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Marine Mammal Research News:

A Window into the Lives of Resident Killer Whales

This summer, a team of researchers from the University of British Columbia, together with the Hakai Institute, set out to determine how fish-eating killer whales find their food, and whether there is a shortage of Chinook salmon available to killer whales in the Salish Sea.  Here is a peek into what the researchers saw.


Growth and development of North Pacific gray whales (Eschrichtius robustus).
Agbayani, S., S.M.E. Fortune and A.W. Trites. 2020.
Journal of Mammalogy, DOI:10.1093/jmammal/gyaa028
Understanding variability in growth patterns of marine mammals provides insights into the health of individuals and status of populations. Body growth of gray whales (Eschrichtius robustus) has been described for particular life stages, but has not been quantified across all ages. We derived a comprehensive growth equation for gray whales by fitting a two-phased growth model to age-specific length data of eastern North Pacific gray whales that were captured, stranded, or harvested between 1926 and 1997. To predict mass-at-age, we used the allometric relationship between mass and length. We found that on average (± SD), calves were 4.6 ± 0.094 m and 972 ± 27 kg at birth, and reached 8.53 ± 0.098 m and 7,645 ± 162 kg by the end of their first year of life (n = 118). Thus, calves almost double (2×) in length and octuple (8×) in mass while nursing, and are effectively about two-thirds of their asymptotic adult length and one-third of their maximum mass when weaned. The large sample of aged individuals (n = 730) indicates that gray whales live up to ~48 years and have a life expectancy of < 30 years. Adult females attain a mean (± SD) asymptotic size of 13.2 ± 0.054 m and 20,706 ± 249 kg, while the smaller males average 12.6 ± 0.054 m and 19,812 ± 249 kg at ~40 years of age. Females are thereby ~4% longer and heavier than males. These age-specific estimates of body size can be used to estimate food requirements and assess nutritional status of individuals.

keywords     eastern gray whale, growth curves, length, life expectancy, longevity, mass, morphometrics, Putter model, sexual dimorphism
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The genome of the Steller sea lion (Eumetopias jubatus).
Kwan, H.H., L. Culibrk, G.A. Taylor, S. Leelakumari, R. Tan, S.D. Jackman, K. Tse, T. MacLeod, D. Cheng, E. Chuah, H. Kirk, P. Pandoh, R. Carlsen, Y. Zhao, A.J. Mungall, R. Moore, I. Birol, M.A. Marra, D.A.S. Rosen, M. Haulena and S.J.M. Jones. 2019.
Genes Vol 10(486):doiorg/103390/genes10070486.
The Steller sea lion is the largest member of the Otariidae family and is found in the coastal waters of the northern Pacific Rim. Here, we present the Steller sea lion genome, determined through DNA sequencing approaches that utilized microfluidic partitioning library construction, as well as nanopore technologies. These methods constructed a highly contiguous assembly with a scaffold N50 length of over 14 megabases, a contig N50 length of over 242 kilobases and a total length of 2.404 gigabases. As a measure of completeness, 95.1% of 4104 highly conserved mammalian genes were found to be complete within the assembly. Further annotation identified 19,668 protein coding genes. The assembled genome sequence and underlying sequence data can be found at the National Center for Biotechnology Information (NCBI) under the BioProject accession number PRJNA475770.

keywords     Steller sea lion, genetics
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