Possible effects of pollock and herring on the growth and reproductive success of Steller sea lions : insights from feeding experiments using an alternative animal model, Rattus norvegicus ...

• Main Author: Donnelly, Carolyn Patricia
• Format: Text
• Language: English
• Published: University of British Columbia 2009
• Subjects: Theragra chalcogramma; Alaska
• Online Access: https://dx.doi.org/10.14288/1.0074855; https://doi.library.ubc.ca/10.14288/1.0074855

The decline of Steller sea lions (Eumetopias jubatus) in the Gulf of Alaska appears to have been associated with a switch of diet from 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 norvegicus, 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 ...