mortality for coho (Oncorhynchus kisutch) and Chinook (O. tshawytscha) salmon populations in British Columbia. Studies supporting this have focused on documenting what and how much harbour seal populations eat - and the potential impact this has on salmon populations. However, little attention has been given to understanding where, when and how this predation occurs, and the extent to which it might be opportunistic or specialist feeding behaviour by a few or many individual seals. I documented the spatiotemporal foraging behaviour of harbour seals in the Salish Sea by equipping 17 seals with GPS loggers and Daily Diary tags - and tracking them before and after the release of thousands of coho and Chinook smolts from the Big Qualicum Hatchery. Reconstructing the high-resolution movements of the seals - and quantifying feeding using counts of prey chasing events (PCEs) detected by accelerometry - revealed that the Big Qualicum estuary was a feeding hotspot for 47.0% of the 17 tracked seals, but was relatively small geographically (accounting for 3% of PCEs) compared to the largest feeding area outside the estuary (26% of PCEs). Comparing the foraging behaviours of smolt specialists with non-specialist seals revealed 4 different foraging strategies. One consisted of seals (17.6%) that only fed on coho smolts and ignored Chinook in the river mouth, while a second group of seals (17.6%) appeared to target larger fish that preyed on Chinook smolts near the river mouth. The two other seal groups did not feed at the river mouth in association with the concentrated numbers of smolts, but either remained resident (52.9%) and fed near their main haul-out sites, or were transient (11.8%) and left the study area all together. My results suggest a high degree of individual foraging and diet specializations - and show that a small number of seals were specialized in consuming coho smolts, but did not appear to respond to the large pulse of the smaller bodied Chinook smolts. Such information concerning the fine-scale foraging behaviour of harbour seals in relation to pulses of out-migrating smolts can be used to design mitigation strategies to enhance coho and Chinook populations.

abstract
Bioenergetic studies can quantify the conversion of chemical energy contained in food to biologically useful energy to understand how changes in diet quality and quantity affect overall energy budgets and nutritional status. However, chemical energy is intrinsically linked to the macronutrients contained in food (i.e., lipid and protein) in terms of energetic density and digestive efficiency. For northern fur seals (Callorhinus ursinus) it is unknown how efficiently they transform dietary gross energy to net energy. I fed six trained adult female fur seals eight experimental diets composed of four prey species (capelin, walleye pollock, Pacific herring, and Magister squid), alone or combined. I measured the fur seals' digestive efficiency for energy and macronutrients across diets. I also investigated the effect of dietary intake on digestive efficiency, and tested the hypothesis that mixed-species diets provide a greater nutritional return than equivalent single-species diets. I quantified net energy uptake by measuring excreta energy loss and measuring heat increment of feeding. My results revealed significant differences between digestive parameters across diets. I found that digestible energy (95.9-96.7%) was negatively affected by both ingested mass and dietary crude protein. Furthermore, urinary energy loss (9.3-26.7%) increased significantly with increases in dietary crude protein. I also found that the heat increment of feeding (4.3-12.4%) increased with decreasing dietary lipid content. Overall, net energy gain (57.9-83.0%) was positively correlated with lipid content. I found that macronutrient digestibility differed across diets and that, overall, lipids were more digestible (96.0-98.4%) than crude proteins (95.7-96.7%). Also, dietary protein influenced the ability of fur seals to digest lipids and proteins. Overall, my results demonstrate that low lipid prey not only contain less gross energy, but result in proportionally lower net energy gain following digestion, partly due to decreasing digestibility of lipids in high protein diets. I also found that, counter to predictions, mixed-species diets do not provide fur seals with greater energetic or macronutrient gains than single-species diets. These findings contribute to understanding the nutritional ecology of northern fur seals and the impact that changes in diet can have on the fur seals' nutritional state.

abstract
Air-breathing divers, such as marine mammals, should adjust their diving behaviours in relation to the depth and density of their prey to minimize the energetic costs and maximize the benefits of foraging. However, there is little experimental data to test these predictions or to develop models to predict the responses of marine mammals to changes in prey availability. The objectives of my study were to 1) determine how changes in prey availability affect dive behaviour and foraging efficiency in Steller sea lions (Eumetopias jubatus) and 2) develop models with data from free-diving captive Steller sea lions to estimate foraging costs in wild animals and evaluate energetic trade-offs between different foraging strategies. I measured the diving metabolic rate, dive durations, and food intake of 4 trained sea lions diving in the open ocean on simulated prey patches of high- or low-densities at 10 m and 40 m. I also measured diving metabolic rates of sea lions performing 4 controlled dive types that allowed me to estimate the separate costs of different dive components (i.e., surface time, bottom time, and transiting to and from depth). I found that animals diving on prey patches with low prey density altered their dive behaviours and spent proportionally less time actively foraging, which ultimately decreased their foraging efficiency. I also found that making single, longer dives were less energetically costly than making multiple shorter dives in a bout, but that the sea lions replenished oxygen stores more efficiently when making a bout of dives. Finally, I determined the metabolic cost of transiting to and from depth (20.5Ä…13.0 ml O2 min-1 kg-1) was greater than the cost of foraging during the bottom portion of a dive (13.5Ä…4.1 ml O2 min-1 kg-1). With these values, I generated a predictive equation to estimate the diving costs of free-ranging animals. Overall, my results indicate that Steller sea lions do alter their dive behaviour in relation to prey availability and that different foraging strategies have different energetic costs. These results can be used to understand how changes in prey availability affect the overall energy balance and health of Steller sea lions.

keywords     Steller sea lion, foraging energetics, diving physiology

abstract
Efficient extraction of energy from the environment is key to the survival and reproductive success of wild animals. Understanding the ratio of energy gained to energy spent of different foraging strategies (i.e., foraging efficiency) can shed light on how animals cope with environmental changes and how it affects population trajectories. I investigated how female foraging strategies during the breeding season impact the foraging efficiencies and reproductive successes of two fur seal species—one declining (NFS–northern fur seals, St. Paul Island, Alaska) and one increasing (AFS–Antarctic fur seals, Kerguelen Island, Southern Ocean). I also sought to develop new accelerometry-based methods to easily determine fine-scale energy expenditure at sea (VeDBA and flipper stroke metrics). Twenty lactating females of each species were captured and equipped with biologging tags to record GPS locations, depth and tri-axial acceleration. Energy expenditure for each foraging trip was measured using the doubly-labeled water method, and energy gained while foraging was determined from 1) diet composition (scat hard-parts and DNA) and blood stable isotope ratios; and 2) numbers of prey capture attempts (from head acceleration). Maternal investment in pups was determined from pup growth rates or from energy content of milk samples. Results showed acceleration metrics were only accurate at predicting energy expended by fur seals when time-activity budgets were taken into account (i.e., time spent performing different types of activity). Foraging strategies of AFS females resulted in efficiencies of ~3.4, with more efficient females producing bigger pups at weaning that had greater chances of survival. NFS females employed two foraging strategies with very different efficiencies (~1.4 vs. ~3.0) that were associated with different foraging habitats and diet qualities. However, NFS with the more efficient strategy (3.0) undertook longer foraging trips than the oth er NFS ( 1.4) or AFS (3.4), and thus fed their pups ~20% less frequently. As a consequence, the declining NFS (unlike the increasing AFS) had to compromise between the rate of energy acquisition and the pup feeding frequency. Such reductions in energy intake and time allocated to nursing pups can ultimately lower juvenile survival, and may explain the population decline of NFS in Alaska.

keywords     northern fur seals, St. Paul Island, Alaska, Antarctic fur seals, Kerguelen Island, foraging efficiency, foraging strategies, breeding season, reproductive successes, biologging, accelerometry, VeDBA, flipper stroke, doubly-labeled water, diet compos

abstract
Fin whales are acoustically active year-round, particularly during the winter breeding season when males produce song as a reproductive display. Little is known about movement patterns and population structure of the fin whale (Balaenoptera physalus) in the North Pacific. I used passive acoustic data recorded using bottom-mounted autonomous recording instruments to answer questions about the winter distribution, behaviour and population structure of fin whales in a high-latitude area of the eastern North Pacific Ocean. I found that fin whales are present in British Columbia (BC) waters throughout the winter, and their acoustic behaviour suggests that they are engaging in reproductive and possibly feeding behaviour. The presence of these individuals indicates that not all fin whales migrate south in the winter to low-latitude breeding grounds. I found that the majority of fin whales recorded in BC sang a doublet song with alternating ~13 s and ~17 s intervals between alternating classic and backbeat notes (song Type 2). At the most northerly recording site, and the two offshore sites, I found a few instances of a previously described doublet song type that has longer internote intervals (song Type 1). This suggests that two spatially segregated populations of fin whales are using BC waters, with the population producing song Type 2 being more coastal. Through a literature search, I found evidence of song Type 2 occurring from northern BC to Oregon. Song Type 1 has been documented off Southern California, the Bering Sea and the central North Pacific. My results are consistent with evidence showing that two genetically distinct fin whale populations occur in the eastern North Pacific, and that the population that produces song Type 2 is more closely related to the Southern Hemisphere subspecies of fin whale, than to the other population of fin whales in the North Pacific. My results show that BC waters are important for fin whales year-round, rather than just during the summer feeding season―and that the fin whales in BC likely belong to two distinct populations (one of which may belong to the Southern Hemisphere subspecies) and may require separate plans for their conservation and management.

keywords     passive acoustics, fin whale, distribution, behavior, population structure, reproduction, feeding, song

abstract
Harbour seals have long been perceived to compete with fisheries for economically valuable fish resources in the Pacific Northwest, but assessing the amounts of fish consumed by seals requires estimates of harbour seal diets. Unfortunately, traditional diet analysis techniques cannot provide the necessary information to estimate the species, life stage, and biomass of key prey (e.g. salmonids) consumed by seals. I therefore developed a new harbour seal diet analysis methodology, using scat DNA metabarcoding and prey hard-part analysis to create refined estimates of salmon in harbour seal diet. I also sought to understand the quantitative potential of DNA metabarcoding diet analysis (i.e. the relationship between prey biomass proportions and DNA sequence percentages produced by high-throughput amplicon sequencing of seal scat DNA). Analysis of faecal samples (scats) from captive harbour seals fed a constant diet indicated that a wide range of factors influence the nu mbers of prey sequences resulting from scat amplicon sequencing. These biases ranged from preferential amplification of certain prey species DNA, to sequence quality filtering—in addition to interactions between the various biases. I was able to apply correction factors derived from tissue mixtures of the species fed to captive seals that improved prey biomass estimates from DNA, and found that the lipid content of prey fish species perfectly predicted the magnitude of bias resulting from differential prey digestion. My results suggest that highly accurate pinniped prey biomass estimates can be attained by applying two stages of corrections to prey DNA sequence counts. However applying these corrections to the scats of wild seals is challenging, and requires a complete prey tissue mix library to create species-specific correction factors for all prey. While I established an approach that could be applied to wild seals, a thorough statistical evaluation and follow-up feeding studies are need ed to determine if the additional effort is justified for population level diet estimates. Lastly, I developed a decision tree approach for merging salmon DNA and hardparts data from seal scats to determine the species and life stages of salmon consumed by seals in the Strait of Georgia, British Columbia.

keywords     harbour seals, diet analysis, salmonids, scat, DNA metabarcoding, prey hard-part analysis, high-throughput amplicon sequencing, Strait of Georgia, British Columbia

abstract
Seasonal changes in the daily energy expenditure (DEE) of captive northern fur seals (Callorhinus ursinus) and key components of their energy budget (cost of resting metabolism, thermoregulation, activity and growth) were examined to elucidate potential reasons for the species’ population decline in the wild. The average DEE of 6 females was 527.8 ± 65.7 kJ kg-1 d-1 and fluctuated seasonally (~20% greater in the fall than in the winter). Resting metabolism also changed significantly with season, and was higher in the fall (potentially due to molting or as preparation for migratory activity). While resting metabolism was the largest component of the DEE (~80% on average), it did not follow the same seasonal trend as DEE, and therefore was not the source of the seasonal variation in DEE. Cost of activity was the second major component of DEE and may explain the observed seasonal variations. Energetic costs associated with thermoregulation appeared to be negligible. The northern fur seals were thermally neutral in all seasons for all water temperatures tested (2 °C – 18 °C), except during the summer when immersed in 2 °C water. Comparing this broad thermal neutral zone to the average sea surface temperatures encountered by fur seals in the wild during annual migrations indicates that fur seals can likely exploit a large geographic area without added thermal metabolic costs. While the direct energetic costs of growth appeared to be negligible compared to DEE, the higher growth rates in the summer and elevated resting metabolism in the fall suggests that inadequate nutrition could have greater negative effects during these seasons. Two alternative proxies for measuring energy expenditure were tested and calibrated against respirometry for potential application to wild individuals. The doubly labeled water (DLW) method over-estimated DEE by 13.1 ± 16.5% compared to respirometry. In comparison, accelerometry over-estimated DEE, using fine time scale intervals of 60 and 15 min, by an average of 5.4 ± 29.3% and 13.8 ± 39.5%, respectively. Importantly, seasonal effects (and time of day for accelerometry) must be accounted for when estimating energy expenditure from measures of DLW and acceleration in free-swimming northern fur seals.

keywords     Northern Fur Seal, Daily Energy Expenditure, Thermoregulation, Activity, Resting Metabolic Rate, Growth, Doubly Labelled Water, Accelerometry, Respirometry

abstract
The diving ability of marine mammals is limited by body oxygen stores (TBO) and rates of oxygen depletion (diving metabolic rate; DMR), which can be expressed as the calculated aerobic dive limit (cADL). Diving ability must also be influenced by CO₂ production and control of ventilation. I investigated the factors that limit the diving ability of Steller sea lions (Eumetopias jubatus), including the effect of nutritional stress on the cADL. Specifically, I 1) determined the cADL of Steller sea lions by measuring TBO and DMR, 2) determined whether nutritional stress alters the cADL and 3) examined the post-dive elimination of CO₂, and the sensitivity of Steller sea lions to hypercapnia (high inspired CO₂). TBO was estimated from measured blood oxygen stores and body composition―and metabolic rate, breathing frequency and dive behaviour were recorded prior to and during a period of nutritional stress where animals lost ~10% of their mass. Animals breathed ambient, hypercapnic or hypoxic (low O₂) air to experimentally alter pCO₂ levels and decrease rates of CO₂ elimination and O₂ consumption. I found that the TBO (35.9 ml O₂ kg-¹) and cADL (3.0 minutes) in actively diving Steller sea lions were lower than previously reported for other species of sea lions and fur seals. I also found a significant increase in mass-specific DMR and blood volume (resulting in higher TBO) in nutritionally stressed animals that resulted in a longer cADL. Hypercapnia was found to significantly affect ventilation, but had no effect on dive behaviour―and elimination of CO₂ between dives took longer than replenishing O₂ stores. Overall, nutritional stress and hypercapnic conditions did not directly limit the diving ability of the Steller sea lions, but had an indirect effect on foraging efficiency by increasing the time they spent on the surface between dives. Accumulation of CO₂ over several dives in a foraging bout also appeared to reduce foraging efficiency, which likely ultimately limits the time a sea lion spends in apnea and therefore overall foraging duration and net energy intake.

abstract
Assessments of distribution and abundance are a common means of gauging impacts of anthropogenic activities on wildlife. However, the influence of behavioural responses on estimated numbers and distributions of animals is rarely considered within this context. I used behavioural data collected in the Beaufort Sea from 1980-2000 to investigate the effects of seismic operations on the distribution and abundance of bowhead whales (Balaena mysticetus). Bowhead whales are known to vary their dive and surface-respiration behaviour when exposed to seismic survey operations, although it is unknown whether these changes in behaviour differ by season, reproductive status and activity (feeding, socializing and travelling). Overall, I found that changes in behaviour of whales exposed to seismic operations were context dependent (i.e., they were contingent on the whale’s circumstance and activity). I then investigated the effects of these behaviour changes on the sightability of whales to aerial observers conducting line-transect surveys. I calculated and compared sightability correction factors specific to whales exposed and not exposed to seismic operations and found that whales in all circumstances were less available for detection when exposed to seismic sounds. In particular, non-calves were the least available to observers during autumn when exposed to seismic activities, regardless of activity state. I used line-transect distance sampling and spatial modeling methods to generate corrected density estimates for bowhead whales in an area of the southern Alaskan Beaufort Sea ensonified by seismic operations between late August and early October 2008 to investigate the extent to which density analyses were affected by changes in whale availability. The resultant density surface models revealed a wide-spread nearshore distribution of whales within the ensonified area with some spatial segregation related to activity state. Density estimates that accounted for variations in whale behavior due to seismic operations were also 25–64 % higher than previous estimates. Collectively, these findings suggest that seismic activities may not have displaced bowhead whales as previously thought, but altered their dive behaviours instead ,making them less visible for counting. My research demonstrates the importance of accounting for behavioural reactions when assessing impacts of seismic operations on distributions and abundances of whales.

keywords     bowhead whale, behaviour, seismic testing, distribution, disturbance, abundance, Beaufort Sea, Arctic

abstract
Foragers with narrow dietary niches often exhibit specialized hunting behaviours that improve their efficiency for capturing preferred prey, but can leave them vulnerable if the abundance of this prey declines. I examined the specificity of foraging behaviour by a highly selective predator, the northern resident killer whale (Orcinus orca), which specializes on Chinook salmon (Oncorhynchus tshawytscha). Northern residents are undoubtedly well adapted to capture Chinook, however, their hunting tactics have never been described due to the challenges of quantifying underwater behaviour. To address this research gap, I deployed archival tags (DTAGs) on 32 killer whales to measure their acoustic and kinematic behaviour during foraging dives. Reconstructed 3-dimensional tag tracks indicated that foraging and non-foraging dives were kinematically distinct. While engaged in hunting behaviour, whales dove deeper, remained submerged longer, swam faster, increased their dive path tort uosity, and rolled their bodies more than during other activities. Maximum foraging dive depths reflected both the deeper vertical distribution of Chinook (compared to other salmonids), as well as the tendency of these fish to evade predation by diving steeply. Inferences from whale movements further revealed that salmon engaged in other anti-predation strategies, including increasing swim speeds and evasive manoeuvring. DTAG records also provided the first definitive link between echolocation and prey captures by resident killer whales, who displayed significantly higher clicking rates and spent proportionally more time echolocating prior to capturing a fish than they did afterward. Rapid ‘buzz’ click sequences were often produced before fish captures, which is consistent with their hypothesized function of close-range prey targeting. Furthermore, prey handling ‘crunches’ were usually detected following kills and, with buzzes, provide possible acoustic proxies for capture attempts and successes that could be used to estimate foraging efficiency. My thesis determined that northern resident killer whales possess specialized foraging behaviours for targeting Chinook salmon. The specificity of these behaviours may make the whales less effective at capturing other types of fish. If northern residents have limited flexibility to modify their foraging behaviour to successfully exploit other prey types when Chinook availability is reduced, prey capture efficiency (and thus per capita energy intake) could decline.

keywords     prey capture, northern resident, DTAG, salmon

abstract
The core breeding population of northern fur seals (Callorhinus ursinus) in North America has declined significantly since the 1980s on St. Paul Island (one of the Pribilof Islands) while the smaller nearby population at Bogoslof Island (eastern Bering Sea) has increased exponentially. Further south, the population of northern fur seals on San Miguel Island off the coast of Southern California has fluctuated between exponential growth and catastrophic declines associated with re-occurring El Nino events. The goal of my thesis was to asses the physiological status of these three breeding populations of northern fur seals in North America to determine whether nutritional differences could explain the different population trajectories. I collected fecal samples (scats) in July 2009 from these three islands and measured the fecal metabolites of two hormones ˜ a glucocorticoid associated with the stress response, and triiodothyronine (T3), a thyroid hormone associated with metabolic rate. I also assessed feeding conditions using diet and foraging data. I found that sub-adult males and lactating females on St. Paul Island experienced poorer feeding conditions (lower energy content food and longer feeding trips for lactating females) than at Bogoslof Island, but that only the females were nutritionally stressed. I also found that the San Miguel Island population differed physiologically compared to the northern populations in Alaska in terms of stress and nutritional status. The San Miguel fur seals were the most physiologically stressed of the North American fur seal populations (based on elevated levels of glucocorticoid metabolites). However, the stress was most likely related to heat stress and not food (based on low concentrations of T3 metabolites). The available hormone, diet, and foraging data from northern fur seals in North America suggest that lactating females were nutritionally stressed on St. Paul Island and heat stressed on San Miguel Island, and experienced better conditions on Bogoslof Island.

abstract
South American fur seals (Arctocephalus australis) continue to survive in Peru in spite of commercial harvesting, periodic disappearance of prey (i.e., El Niño), and competition with the Peruvian anchoveta fishery. I investigated the ability of the Peruvian population of fur seals to recover from catastrophic declines at two temporal and spatial scales. The first analysis determined intrinsic rate of growth (r) and the potential carrying capacity (K*˜the number of fur seals that could be supported in Peru in the absence of sealing and El Niño) from 1880ˆ2010, and the second used pup counts from 1984ˆ2010 to determine the relationship between prey abundance and the timing of pupping at an important fur seal breeding site in southern Peru. Model results indicated that South American fur seals in Peru have an intrinsic growth rate r of 0.20 and a potential carrying capacity K* of 115,000 seals. Recent counts (2007) show that current population is at 33% of the estimated mean numbers of fur seals alive from 1880-1925. Analysis of 25 years of counts of pups and adult females at the breeding site showed a correlation between anchoveta biomass and mean birth dates (r2 = 0.59, P<0.01) and with the ratio of pups to females (r2 = 0.66, P<0.01) in the upcoming breeding seasons. It also revealed a 2-week shift in the mean birth date that may reflect a change in the age structure of the population. Numbers of pups born tended to be lower in years with low anchoveta biomass, as did recruitment of young females. Monitoring daily numbers of pups born and adult females appears to be a useful means to assess the feeding conditions encountered by South American fur seals in Peru. My study also suggests that South American fur seals are adapted to survive in extremely disturbed environments and have the potential to rapidly recover following population declines. Whether or not they ever again achieve their potential carrying capacity will depend upon protection of breeding rookeries, a continued harvest ban, reduced bycatch, incidental captures and illegal poaching, regulation of anchoveta fishing quotas and good environmental conditions.

keywords     population dynamics, prey abundance, anchoveta, Peru, South American fur seals, pup production

abstract
Management plans for North Atlantic right whales (Eubalaena glacialis) focus on preventing mortality from ship strikes and fishing gear entanglement. However, population recovery may also be limited by nutritional stress. I derived growth curves and quantified the food requirements of North Atlantic right whales by age, sex and reproductive state. I also compared their predicted needs with field estimates of prey consumption to evaluate the model predictions and consider whether different demographic groups of right whales might be nutritionally stressed. Energy requirements were estimated using a bioenergetics model that incorporated uncertainty in energy inputs and outputs. Consumption was estimated with prey samples taken near feeding whales in two critical feeding habitats˜Cape Cod Bay (n=28 net collections) and the Bay of Fundy (n=19 optical plankton counts). Model predictions indicate that mothers invest heavily in their calves, which effectively double in size and attain ~73% of their mother‚s length by weaning at one year of age. Calves gained an average of ~1.7 cm and ~34 kg per day while nursing during this rapid growth phase. Body growth was best described using a two-phased Gompertz model and could not be fit using any of the single continuous growth models commonly used for other mammals. Energetically, calves required the least energy (~1129 MJ/day) and lactating females required the most (~2934 MJ/day). Adult males and non-reproductive females fell in between at ~1140 and ~1217 MJ/day respectively. Estimates of energy requirements for juveniles, adult males, pregnant and non-reproductive emales compared favorably with estimates of actual prey consumption in their winter habitat (i.e., they differed by ≤15%), suggesting that the model was reliable. However, lactating females appear to obtain considerably less (~45%) of their predicted daily energy requirements in Cape Cod Bay, and almost met their needs in the Bay of Fundy (obtaining ~87% of daily requirements). This suggests that lactating females may be experiencing an energy deficit, which may affect reproductive rates and slow population recovery. Nutritional stress may thus be limiting the recovery of North Atlantic right whales.

keywords     North Atlantic right whale, nutritional stress, energetics, prey consumption, growth

abstract
Habitat characteristics and mechanisms that enable predators to successfully forage are poorly understood in open marine ecosystems. I addressed this problem in the eastern Bering Sea using animal-born data-loggers carried by lactating northern fur seals (Callorhinus ursinus) from two populations breeding in distinct oceanographic zones ˜ a declining population on St. Paul Island on the continental shelf, and an increasing population on Bogoslof Island over the oceanic basin. The data-loggers recorded water temperatures, dive depths and animal locations throughout foraging trips that lasted as long as 17 days and extended as far as 460 km from the islands. I contrasted tag-derived ocean temperatures with concurrent shipboard measurements and found that the fur seal data revealed finer-scale hydrographic processes with less estimated error than ship-derived data, particularly in dynamic oceanographic areas. I also identified probable foraging hotspots using first-passage time analysis of at-sea locations of individual females, and linked them to fine-scale hydrographic data using habitat selection models. I found that hot spots were related to thermoclines and surface fronts (although not with water temperature), and that the relationships differed between populations and among foraging strategies. St. Paul Island fur seals that mixed epipelagic and benthic dives focused their effort in areas with deeper thermoclines that may concentrate prey closer to the ocean floor, while strictly epipelagic foragers tended to use waters with shallower thermoclines allowing prey to migrate closer to the surface. Fur seals from Bogoslof Island foraged almost exclusively over the Bering Sea basin and appeared to hunt intensively along the fine-scale fronts that surrounded the island while fur seals from St. Paul Island extended their trips off-shelf to forage in areas with similar oceanographic features. It appears that lactating females rely on fine-scale boundaries in the open ocean to effectively concentrate prey, and that the relative distribution and accessibility of these oceanographic features account for the inter-island differences in foraging patterns. Collectively, my thesis shows that wide-ranging, diving animals such as fur seals can be used to produce detailed maps of marine habitat and demonstrates the importance of fine-scale habitat characteristics to top predators foraging in dynamic oceanographic environments.

abstract
Pacific white-sided dolphins (Lagenorhynchus obliquidens) are one of the most abundant cetaceans in British Columbia and throughout the North Pacific Ocean. However, little is known about their seasonal distributions and energy requirements. I analyzed sightings of dolphins attained opportunistically by volunteer observers and from scientific surveysËœand found that Pacific white- sided dolphins have been seen with increased frequency along the BC coast over the past 54 years, and seasonally over the past 8 years. The sightings data showed a southward range shift from the 1950s to 2010, and a seasonal movement from offshore to nearshore waters concurrent with the timing of the herring spawn on the BC coast. I deduced whether seasonal movements reflect seasonal shifts in energy requirements by measuring resting metabolic rates and total energy intake for three captive white-sided dolphins twice per month for one year. Open-circuit gas respirometry revealed relatively high resting metabolic rates (~30 MJ day-1 or ~0.3 MJ kg-1day-1) suggesting that white-sided dolphins may need high-energy prey to fuel their energetic requirements. Average resting metabolic rates of the three dolphins were constant throughout the year despite an increase in food consumption in the fall (October to December). I used these average resting metabolic rates and other parameters associated with growth, activity and assimilation efficiency to inform a generalized bioenergetic model and estimate the food requirements of Pacific white-sided dolphins globally, regionally, and locally. My bioenergetic model predicted that wild dolphins require ~30 MJ day-1 for calves, ~60 MJ day- 1 for juveniles, ~65 MJ day-1 for adults and pregnant females, and ~90 MJ day-1 for lactating females. These energy requirements are ~50% higher than observed for dolphins fed in captivity, and are generally higher than estimates for other similar sized small cetaceans inhabiting temperate waters. My model predicts that an average sized dolphin (78 kg) in the wild would consume ~10 kg of fish per day, or about 13% of its bodyweight. Pairing information about prey requirements and seasonal distributions of dolphins with fisheries data can be used to assess spatial overlap between dolphins and fisheries, and may assist in reducing entanglement, by- catch, and conflict over prey.

keywords     energetics, dolphin, cetacean, food intake, metabolism, distribution, British Columbia, prey

abstract
Behavioural observations are fundamental to understanding and defining the habitat needs of animals. I compiled the behavioural repertoires reported for harbour (Phocoena phocoena) and Dall’s porpoise (Phocoenoides dalli) by classifying the life processes of phocoenids into 12 descriptive categories. This range-wide review revealed complex sexual and social behaviours, similar foraging behaviours and breeding site fidelity, as well as differences in habitat selection between these two northern hemisphere species. I also conducted a fine-scale field study of harbour porpoise foraging behaviour at two sites in Juan de Fuca Strait (British Columbia) using point transect survey data (2007–2008), and platforms of opportunity data (1995–1996, 1998–2008) to determine the physical conditions under which harbour porpoise foraged and the extent to which they displayed specialised behaviours. I examined harbour porpoise presence, density and group sizes relative to tidal currents, tidal variation, lunar phase, lunar position, solar position, diurnality, seasonality and presence of conspecifics—and found that greater numbers of harbour porpoise occurred on the ebb current during the spring tides. Numbers of porpoise increased three-fold between April and October, when calves and high-energy behaviours were also more prevalent. To identify porpoise breeding habitat in the inland waters of southern British Columbia and northwestern Washington, I used systematically and opportunistically collected sightings of harbour and Dall’s porpoise (1991–2008), and compared group sizes and frequency of occurrences for both species relative to bathymetry and tidal speeds. Overall, I found that both species selected bathymetrically differentiated habitats that were characterized by high rates of tidal mixing (with harbour porpoise preferring regions ≤100 m, and Dall’s porpoise preferring 151 – 250 m). Spatial analysis identified two separate areas that may be species-specific breeding habitats—the first to be identified for either species in this region. In summary, harbour porpoise maintained stable group sizes and used tidally well-mixed foraging sites on a temporary but predictable basis. Dall’s porpoise were associated with these same areas, but habitat partitioning associated with differences in bathymetry occurred in important breeding areas that may account for the coastal parapatric distribution of these two high trophic level predators.

abstract
A leading hypothesis to explain the decline of Steller sea lions (Eumetopias jubatus) in western Alaska is the reduction of prey abundance or change in prey distributions caused by commercial fisheries. We sought to improve on past studies that attempted to assess competition between sea lions and fisheries by estimating the local amounts of prey accessible to sea lions. We explored the relationships between sea lion population trends, fishery catches and the prey biomass accessible to sea lions around 33 rookeries from 2000-2008. We focused on three commercially important species that dominate the sea lion diet: walleye pollock, Pacific cod and Atka mackerel. We estimated available prey biomass by removing fishery catches from predicted prey biomass distributions in the Aleutian Islands, Bering Sea and Gulf of Alaska; and modelled the likelihood of sea lions foraging at different distances from rookeries (accessibility) using satellite telemetry locations of tracked animals. We combined this accessibility model with the prey distributions to estimate the prey biomass accessible to sea lions by rookery. For each rookery, we compared sea lion population change to accessible prey biomass (estimated using our accessibility model and also within 10, 20 and 50 km of each rookery). Of the 304 statistical models we constructed to compare accessible prey biomass and catch to sea lion population trends, only three relationships were significant. These three suggest that sea lion population change rates increased (became less negative) with increasing accessible pollock biomass in the Aleutian Islands and with cod biomass in the Gulf of Alaska. No relationships were found between sea lion population trends and Atka mackerel biomass. Given that the majority of the relationships we explored were insignificant, it seems unlikely that the availability of pollock, cod or Atka mackerel was limiting sea lion populations in the 2000s. Sea lion population trends appeared to be affected by some unknown factor associated with regional differences. Removing fish catches or adding catch to our predicted distributions of groundfish abundances had no measurable effect on sea lion population trends. These observations suggest that sea lion populations were largely unaffected by fishery removals during this period.

abstract
Knowing how species will respond to environmental variability and climate change requires understanding the factors that influence their distribution and movement patterns. I investigated the processes that drive individuals to concentrate in specific areas of their home range by modeling encounter rates of humpback whales (Megaptera novaeangliae) in relation to environmental variables using GIS tools, generalized additive models, and remote sensing and in situ data. I conducted this work at two foraging areas: the coastal waters of British Columbia, Canada, and the Bransfield and Gerlache Straits, Antarctica. Humpback whales in British Columbia were strongly associated with latitude and bathymetric features. The relationships with remotely sensed variables reflecting primary productivitywere not consistent, but higher numbers of whales seemed to be associated withhigherproductivity. In fact, the highest concentrations of humpback whales appeared to reflect areas whereconcentration and retention processes lead to higher biological productivity, including south Dixon Entrance, middle and southwestern Hecate Strait and off Juan de Fuca Strait. Humpback whales in the Southern Ocean also preferred areas of enhanced biological productivity. In Gerlache Strait, humpback whales were associated with areas of higher chlorophyll-a concentration in the central and northern sections of the strait, which also corresponded to relatively higher temperatures and shallower mixed layer depths for the in situ data. In Bransfield Strait, humpback whales appeared to prefer the near-frontal zones and the deep basins, where surface waters are influenced by the Bransfield Current. Interannual variability in both humpback and minke whale encounter rates in Gerlache Strait was correlated with the Oceanic Niño Index, the oceanic component of ENSO. In addition to investigating species-habitat relationships with statistical models, I conducted the first study to describe the satellite-monitored movements of humpback whales on their feeding grounds along the Antarctic Peninsula. Results showed considerable individual variation in direction, speed and range of movements, and an overall pattern characterized by short- and long-distance movements between presumed foraging areas with relatively short residency times. All told, the results of my research show that humpback whale distribution within foraging habitat is influenced by physical and biological variables that enhance biological productivity.

abstract
Despite its essential role in bioenergetic modeling, reliable measures of energy expenditure (i.e., oxygen consumption) associated with the different activities of wild animals have remained elusive. Oxygen consumption rate (VOâ‚‚) associated with activity can be estimated as a function of heart rate (fh), and the empirical relationship between the two has been determined for several aquatic vertebrates while fasting and resting. However, the simplified fh:VOâ‚‚ relationships established from such studies may differ under more complex physiological circumstances, such as when animals are foraging at depth or feeding on prey. I assessed the efficacy of using fh to predict VOâ‚‚ in 7 captive Steller sea lions, Eumetopias jubatus, while fasting and feeding at rest (on land or in water) and while diving (up to 40 m in the open ocean). Linear mixed-effects models revealed that environment, amount of food fed, and type of diving activity all altered the fh:VOâ‚‚ relationship. They also showed that different linear equations are needed to predict VOâ‚‚ from fh for sea lions fasted while on land or in water, but that a single equation can predict VOâ‚‚ on land regardless of whether fasted or feeding. When in water, feeding animals a 4, 6, or 12 kg meal changed the fh:VOâ‚‚ relationship compared to fasted animals. While fh can reliably be used to predict VOâ‚‚ in diving sea lions, the relationship differed between single dive cycles (one dive +surface interval) and dive bout cycles (multiple dives+surface intervals). However, the equation that predicted VOâ‚‚ for single dive cycles did not differ from that for sea lions resting on the surface. Neither dive duration, dive depth, nor food consumed significantly affected the fh:VOâ‚‚ relationships. Heart rate could be used to predict VOâ‚‚ in diving sea lions, but only over complete dive cycles or dive bouts where animals recovered fully from the Oâ‚‚ debt incurred underwater. Based on these results, separate equations that distinguish among environmental, digestive, and diving states can be employed to accurately predict VOâ‚‚ from heart rate in wild Steller sea lions.

abstract
Morphometric measurements and daily feeding records of 62 captive Steller sea lions (Eumetopias jubatus) were analyzed to provide information about seasonal growth and food consumption that has been impossible to collect from wild animals. Data from nursing pups, intact and castrated males, pregnant, lactating and non-reproductive females were also used to determine differences in rates of maturity between males and females, and the effects that climate, sexual maturity, castration and pregnancy and lactation have on growth and food intake. Data were fit with seasonal (sine function) and annual (von Bertalanffy, logistic, Gompertz, Richard’s and maturity) growth models, and showed that males achieved larger body sizes than females by undergoing a growth spurt during puberty and by extending their growth throughout adulthood. Annual increases in the length and mass of females slowed significantly following sexual maturity. Males and females both experienced seasonal oscillations in body mass, but the seasonal fluctuation in male mass peaked later (April) and was far more dramatic than that of females. The mass of lactating and non-reproductive females peaked in early spring (March), while increases in the mass of pregnant females paralleled fetal growth, reaching a maximum before parturition. Changes in mass did not parallel changes in consumption. Fish intake by males and females peaked during winter and bottomed during late spring, while seasonal changes in body mass reached their high and low 3 to 4 months later than food intake. Pregnant and non-reproductive females differed little in the amount of prey they consumed, unlike lactating females that significantly increased their consumption during summer and winter. The differences between females highlight the relatively low additional energetic requirements of pregnancy and the high costs of lactation. Differences between neutered and intact males further suggest that testosterone affected overall male growth, but had smaller effects of seasonal oscillations in mass and did not affect food intake. The reproductive cycle and thermoregulatory requirements appeared to drive seasonal changes in body mass and food intake of male and female Steller sea lions but at different time scales. Our findings also indicate that mass is not a simple reflection of food intake, which has important implications for future nutritional research and bioenergetic modeling of wild pinnipeds.

abstract
Determining diets of pinnipeds by visually identifying prey remains recovered in faecal samples is challenging because of differences in digestion and passage rates of hard parts. Analyzing the soft matrix of fecal material using DNA-based techniques is an alternative means to identify prey species consumed, but published techniques are largely non-quantitative, which limits their applicability. I developed and validated a real-time PCR technique using species-specific mitochondrial DNA primers to quantify the diets of Steller sea lions (Eumetopias jubatus). I first demonstrated that the proportions of prey tissue DNA in mixtures of DNA isolated from four prey species could be estimated within a margin of ~12% of the percent in the mix. These prey species included herring Clupea palasii, eulachon Thaleichthyes pacificus, squid Loligo opalescens and rosethorn rockfish Sebastes helvomaculatus. I then applied real-time PCR to DNA extracted from faecal samples obtained from Steller sea lions that had been fed 11 different combinations of herring, eulachon, squid and Pacific ocean perch rockfish (Sebastes alutus), ranging from 7-75% contributions to a meal mix (by wet weight). The difference between the average percentage estimated by real-time PCR and the percentage of prey consumed was generally less than 12% for all diets fed when percentages of prey consumed were corrected for differences in mtDNA density among the prey items. My findings indicate that real-time PCR can detect the quantity of prey consumed for a variety of complex diets and prey species, including cephalopods and fish.

abstract
Reduced availability of high energy-content prey (nutritional stress) is a predominant hypothesis to explain the decline of Steller sea lion (Eumetopias jubatus) populations in western Alaska from the late 1970's to the late 1990's. Animals may respond to eating insufficient prey by increasing stress levels and decreasing metabolic rates. It may thus be possible to identify nutritional stress by measuring concentrations of GC metabolites (stress) and thyroid hormones (metabolism) shed in the feces of Steller sea lions. However, techniques to measure thyroid hormone concentrations from sea lion feces have not been developed. We quantified variation of triiodothyronine (T3) and thyroxine (T4) concentrations in Steller sea lion feces following two injections of thyrotropin (TSH) at 24 h intervals into four captive animals. Glucocorticoid (GC) metabolites were also assayed to examine any relationship to stimulated thyroid hormone secretion. We found that fecal T3 peaked 48 h post-injection and increased 25-57% in three sea lions (all animals, p=0.03). Pre-injection GC increases indicated stress from isolation for baseline fecal collections, but post-injection increases could not be confirmed as a response to TSH injections or as a product of the study design. The results demonstrated that pre- and post-injection changes in fecal GC and T3 concentrations were consistent with predictions of an increased stress response and metabolic rate within the animals. We then measured T3 and GC concentrations in 834 Steller sea lion fecal samples collected in 2005 and 2006 from 15 resting (haulout) and breeding (rookery) sites between British Columbia and the Central Aleutian Islands. Overall, GC concentrations did not differ between haulout populations (western 2006 pre-pupping and eastern 2005 post-pupping). Fecal hard-part analyses revealed a lower energy-content diet in the western population, suggesting that diet quality is a relevant hypothesis to explain slightly higher GC concentrations found in the western population, specifically the Aleutian Islands region. However, the nutritional stress hypothesis could not be substantiated through T3 concentrations. The rookeries possessed the highest energy-content diets, but also exhibited a nutritional stress response with a significantly higher GC and lower T3 concentration than either haulout population (possibly related to lactation or decreased leptin levels), but T3 comparisons performed at scales of site and region were inconclusive.

abstract
Developing appropriate management plans for species at risk requires information about their population structure and abundance. For most cetacean populations, few reliable population estimates are available and even fewer distributions have been mapped. Accurate abundance estimates can be determined from capture-recapture data if assumptions are met, however this can be difficult when the animal in question demonstrates both strong site fidelity and large-scale migrations, and different models can result in dramatically different results. I explored these issues by examining a 15-year dataset (1992-2006) of photo-identifications of humpback whales (Megaptera novaeangliae) in British Columbia (BC), Canada. I used multiple capture-recapture models to compare how the definition of population and variation in effort affected estimates of population size, and I explored means to correct for these biases. I also considered stock structure by examining individual breeding ground destinations, movement, and localized site-fidelity within BC. Across the six models considered, the BC humpback whale abundance in 2006 ranged between 1,428 and 3,856 individuals. The Lincoln-Petersen estimate (1,428-1,892) likely best described the number of humpback whales in BC during summer 2006. The effort-standardized Jolly-Seber model (1,970-2,331) is more representative of the larger population of humpback whales that uses or passes through BC over multiple years. Ultimately, selecting the best estimation model requires defining the ‘population’ of interest and accounting for spatial and temporal distribution of sampling effort. British Columbia provides feeding habitat and a potential migratory corridor for whales that breed in the northeastern Pacific Ocean. Forty-four percent of the 1,986 humpback whales considered were sighted in BC in more than one year. Identifications were highest from May to October, with a peak in September, but humpback whales were present in BC in all months of the year. Whales showed strong site fidelity with a median re-sighting distance of 75 km between years, and a maximum re-sighting distance that ranged from 0.41 km to 842 km. Matching rate within BC decreased as a function of north-south distance, though no clear north-south boundary could be established. Stock structure of humpback whales in British Columbia is complex and should be considered in managing this population.

abstract
The ability of animals to contend with unpredictable seasonal shifts in quality and quantity of prey has implications for the conservation of wildlife. Steller sea lions (Eumetopias jubatus) were subjected to different quantities and qualities of food to determine what physiological and endocrine responses would occur and whether they differed between season (summer and winter) or diet (high-lipid Pacific herring Clupea pallasi vs. low-lipid walleye pollock Theragra chalcogramma). Eight females were divided among two groups. One (Group H) were fed herring for 28 days (baseline), then received a reduced caloric intake for a subsequent 28 days (restriction) to induce a 15% loss of body mass. The second (Group P) were also fed herring during the baseline followed by a reduced isocaloric diet of pollock during the restriction. Both groups subsequently returned to their baseline intake of herring for a 28-day controlled re-feeding. The two groups of sea lions lost identical mass during restrictions independent of species eaten, but did differ in the type of internal energy reserve (protein vs. lipids) they predominantly used. Group H lost significantly more lipids and less lean mass than Group P in both seasons. In summer, Group H also increased activity levels and decreased thermoregulation capacity to optimize energy allocation. No such changes were observed for Group P whose capacity to adjust to the reduced caloric intake seemed to have been blocked by the pollock diet. During winter, the sea lions spared energy allocated to activity (especially Group H) and preserved thermoregulation capacity. Changes in body mass was negatively related to free cortisol and positively related to IGF-1 in winter, but only IGF-1 was related to changes in mass in summer when lean mass regulation seemed more important. Levels of IGF-1 were associated with changes in protein metabolism in both seasons for both groups, but changes in body condition were never explained by the measured metabolites or hormones. The cap! acity to compensate for mass loss was seasonally dependent with sea lions displaying compensatory growth (by restoring lipid stores) in winter but not in summer. Summer appears to be a more difficult season for sea lions to recover from mild nutritional stress. These physiological findings can be used to refine bioenergetic models needed for the conservation of Steller sea lion populations.

abstract
Variability in length of lactation and maternal association allows otariids flexibility to buffer their young against changes in nutrition. It also increases the chance of their young surviving to sexual maturity, which is particularly important in a declining species such as Steller sea lions (Eumetopias jubatus). Timing of weaning is a critically important event in mammalian development that can affect subsequent aspects of an animal‘s adult life, and may hold the key to understanding the population dynamics of Steller sea lions. Unfortunately no studies have yet fully documented the behavioural ecology of Steller sea lions outside of the breeding season. The goal of my study was to document suckling behaviour over 13 consecutive months to determine the timing of weaning for male and female Steller sea lions under three years of age at Southwest Brothers Island, Southeast Alaska (July 2004 – July 2005). I also wanted to ascertain the haulout patterns and activity levels of the colony in relation to season, prey availability, time of day, and weather. Finally, I sought to evaluate the feasibility of using an automated, time-lapse camera system to monitor sea lions and its potential for future use. Male Steller sea lions were found to suckle longer than females, with a greater proportion of males than females suckling at one year. Time spent suckling declined with age suggesting that the animals became more independent as they grew older, most likely as they increased their ability to forage successfully on their own. Male sea lions that remained with their mother for longer than one year may have had reduced exposure to predation, and obtained more calories with less energy expenditure from milk, compared to females that became nutritionally independent sooner. As a result, this may provide males with a chance to grow as big as possible, as fast as possible, and increase their ability to hold a territory and have access to mates later in life. The number of sea lions onshore at Southwest Brothers Island was influenced by weather on a daily time-scale, but also displayed seasonal changes that may have been related to prey availability and the timing of breeding. The colony abandoned the island mid-March to mid-April, coinciding with the herring spawn and eulachon runs, which are high-fat species and spatio-temporally predictable prey. High daily variability in numbers of animals at Southwest Brothers likely reflected movement of animals to and from other nearby haulouts. Activity levels varied throughout the year, with proportionally more animals resting in the summer and more animals engaged in low activities in the winter. This suggests a higher behavioural expenditure of energy in the winter, contributing to their need for high quality nutrition. June and July is an optimum time to assess sea lion numbers due to the high number of animals onshore at that time and a greater predictability in sea lion behaviour. The counts obtained from the automated time-lapse camera system‘s digital images correlated with counts obtained from direct observation (r2 = 0.99). The direct counts were on average 22% greater than the digital images. While direct observation is the best method for obtaining a greater variety of data, the camera systems have a good potential to be used to monitor Steller sea lions and other species when researchers cannot be physically present.

abstract
Steller sea lions range across the Pacific rim from Southern California in the east to northern Japan in the west, where they have continuously occupied terrestrial resting sites (haulouts) and breeding sites (rookeries) for hundreds of years, if not longer. Why they choose (and stay) at these locations, and what their preferred habitat is, remains unknown. Thus, two aspects of the Steller sea lion?s habitat usage were examined?the oceanographic and the terrestrial. For the oceanographic aspect, spatial models were constructed to determine which oceanographic factors are associated with haulouts and rookeries, and how conditions near sites might differ from conditions elsewhere. The two modelling techniques employed (logistic regression and supervised classification) were evaluated using the kappa statistic (Kno), and receiver-operating characteristic(ROC) plots. Supervised classification was found to produce better-fitting models than logistic regression. In general, Steller sea lions showed preferences for sites associated with waters that were relatively shallow, well-mixed, had higher average tidal speeds and less-steep bottom slopes. Conditions within 1 nautical mile of land were better predictors of haulout and rookery locations than were conditions within 10, 20, and 50 nautical miles. No consistent differences were found in the physical characteristics of waters surrounding sites in the eastern and western populations of Steller sea lions, or between haulouts and rookeries. Regarding the terrestrial aspect of their habitat, anecdotal accounts describe Steller sea lions as predominantly occupying exposed, rocky shorelines, but this habitat preference has never been quantified. Locations of haulouts and rookeries were compared against a coastline type database to identify the shoreline preferences of Steller sea lions and to look for other spatial trends in site characteristics. Haulouts and rookeries were preferentially located on exposed rocky shorelines and wave-cut platforms. No relationship was found between either latitude or longitude of a site and its average non-pup count. The results indicate that there are differences in both the oceanographic and terrestrial characteristics of sites used by Steller sea lions versus areas of coastline where they are not found. The models could be used to predict changes in habitat use given changing physical conditions, and could be applied to any central-place forager.

abstract
Otariids such as the Steller sea lion (Eumetopias jubatus) are among the most manoeuvrable of marine mammals (expressed as a minimum turning radius and speed during manoeuvres). They evolved in terrestrial and aquatic environments that are structurally complex, and feed on prey that are an order of magnitude smaller than themselves. Compared to other aquatic organisms, Steller sea lions have an unstable body design and are presumed to invoke swimming techniques that reflect their need to be highly manoeuvrable. Detailed information was experimentally obtained about the turning techniques employed by otariids through jointly analysing kinematic and kinetic parameters measured from video recordings of three captive Steller sea lions. Centripetal force and thrust production were determined by examining body movements throughout a series of turns. Results showed that most of the thrust was produced during the power phase of the stroke cycle of the pectoral flippers. As ! opposed to previous findings, very little or no thrust was generated during initial abduction of the pectoral flippers and during the final drag-based paddling style of the stroke cycle. Peak of the thrust force was reached halfway through the power phase, while the centripetal force reached its maximum value at the beginning of the power phase. Kinematic aspects of the manoeuvres changed with the tightness of the turns and the initial velocities. The degree of dorsal flexion of the body changed with the turning radius and the degree of flipper abduction varied with swimming speed. However, the general manoeuvring technique and turning sequence remained the same in all the recorded manoeuvres. Contrasting the turning performance of the Steller sea lion with a simple dynamic model of unpowered manoeuvres in aquatic animals showed significant departures from model predictions due to the hydrodynamic effects of body movements. Overall, the turning sequence of the Steller sea lion was found to be very consistent, and their manoeuvrability was found to come from their ability to vary the duration and intensity of movements within the turning sequence.

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Marine ecosystem management has prompted the need for better understanding of the impact of marine mammals in the oceans. Using the wealth of information available in the literature, a rule based multiple regression model was developed to estimate the energy requirements of all 124 marine mammal species. This meta-analysis modeling framework provided a simple means for estimating the energetics (metabolism or consumption) of marine mammals under varying conditions, as a function of easily obtained or estimated physiological and environmental variables, including morphology, developmental stage, growth, sex, reproductive status, health, activity, postabsorptive state, thermoneutral condition, and season. Based on different combinations of input variables, a set of empirical equations was developed. The empirical equations provide an objective predictive tool for estimating the energy requirements of data deficient marine mammal species. Extensive model validation indicated that all models were robust to their statistical assumptions, including phylogenetic independence, and captured a substantial amount of the observed heterogeneity in energy requirements (up to 82% residual variance). Equations also synthesize evidence of a uniform pattern of energy use, from consumption to expenditure, and provide quantitative rough estimates of the components of the bioenergetic framework for all marine mammal species. Results suggest that body mass is a better predictor of energy requirements than body length, although length may be used in circumstances when mass cannot be estimated or measured. Of the parameters considered, model predictions were most sensitive to uncertainty in morphology, developmental stage, activity, and growth. By including flexibility in prediction and uncertainty in estimates, results extend the simple allometric scaling relationships with mass alone (e.g., Kleiber’s Equation), and refine estimates of marine mammal energy requirements currently available. Results serve as a useful starting point from which complex analyses can proceed, and provide a basis against which other models can be compared. The method provides an objective means for researchers and resource managers to select an equation most appropriate for their predictive needs, even for data-deficient species, given different levels of available input information. The empirical models are useful tools for parameterizing ecosystem models and can be used to help address ecological questions and issues pertaining to conservation and resource management.

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There is considerable interest in assessing and mitigating disruptive effects of humans on the behaviour of marine mammals, especially for species with uncertain or decreasing population trends. Steller sea lions (Eumetopias jubatus) have been under intensive study throughout their range over the past few decades in an attempt to identify the causes of a large population decline in the Gulf of Alaska and Aleutian Islands. Consequently, disturbance due to scientific research has also increased at rookeries and haulouts. The purpose of my study was to determine if there were measurable short-term effects of human disturbance on the numbers of Steller sea lions using terrestrial sites. Numbers and composition of sea lions were documented for 2 – 3 week periods in southeast Alaska and British Columbia during summer (n = 8 sites) and winter / spring (n = 6 sites). They revealed considerable daily variation in numbers of sea lions hauled out within and among study sites that was related in part to prevailing environmental conditions. However, counts could not be corrected to account for environmental influences on the total numbers of sea lions using haulouts. Hauling out trends were examined for pre- and post-disturbance periods across multiple sites over two seasons. Predetermined research disturbances occurred to collect scats at the haulouts, and to brand pups at the rookery. Three methods were explored to assess local population recovery that addressed both quantitative and temporal aspects of sea lions returning to the study locations. Disturbances resulted in significantly fewer sea lions using haulouts during the post-disturbance period. Variation in the numbers of animals using the haulouts increased following the disturbance, but rates of change in daily numbers did not differ significantly between periods. Six of ten disturbed sites reached full recovery (100% of the pre-disturbance mean) on average 4.3 days after the research disturbance. To determine if individual behaviour was affected by disturbance, sea lions arriving on shore were followed to determine normal patterns of interactions and behaviour. Significant differences were noted in hauling out behaviour between animals that remained on land and those that returned to the water. Sea lions that returned to the water exhibited higher rates of behaviour and interactions with other animals during the week that followed the disturbance. Seasonal differences were also noted in the rates of behaviour and interactions that may be indicative of certain times of the year when sea lions are more sensitive to human presence and disturbance. Increasing levels of human–sea lion contact are expected as more and more people visit the remote coastal habitat of Steller sea lions. Future studies are needed to assess the influence of disturbance on sea lion redistribution within a critical recovery period, as well as to determine the physiological effects that sea lions experience with repeated human disturbance. Disturbance studies are an important aspect of conservation initiatives because they can help guide policies and establish restrictions to protect wild populations from human intrusion.

abstract
The killer whale (Orcinus orca) is one of the few species for which vocal culture is actively involved in the development and maintenance of the social organizations of populations. In particular, the social structure of one form of killer whales, called residents, is a good example of this involvement. Resident societies are characterized by associations of groups with highly stable membership, which allow an in-depth examination of the association between vocal culture and the nested social hierarchy of that population. Resident killer whales live in small populations where inbreeding is a threat to their genetic diversity. Genetic and cultural evolution may be closely linked in killer whales, as has been proposed for a number of other cetaceans with matrilineal social structure. To test for a possible link between genetic and cultural evolution in killer whales, I investigated vocal similarities and differences among mixing and non-mixing resident groups and between two ecotypes, residents and transients. First, I examined whether clans exist among resident killer whales in Southern Alaska. Vocal clans had been previously identified in British Columbia but not in Alaska. Two acoustically distinct clans were recognized, each of which was monomorphic for a different mitochondrial D- loop haplotype based on results of a separate genetic study. Thus, acoustic similarities within these cultural groups reflect common matrilineal ancestry, which suggests that clan-based social structure is a fixed characteristic of resident killer whales. Second, I examined the similarity of vocal repertoires between residents and transients, and among clans and communities within residents. Call type similarity does not exist above the clan level. To investigate vocal similarity above the clan level, I split calls into syllables, and compared their distribution among population levels. Structural variation of upper frequency syllables characterized vocal variation among clans of the same community, while usage of distinct lower frequency syllables reflected divisions among communities and between residents and transients. Third, I examined syntax, the ordered arrangement of syllables, among clans of resident communities. I found that vertical transmission of syllable order in matrilines is important for the distinctiveness of call type repertoires and leads to clan-specific syntax rules. Previous work has shown that mating mainly takes place between clans. Because syntax similarity appears to be negatively correlated with sociality among clans, resident killer whales may use syntax variation to choose mates with low levels of genetic relatedness. The link between vocal culture and social structure likely influences mate choice in resident killer whales. This link leads to gene-culture co-evolution in killer whales and makes them excellent candidates for studies of cultural taxonomy.

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The comprehensive changes that have occurred in the Bering Sea over the last 30 years have prompted a wide range of studies to better understand the ecosystem as a whole. One set of studies has used the Ecopath with Ecosim (EwE) modelling software to synthesise existing biological data and gain insight into how the ecosystem was before and after the system-wide changes. This modelling framework provides a means for tracing contaminants through the ecosystem, and evaluating the role that persistent organic pollutants (POPs) may have played in the changing dynamics of the eastern Bering Sea. Using the EwE software, the likely pathways of PCB flow within the eastern Bering Sea were identified and health implications of contaminant exposure for Steller sea lions, other species of marine mammals, and humans were evaluated. The base EwE model was refined from existing models and validated with traditional stock assessment data. Ecotracer (a component of the EwE software) tracked th e bioaccumulation of contaminants moving through the system with biomass. The models estimated contaminant concentrations for species and functional groups that have not previously been measured. Results suggest that PCB concentrations for most species in the eastern Bering Sea have remained below threshold levels associated with negative reproduction and survival effects. However, these concentrations may have subtle effects on adults and more serious effects on foetuses and nursing young, which could inhibit the recovery of Steller sea lions and other species that have declined in the eastern Bering Sea. Although the benefits of traditional foods appear to continue to outweigh the risks posed by contaminants for humans, PCB exposure and dietary intake for many Alaska Natives subsisting on marine mammals is above the USEPA Daily Reference Dose. Results extend the existing eastern Bering Sea models and are important in terms of management alternatives for marine mammals and human health. They also synthesise evidence regarding the pr! esence, extent, and movement of PCBs throughout the system. The refined eastern Bering Sea models are useful tools for exploring different scenarios and hypotheses, to inform resource managers, and to further our understanding of this ecosystem.

abstract
Harbour porpoise (Phocoena phocoena) occur year round in the waters of southern British Columbia, but little is known about their seasonal abundance, habitat use and food habits. A systematic vessel-based line transect survey was undertaken to quantitatively assess seasonal trends in harbour porpoise abundance and distribution within the Canadian waters of Juan de Fuca and Haro Straits (08 September 2001 to 31 August 2002). These data were supplemented with opportunistic counts (1995-1996, 1998-2001) and stomach contents from post-mortem stranded porpoise (1998-2001). The study area encompassed 805.3 km 2 ; with a total transect length of 1838.4 km. Data collection was restricted to Beaufort 0 and 1 sea conditions, and abundance was estimated using DISTANCE 3.5 software. Encounter rates observed from April to October were significantly higher than from the rest of the year. Seasonal abundance estimates (corrected for visual radial distance estimation) ranged from a high of 673 porpoise from April-October (CV=20.5%, 95% CI 450 - 1006) and declined to 208 porpoise from November-March (CV=37.5%, 95% CI 101 - 429). Harbour porpoise were not uniformly distributed within the study area. Localized areas of high counts may represent critical porpoise habitats. A bimodal distribution of stranding frequency corresponded to the period of increased abundance. Ten adult and five immature harbour porpoise stomachs were examined (8 males and 7 females). Fish bones and otoliths were identified to species. Each stomach contained only a single species of piscine prey (n=5). No cephalopod beaks or eye lenses were present. Specimens from south Vancouver Island contained sand lance (Ammodytes hexapterus), with the one from the southeast coast containing Pacific hake (Merluccius productus), and the one from the southwest coast containing Pacific herring (Clupea pallasi).

abstract
Potential competition for food resources between marine mammals and fisheries has been an issue of much debate in recent years. Given the almost cosmopolitan distributions of many marine mammal species, investigations conducted at small geographic scales may, however, result in a distorted perception of the extent of the problem. Unfortunately, the complexity of marine food webs and the lack of reliable data about marine mammal diets, abundances, food intake rates etc., currently preclude the assessment of competition at adequately large scales. In contrast, the investigation of global resource overlap between marine mammals and fisheries (i.e., the extent to which both players exploit the same type of food resources in the same areas) may, however, be easier to achieve and provide some useful insights in this context. Information about the occurrence of species is a crucial pre-requisite to assess resource overlap and also to address other marine mammal conservation issues. However, the delineation of ranges of marine mammals is challenging, due to the vastness of the ocean environment and the difficulties associated with surveying most species. Consequently, existing maps of large-scale distributions are mostly limited to subjective outlines of maximum range extents, with little additional information about heterogeneous patterns of occurrence within these ranges. I developed a new, more objective approach to map global geographic ranges and the relative environmental suitability (RES) for 115 marine mammal species. This habitat suitability model is a rule- based environmental envelope model that can utilize not only quantitative data, but also alternative, non-quantitative and more readily available information about species habitat preferences (such as expert knowledge). As a first step, I assigned each species to broad-scale ecological niche categories with respect to depth, sea surface temperature and ice edge association based on synopses of published qualitative and quantitative habitat preference information. Within a global grid with 0.5 degree latitude by 0.5 degree longitude cell dimensions, I then generated an index of the relative environmental suitability (RES) of each cell for a given species by relating quantified habitat preferences to locally averaged environmental conditions in a GIS modeling framework. RES predictions closely matched published distributions for most species, suggesting that this rule-based approach for delineating range extents represents a useful, less subjective alternative to existing sketched distributional outlines. In addition, raster-based predictions provided information about heterogeneous patterns of the relative suitability of the environment and potential core habitat for each species throughout its range. I validated RES model outputs for four species (northern fur seals, harbor porpoises, sperm whales and Antarctic minke whales) from a broad taxonomic and geographic range using ‚at-sea™ sightings from dedicated surveys. Observed relative encounter rates and species-specific predicted environmental suitability were significantly and positively correlated for all species. In comparison, observed encounter rates were positively correlated with < 3 % of 1000 simulated random data sets of species occurrence. To validate the RES predictions for data-deficient species such as beaked whales (Ziphiidae, Cetacea), I developed a different evaluation approach using stranding records as an alternative type of test data. Ziphiids represent one of the least known families of mammals, primarily known from strandings, along with only a few known ‘at-sea’ records for each species. Using a global data set of residual ocean currents, I developed a simulation model of ziphiid strandings and used this to generate relative probabilities of strandings along all coastlines. Predictions were generated based on two different input distributions: species-specific RES predictions and uniform distributions based on published information, which served as the null model. Large-scale patterns of simulated strandings based on RES predictions produced significant correlations with observed strandings for five times as many species (10 of 21 ziphiid species) as those generated based on the null model (2/21), suggesting that RES predictions represent an improvement over existing simple outlines. The extensive validation provided support that RES predictions capture patterns of species occurrence sufficiently enough to be used as the basis for large-scale investigations of marine mammal-fisheries interactions. I therefore used the model to assess the importance of spatial aspects for the investigation of overlap between marine mammals and fisheries in terms of food resource exploitation. To assess spatially-explicit resource overlap, I first estimated global annual food intake (specified by food types) for each species based on a basic food consumption model. This model required information about global population abundances, sex-specific mean weights, standardized diet compositions, and weight-specific feeding rates, which was obtained through the compilation, screening and processing of more than 2000 publications. By linking species-specific RES predictions with estimated consumption for each species, I generated spatially-explicit food consumption rates (expressed as food intake per km2 per year). Superimposing geographically disaggregated fisheries catches (generated by a similar model) allowed me to calculate overlap between catches and consumption with respect to both the composition of food types and areas where food / catches were taken. The model indicated that, in the 1990s, average consumption by all marine mammal species combined was several times higher than total fisheries catches during the same time period. However, effective spatial overlap and exploitation of the same food types was relatively low, suggesting that actual competition between fisheries and marine mammals may be much lower than proposed. I predicted the highest resource overlap in the temperate to subpolar shelf regions of both hemispheres, though overlap is more pronounced in the North. Overall, < 15 % of all fisheries catches and < 1% of all estimated marine mammal food consumption stem from areas of high predicted overlap. Nevertheless, overlap between marine mammals and fisheries may be an issue of concern on smaller scales (especially for species with small feeding distributions) that requires more detailed, local investigations. I propose that mapping of suitable habitat for marine mammals using the new RES model is useful for evaluating current assumptions and knowledge about species™ occurrences, especially for data-poor species. Generated hypotheses about suitable habitat and species™ occurrences may help to focus research efforts on smaller geographic scales, and usefully supplement other, statistical habitat suitability models. Furthermore, the mapping of food consumption rates and geographical 'hotspots' of marine mammal-fisheries interactions will help to identify potential areas of highest conflict and may aid the development of management approaches at appropriate scales.

abstract

Steller sea lions (Eumetopias jubatus) were fed restricted iso-caloric amounts of Pacific herring (Clupea pallasi) or walleye pollock (Theragra chalcogramma) for 8-9 days, four times a year. At these levels, the sea lions lost an average of 10.1% of their initial body mass while on both experimental diets for up to nine days, but at a significantly higher rate in winter and at a lower rate in summer. Decreases in body fat mass and standard metabolic rates during the trials were similar throughout the seasons and for both diets. Metabolic depression was not always observed during the trials despite the constant loss of body mass. Changes in cortisol, triiodothyronine and blood urea nitrogen (BUN) were seasonally dependent. Over the course of the trials, serum levels of cortisol and BUN increased and total triiodothyronine decreased the most in winter. Serum cortisol levels correlated negatively with both body mass and body condition suggesting that cortisol may play an important role in body fat regulation in Steller sea lions. The mean ghrelin level in Steller sea lions correlated negatively with body mass, but ghrelin did not correlate with serum leptin. My findings support the hypothesis that restricted energy intake at different times of the year differentially affects Steller sea lions, and that diet type (herring or pollock) may have seasonally-specific effects on body mass and composition. Steller sea lions may be more severely impacted by reduced energy intake in winter than at other times of the year.

Changes in iron binding capacity were significantly greater in the herring-fed group than in the pollock-fed group, and a significantly greater decrease occurred in winter and spring compared to summer and fall. Iron saturation increased in the herring-fed group and decreased in the group fed pollock. These results suggested a potential anemia from a reduced diet of pollock in Steller sea lions. Serum iron, phosphorus, hematocrit and gamma glutamyltransferase showed consistent changes during food restriction, suggesting that these may serve as indicators of nutritional stress in Steller sea lions.

abstract
The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has a mandate to manage Southern Ocean resources using an ecosystem approach. In accordance with this, ecosystem models of the South Orkneys/South Georgia region (FAO Subareas 48.2 and 48.3, respectively) were constructed using the modelling software Ecopath with Ecosim. A model representing the region in the 1990s was used to assess the possible effects that an increased fishery for krill (Euphausia superba) might have on the ecosystem. The model predicted that the expanded fishery could cause small declines in the biomass of several top predators (<10%), such as Antarctic fur seals and baleen whales, and that bycatch in the krill trawl fishery could reduce some fish populations by almost 35%. Incorporating the natural annual variation in krill biomass into the model showed that predator populations could be negatively affected by years of low krill abundance, which would be further exacerbated by an increased krill fishery. The model also indicated that the traditional concept of the simple Southern Ocean food chain (i.e., primary production, krill, top predator) should be re-evaluated to consider other important intermediary species groups, such as fish and squid. Models representing the region in the past (pre-exploitation, 1900s and 1960s) were used to assess the impacts of commercial sealing, whaling and fishing in the region. Simulations suggest that the increase in Antarctic fur seals since the 1950s was not due to decreased competition for food as a result of the whaling activities in the first half of the 1900s. However, whaling may have had a positive effect on fish population sizes, especially certain commercially important species. Removing large krill predators from the simulated ecosystem, such as birds and seals, did not result in an increase in whales. Removing certain fish groups, however, had more of an acceleratory effect on whale recovery. These findings emphasize the need for a better understanding of the relative roles of species in the Southern Ocean ecosystem, as well as the natural variability of krill abundance, if management issues in the Antarctic are to be resolved.

abstract
I documented the timing and progression of the moult by sex and age class in a wild population of Steller sea lions (Eumetopias jubatus) on Lowrie Island, Alaska (Jul-Nov 2001) and from captive animals at the Vancouver Aquarium Marine Science Centre (1993-2000). In the wild, juveniles (ages 1-2 years) were the first to moult followed by adult females, bulls and pups. The mean date when juveniles started their moult was 21 Jun which was significantly different from the mean start date of 07 Aug for adult females, and differed from the mean start date for pups of 01 Sep (one month later). Mean completion dates were also about one month apart (19 Sept for juveniles, 26 Oct for adult females and 17 Nov for pups). Duration of the moult was about 45 days for each age group (pups and adult females). However, duration of the moult for captive sea lions was longer (averaging 83.5 days) and differed among years and within age classes. Patterns of hair loss in the wild (i.e., the progression of the moult over the body surface) differed among (i) pups, (ii) juveniles and early moulting adult females, and (iii) bulls and later moulting adult females. Differences in the timing and progression of the moult may be related to physiological changes and interactions of hormones associated with body condition and the reproductive cycle.

abstract
Steller sea lions (Eumetopias jubatus) in the Gulf of Alaska declined since the late 1970s. Their population decline might be related to a shift in their diet fiom fatty, high-calorie fishes such as herring (Elupea palhi) to low energy density fish such as walleye pollock (Theragma chalcogrumma). I compared the nutritional value of herring with pollock and explored seasonal changes in the nutrient content of pollock. I also compared the nutritional status of three captive Steller sea lions fed pollock and herring. Hemng was a more concentrated in dietary lipid (p<0.001) and energy source (p<0.001) than pollock. The protein of herring was also higher in digestibility (p=0.015) than pollock protein, which could indicate that even if ingested energy was equal in both diets, absorbed energy for body knctions may be reduced when pollock is eaten. There was little difference in the protein quality of pollock and herring with the exception that valine was more abundant in herring (p=0.004). The energy content,of pollock changed seasonally, with the peak in energy concentration occurring in the summer and fall (July to November) and then declining over the winter prior to spawning. Captive Steller sea lions lost mass or increased mass at a slower rate on a pollock diet than when they consumed hemng, at which time, they all increased in mass. The sea lions had lower levels of plasma cholesterol when fed pollock. Their red blood cells were also more susceptible to oxidation, which corresponded with lower plasma vitamin E levels. These findings suggest that consumption of predominantly pollock has nutritional consequences for the Steller sea lion. Even if they are able to increase their caloric intake to maintain their body mass, Steller sea lions may still be more susceptible to disease originating from oxidative stress.

abstract
The Strait of Georgia is a highly productive region and among the most important marine systems in British Columbia. It is at the mouth of the Fraser River, one of the most productive river systems in North America. Marine mammals are apex predators in this system, with at least ten species using the area during all or part of the year. Line transect surveys aboard B.C. Ferries vessels were conducted from May 1, 2000 to April 30, 2001 to determine the distribution and abundance of marine mammal species in the Strait of Georgia. A total of 2,879 individuals, representing nine species, were seen in 898 sightings. Harbour seals (n = 1,629), California sea lions (n = 415), Dall’s porpoise (n = 397) and Steller sea lions (n = 205) were the most frequently observed, accounting for 92% of the sightings. Pacific white-sided dolphins (n = 110), harbour porpoise (n = 71), killer whales (n = 49), gray whales (n = 2), and a minke whale were also seen during the surveys. Abundance estimates were highest in spring and lowest in winter, with a second smaller peak in abundance in autumn. Pinnipeds were estimated to consume the most prey due to high population estimates for harbour seals and large body size of adult male sea lions. Peaks in marine mammal abundances appear to coincide with seasonal physical and biological factors in the Strait of Georgia and Fraser River system that may influence the availability of prey species.

abstract
The decline of Steller sea lions (Eumetopias jubatus) in the Gulf of Alaska appears to have been associated with a switch of diet fiom one dominated by fatty forage fishes (such as herring - Clupea pallasi) to one dominated by low fat fish (such as pollock – Theragra chalcogramma). Observations made during the decline include reduced body size of sea lions, low pregnancy rates, poor fur quality and high mortality. I used the general mammalian model, Rattus nowegicus, to test whether changes in size and reproductive performance could be caused by a switch in the quality of prey consumed. I fed five groups of 12 female, weanling rats diets composed of herring (H), pollock (P), pollock supplemented with herring oil (PH), pollock supplemented with pollock oil (PP), or a semi-purified diet (ICN). Mean body weights were greatest for H, followed by PH, P, PP and finally ICN, although ICN was the only group significantly different from the others. Food intakes prior to mating were 10% higher for groups on the lower fat diets (P and ICN), resulting in similar caloric intakes in all groups. Efficiency of energy utilization was also similar for all fish diets. However, this efficiency was slightly reduced when pollock was supplemented with oil (PP and PH) compared to pollock alone. The protein efficiency ratio (PER) was highest for the H diet, slightly lower for all pollock diets, and significantly lower for ICN. Rats fed the low energy P and ICN meals did not compensate by consuming more during gestation. The fetal weights for mothers fed pollock (P) were significantly reduced. This study shows that the caloric content was a major limiting factor in the nutritional quality of pollock. If food intake was adjusted to meet energetic requirements, there were no detrimental consequences to eating pollock. However, supplementation of pollock meal with additional pollock oil may reduce growth and reproductive performance, although the reasons for this were not apparent.

abstract
The potential use of heart rate to monitor energy expenditure in free-ranging Steller sea lions (Eumetopias jubatus) was investigated by establishing whether a relationship exists between heart rate (fH) and oxygen consumption ( ) in captive sea lions while swimming and resting. Four trained Steller sea lions (2 males and 2 females; mass 87.4 -194.4 kg; ages 16 months–3 years) were equipped with a datalogger and two dorsal electrodes to record ECG (from which fH was calculated). Four styles of electrodes were developed and tested before selecting a final subcutaneous design. (measured with open-circuit respirometry) was simultaneously recorded while the previously-fasted animal was at rest within an enclosed dry metabolic chamber or while it swam in an enclosed swim mill against water currents of various speeds (0-1.5 m.s-1). The mean regression equation describing the relationship between fH (beats.min-1) and (ml.min-1.kg-0.73) for all four animals was = (0.68fH ± 0.07 s.e.) – (15.07 ± 6.20) (r2=0.72, p<0.01). The possibility that the fH/ relationship could be affected by digestion was investigated by feeding one of the male Steller sea lions either 6 or 12 kg of herring prior to entering the swim mill. increased over time after ingestion, while heart rate usually remained stable or decreased. The resulting relationship, = (0.24fH ± 0.03) – (18.49 ± 02.68) (r2=0.19, p<0.01), differed significantly from the relationship derived while the animal was fasted, indicating that digestion may alter the relationship between fH and . Fasting and feeding intervals must therefore be taken into account when considering the use of fH/ relationships to estimate energy expenditure from heart rate of free-ranging sea lions. The relationship demonstrated between fH and while fasting suggests that heart rate can potentially be used to monitor energy consumption in free-ranging Steller sea lions. However, additional research should be conducted to further elucidate how the relationship is affected by such factors as digestion, sex, stress, and development.

abstract
Analysis of data recorded from 24,862 whales killed by British Columbia coastal whaling stations between 1908 and 1967 revealed trends in the abundance, sex ratios, age structure and the distance from shore of sperm (Physeter macrocephalus), sei (Balaenoptera borealis), fin (Balaenoptera physalus), humpback (Megaptera novaeangliae) and blue (Balaenoptera musculus) whales. Trends in the relationships between records of where the whales were killed (n=10,275) and a simple oceanographic mode l were used to build generalized linear models, from which predictions of whale habitat were generated. The catch data were analyzed using annual and monthly mean values. Monthly and annual variation in whaling effort was deduced from accounts of the history of British Columbia coastal whaling, and biases arising from changes in effort were considered in the interpretation of the results. Predictive habitat models were produced at annual and monthly time scales based on an initial analysis of the univariate relationships between whale presence-absence and six independent predictor variables (depth, slope, depth class, sea surface temperature and salinity, and month). During the later years of whaling (1948 to 1967), the mean lengths of captured whales declined significantly in all five species and pregnancy rates dropped to near zero in fin, sei and blue whales. Monthly patterns in numbers killed revealed a summer migration of sei and blue whales past Vancouver Island, and confirms anecdotal suggestions that local populations of fin and humpback whales once spent extended periods in the coastal waters of British Columbia. Furthermore, the data strongly suggest that sperm whales mated (April-May) and calved (July-August) in British Columbia’s offshore waters. The habitat models showed that the continental slope and a large area off the northwest coast Vancouver Island may represent critical habitat for sei, fin and male sperm whales. Female sperm whales, blue and humpback whales appeared less sensitive to the predictor variables, however, the sample size for these groups was significantly smaller than for the other species. The habitat predictions lend support to the hypotheses regarding sperm whale breeding and predict humpback whale habitat in sheltered bays and straits throughout coastal British Columbia. The habitat models also generated hypotheses about the relationships and processes that link these whale species to their environment. The historic whaling records reveal much about the migratory behaviour and distribution of the large whales species as they once were, and may continue to be, in the Northeast Pacific. Verifying the persistence of these trends in the remnant populations is a necessary and logical next step.

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The primary goal of my study was to develop a bioenergetic model to predict the food requirements of Steller sea lions (Eumetopias jubatus). An important component of the bioenergetic model was a physical growth model. Growth models were constructed using morphometric measurements of males (≥ 1 year old), females (≥ 1 year old), and pregnant females with a foetus that had been shot on rookeries, haulouts, and in the coastal waters of southeastern Alaska, the Gulf of Alaska and along the Bering Sea ice edge between 1976 and 1989. A Richards model best described age related growth in body length and mass. Males grew (in length) over a longer period than females and exhibited a growth spurt in mass which coincided with sexual maturity. Sexual dimorphism in both body length and mass was significant by 3 years of age. The average predicted standard lengths of males and females older than 12 years were 3.04 m and 2.32 m respectively, while the average predicted weights were 681 kg and 273 kg respectively. Residuals of the size at age models indicated seasonal changes in growth rates. Young animals (<6 years old) and adult males grew little during the breeding season (May - July), and adult males did not resume growth until sometime after November. The bioenergetic model was used to estimate the food requirements of the Alaskan Steller sea lion population in the 1990’s and to examine how these food requirements varied seasonally and spatially. Input included age/sex-specific energy requirements, population size/composition, and diet composition/energy content by date and region of Alaska. Error in model predictions was calculated using uncertainty in parameter values and Monte Carlo simulation methods. Food requirements were generally lowest in the summer and highest in the winter and spring mainly due to changes in activity budgets and the energy content of the diet. The mean daily food requirement of pregnant females was only marginally greater than the mean daily food requirement of non-pregnant females of the same age, but the mean daily food requirement of females nursing pups was about 70% greater than females of the same age without pups. Per capita population food requirements differed by up to 12% among regions of Alaska due to differences in the energy content of the diet. Steller sea lion predation was small relative to total walleye pollock natural mortality, but accounted for a large part of total Atka mackerel natural mortality. Of the bioenergetic, population, and diet parameters, uncertainty in bioenergetic parameters resulted in the largest error in model predictions. The model provided both a quantitative estimate of the Alaskan Steller sea lion population’s food requirements and direction for future research.

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Female attendance patterns and activity budgets of Alaskan Steller sea lions (Eumetopias jubatus) were compared at two sites using scan sampling over two summer breeding seasons in 1994 and 1995 at Sugarloaf Island (a declining population) and Lowrie Island (a stable population). The goal was to document female behaviour and to determine whether there were behavioural differences between the two sites that were consistent with the hypothesis that Steller sea lions in the area of population decline were foodlimited. The perinatal period (time from birth of pup to the mother's first feeding trip) averaged 10.1 days in the area of population decline compared to 8.0 days in the stable area, counter to initial predictions. The first shore visit following the perinatal period was significantly longer in the area of population decline compared to the stable population. Females from both populations exhibited a diel haul out pattern where the majority of returns and departures to and from the rookery occurred between 1800 - 0600 hours. Similarly, the mean length of female foraging trips at both populations increased as their pups grew older, whereas shore visits became shorter. Foraging trips were significantly shorter in the area of population decline, again countering initial predictions. The mean length of maternal foraging trips in the area of population decline was 19.0 hours compared to 25.6 hours for the stable population. In contrast, shore visits and the perinatal period were significantly longer in the area of decline, again countering initial predictions. The mean length of shore visits for the declining population was 26.9 hours compared to 22.6 hours where the population was stable. The average foraging-attendance cycle for both populations was 47.1 hours. Maternal attendance patterns responded in a similar way between years. Activity budgets for the proportion of time spent at sea during daylight observations were consistent with the maternal attendance results. Lactating females in the area of population decline spent less time foraging at sea (35.9 %) than females from the stable population (46.4 %). More time was spent resting ashore in the area of population decline (49.6 %) compared to the stable population (38.9 %). Females from the area of population decline spent more time suckling their pups and were twice as aggressive compared to the females from the stable population. Overall, lactating females from both populations spent a consistent 85 % of their time foraging at sea and resting onshore. Mothers from both populations spent an average of 36.7 % of their total time with pups. A comparison of female Steller sea lions to other female otariid and phocid species showed that the partitioning of activities is related to differences in lactation strategies, social organization, predation, or thermoregulation. Behavioural observations of maternal attendance patterns and activity budgets are not consistent with the hypothesis that Steller sea lions at the declining site in the Gulf of Alaska have greater difficulty obtaining prey compared to the stable population in southeast Alaska.

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Johnstone Strait provides important summer habitat for British Columbia’s northern resident killer whales (Orcinus orca). The site is also an active whale-watching area. A voluntary code of conduct recommends that boaters do not approach whales closer than 100 m to address perceived, rather than demonstrated, effects of boat traffic on killer whales. The purpose of my study was to test the relevance of this guideline. Relationships between boat traffic and whale behaviour were studied in 1995 and 1996 by shore-based theodolite tracking of 25 identifiable focal animals from the population of 209 whales. Individual killer whales were repeatedly tracked in the absence of boats and during approaches by a 5.2 m motorboat that paralleled each whale at 100 m. In addition, whales were tracked opportunistically, when no effort was made to manipulate boat traffic. Dive times, swim speeds, and surface active behaviours such as breaching and spyhopping were recorded. Male killer whales swam significantly faster than females. Whales responded to experimental approaches by adopting a less predictable path than observed during the preceding, no-boat period, although males and females employed subtly different avoidance tactics. Females responded by swimming faster and increasing the angle between successive dives, whereas males maintained their speed and chose a smooth, but less direct, path. Canonical correlations between whale behaviour and vessel proximity are consistent with these conclusions, which suggests that weakening whale-watching guidelines, or not enforcing them, would result in higher levels of disturbance. High variability in whale behaviour underscores the importance of experimental studies when assessing behavioural impacts of human activity on killer whales.

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Vocal dialects have been described in many species, but most studies so far have focused on territorial species such as songbirds and humans. This study investigates patterns of structural variation in the stereotyped calls of 9 matrilineal units of killer whales (Orcinus orca ) with congruent home ranges. In Chapter I, I describe an index of acoustic similarity based on neural network analysis of frequency contours. I test this index on simulated signals, and compare it to similarity ratings from three human subjects. The index could discriminate along global differences in contour frequency, as well as localized differences in frequency and shape. It rated similarity comparably to humans, since differences between ratings among subjects exceeded differences between subject ratings and the neural network index. In the second Chapter, I analyse 2 call types used by 2 groups over a 12 year period to identify mechanisms of vocal differentiation. A test for structural modification detected significant changes in one call type in both groups, but not in the other. The rate of differentiation between both groups was significantly lower for the modified call type than the rate of modification in one group showing that modifications are transmitted between groups. Results of an analysis of structural parameters are consistent with a theory of structural drift.

In Chapter III, I quantify patterns of structural variation for 4 call types shared by 9 matrilineal units. Patterns are consistent across some call types, and similarity ratings for two call types are correlated with the frequency of association among groups. This presents additional evidence for the role of cultural transmission in maintaining structural similarity of shared calls.

This study shows that discrete calls of killer whales are modifiable behavioural traits and transmitted through learning. Since multiple vocal traditions persist in spite of frequent acoustic contact between their members, this study presents evidence for selective copying in resident killer whales. If association patterns reflect kinship among matrilineal units as they do among individuals and among communities, similarity of shared call types indicates the degree of maternal relatedness, and may function in kin recognition or mate choice.

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The goal of this study was to describe aspects of the winter ecology of Steller sea lions (Eumetopias jubatus) from behavioural observations made at a winter haulout between January and April 1996 in Southeast Alaska (Timbered Island, 133° 48’ W, 55° 41’ 45” N). My major hypotheses were: 1) Mothers suckle male offspring more than female offspring, and spend less time on shore to provide for the higher metabolic needs of males. 2) Mothers with yearlings have higher demands than those with pups and should spend more time nursing and more time at sea foraging. Another important goal was to describe the weaning process. Mature females and their dependent young (pups age < 1 y and yearlings 1-2 y) predominated on the winter haulout while, numbers of mature male and sub-adult males remained low. There was considerable variability in numbers of animals on shore from one day to the next. A Drop-one Stepwise regression showed numbers on shore were correlated with weather and sea conditions. The ranked order of important variables included: wave height, air temperature, wind’ speed, wind direction, sky cover, barometric pressure, ocean swell, and tide height. Haul-out patterns were negatively correlated with poor weather and rough sea conditions. No diurnal haul-out pattern was detected. Two measures of maternal investment were made: the time spent suckling by different sex and age class (pups and yearlings), and the time their mothers spent on land and at sea foraging. Differences between the average length of male pup-suckling bouts (x = 37.2 ±2.8 min. SE, n=12) were not significantly longer than female suckling time (x = 35.9 ± 2.3 min., n=12). However, yearlings suckled significantly longer (x = 44.0 ± 2.8 min.SE, n=5) than pups (x = 36.5 ± 1.8 min., n=24). Males spent an average of 33.9% (± 1.1 SE) of the time they were with their mothers onshore suckling compared to 29.9% (± 4.4) by female offspring, but the difference was not statistically significant, and the proportions did not change during the 3 month study period. Average trips to sea by mothers with yearlings lasted 2.3 d (x = 59.7 ± 4.7 h SE, n=6) and were significantly longer than the 1.9 d average trips of mothers with pups (x =48.0 ± 6.3 h, n=18). Mothers with male pups (< 1 y) were away for an average of 2.2 d (x = 52.5 ± 15.2 h SE, n=12) compared to 1.8 d (x = 43.5 ± 12.6 h, n=12) for those with female pups. Mothers spent an average of 35.2 h (± 7.0) on land with male offspring and 34.5 h (± 6.0) with females before departing on foraging trips. Mature females (n=30) showed little seasonal variation in trip duration. Shore visits averaged 19.4 h between trips to sea (n=30, SE=0.90, range 11.2-29.2h). Differences in time spent on shore between offspring genders and age classes were not statistically significant. Lactating females spent an average of 14.2 ± 1.1% SE (n=30) of their time on shore while immature animals spent three times as long (40.2 ± 2.1%). Average rotation time (feeding/resting cycle) from sea to the haulout by mature females was 3.0 days and was consistent through the season. Weaning of pups and juveniles was not observed between January and April. Haul-out patterns during the winter were influenced more by disturbance, sea and weather conditions than by endogenous rhythms.

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In British Columbia the population of harbour seals, Phoca vitulina richardsi, has increased from 9,000 to 135,000 since their protection 25 years ago. Differences in pelage patterns and pupping times suggest that more than one population of harbour seals may be present in the eastern Pacific. Molecular analyses were used to investigate the genetic diversity and population structure of harbour seals along the B.C. coast and in parts of Alaska. The allele frequency at seven microsatellite loci and the haplotypic diversity of the mitochondrial control region (D-loop) were examined. A 475 base pair fragment containing the tRNA proline and part of the mitochondrial control region was amplified and sequenced from 128 animals. Sixty variable sites defined 72 mtDNA haplotypes with pairwise nucleotide differences as high as 5%. Only 14 haplotypes were shared between two or more seals. Some of the more frequent haplotypes were unique to specific areas, while others were distributed over a broad geographic range. Three groups representing the southern Strait of Georgia, southern B.C. and northern B.C./southeast Alaska were observed using parsimony and distance based phylogenetic reconstruction. Additional analyses using sequences from Washington and California revealed the presence of another population comprising the outer coast of Washington, Oregon and California. The order of the clades suggests that the Pacific Ocean was colonized twice. The first invasion occurred approximately 0.67 MYA and represents only a small portion of today's harbour seals in southern Vancouver Island. Seals from the second invasion, about 0.38 MYA, are distributed throughout the Pacific. Analyses of five polymorphic microsatellite loci show that the allele frequency distribution is significantly different in southern British Columbia and northern British Columbia/Alaska. Average heterozygosity was similar for northern and southern populations, however the allelic diversity was higher in the southern population. The migration rate for males based on microsatellite data (3-7 seals1 generation) was higher than that obtained for females from the mtDNA (0.3 females1 generation). This suggests that although migration rates are low they are sufficient to allow gene flow between the two populations.