Dr Andrew Trites
An analysis of historic (1908-1967) whaling records from British Columbia, Canada.
This work is an analysis of historic whaling records from British Columbia, Canada. From 1908 to 1967 the whaling industry sought sei (Balaenoptera borealis), fin (Balaenoptera physalus), humpback (Megaptera novaeangliae), blue (Balaenoptera musculus) and sperm (Physeter macrocephalus) whales. They took over 24,000 whales during this period and recorded a number of variables for each capture such as species, length, sex and date of kill. A large portion of the records (n=8,164 whales) also include the location of the kill.
This rich database has never before been explored in any detail, yet contains valuable information about the natural history (e.g. timing of migration, seasonal distribution) of these whale species and the effects of whaling (e.g. reduced reproduction, local extirpation) on the populations that frequented the coastal waters of British Columbia. The data also provide insights into where the great whales were once found, and a means to describe and identify regions of potentially critical habitat.
The goal of my study was to develop a predictive model of whale distributions and use it to identify whale habitat for the five species that dominated the British Columbia catch record. I also wanted to identify any seasonal and annual trends which would help describe the seasonal movements and long term population level effects of whaling on each of these species. Chapter One addresses the trends in the whaling records and examines the biases due to nonsystematic data collection. Attention is paid to disentangling the biological significance from the regulatory, socioeconomic and technological factors that may bias the interpretation.
I relate the monthly trends to existing literature, providing insight into the migration patterns and population structure of the great whales in the Northeast Pacific Ocean. I present the habitat models in Chapter Two, along with a new methodology and software tool developed to support the model building. The methods required a detailed analysis of the relationship between the species under investigation and six potential predictor variables (depth, 2 slope, depth class, temperature, salinity and month).
This resulted in three, multi-panel figures for each species, totaling 165 panels contained in 15 figures. While these figures are fundamental to the model development, they are presented in Appendix A: Presence-Absence Scatter Plots to improve the readability of the text. After exploring the relationships between the predictor variables and each individual species, I generated probability distributions for each species in the study using generalized linear models. These probabilities, which I interpreted as habitat preferences, allowed me to propose some hypotheses about why these predicted habitats might be attractive to the great whales that once frequented British Columbia waters.
An analysis of historic (1908-1967) whaling records from British Columbia, Canada. Gregr, E.J. 2000. MSc thesis, University of British Columbia, Vancouver, BC. 104 pages (PDF)
A novel presence-only validation technique for improved Steller sea lion Eumetopias jubatus critical habitat descriptions. Gregr, E.J. and A.W. Trites. 2008. Marine Ecology Progress Series 365:247-261. (PDF)
Economic valuation of critical habitat closures. Berman, M., E.J. Gregr, G. Ishimura, R. Coatta, R. Flinn, U.R. Sumaila and A.W. Trites. 2008. In Fisheries Centre Research Reports. Vol 16(8) pp. 102 (PDF)
Bottom-up forcing and the decline of Steller sea lions (Eumetopias jubatus) in Alaska: assessing the ocean climate hypothesis.Trites, A. W., A. J. Miller, H. D. G. Maschner, M. A. Alexander, S. J. Bograd, J. A. Calder, A. Capotondi, K. O. Coyle, E. D. Lorenzo, B. P. Finney, E. J. Gregr, C. E. Grosch, S. R. Hare, G. L. Hunt, J. Jahncke, N. B. Kachel, H.-J. Kim, C. Ladd, N. J. Mantua, C. Marzban, W. Maslowski, R. Mendelssohn, D. J. Neilson, S. R. Okkonen, J. E. Overland, K. L. Reedy-Maschner, T. C. Royer, F. B. Schwing, J. X. L. Wang and A. J. Winship. 2007. Fisheries Oceanography 16:46-67.(PDF)
Killer whales, whaling and sequential megafaunal collapse in the North Pacific: a comparative analysis of the dynamics of marine mammals in Alaska and British Columbia following commercial whaling.
Trites, A. W., V. B. Deecke, E. J. Gregr, J. K. B. Ford, and P. F. Olesiuk. 2007. Marine Mammal Science 23:751-765. (PDF)