[MARMAM] New paper: Net energy gained by northern fur seals (Callorhinus ursinus) is impacted more by diet quality than by diet diversity

Diaz Gomez, Mariana m.diazgomez at oceans.ubc.ca
Thu Apr 7 11:48:46 PDT 2016

Dear Members,

My co-authors and I would like to bring your attention to our new publication titled "New paper: Net energy gained by northern fur seals (Callorhinus ursinus) is impacted more by diet quality than by diet diversity".
It was recently published in the Canadian Journal of Zoology and you can find it available here:


Abstract: Understanding whether northern fur seals (Callorhinus ursinus (L., 1758)) are negatively affected by changes in prey quality or diversity could provide insights into their on-going population decline in the central Bering Sea. We investigated how six captive female fur seals assimilated energy from eight different diets consisting of four prey species (walleye pollock (Gadus chalcogrammus Pallas, 1814, formerly Theragra chalcogrammus (Pallas, 1814)), Pacific herring (Clupea pallasii Valenciennes in Cuvier and Valenciennes, 1847), capelin (Mallotus villosus (Müller, 1776)), and magister armhook squid (Berryteuthis magister (Berry, 1913))) fed alone or in combination. Net energy was quantified by measuring fecal energy loss, urinary energy loss, and heat increment of feeding. Digestible energy (95.9%–96.7%) was high (reflecting low fecal energy loss) and was negatively affected by ingested mass and dietary protein content. Urinary energy loss (9.3%–26.7%) increased significantly for high-protein diets. Heat increment of feeding (4.3%–12.4%) was significantly lower for high-lipid diets. Overall, net energy gain (57.9%–83.0%) was affected by lipid content and varied significantly across diets. Mixed-species diets did not provide any energetic benefit over single-species diets. Our study demonstrates that diet quality was more important in terms of energy gain than diet diversity. These findings suggest that fur seals consuming low-quality prey in the Bering Sea would be more challenged to obtain sufficient energy to satisfy energetic and metabolic demands, independent of high prey abundance.

Please email me if you have any questions or would like

Mariana Diaz Gomez
M.Sc. Department of Zoology
UBC Marine Mammal Research Unit
Room 215.7, AERL, 2202 Main Mall
Vancouver, B.C. Canada  V6T 1Z4

More information about the MARMAM mailing list