El Niño Effects on Pinnipeds in Peru
The South American fur seal (Arctocephalus australis) and the South American sea lion (Otaria byronia) are the only two species of pinniped exploiting the rich Peruvian upwelling system. Both, like most other pelagic feeding vertebrates in Peru, feed largely on anchovy (Engraulis ringens), a small clupeid fish which previous to 1973 occurred in abundance in this system (Idyll 1973). Because of the economic importance of anchovy to the Peruvian fishing industry, the biology of anchovy and the effects of El Niño (EN) on its distribution and abundance have been relatively well documented (Glantz and Thompson 1981; Cushing 1982; Pauly and Tsukayama 1987) and thus it is possible to understand how EN events affect the seals’ prey availability. Here, I shall compare the foraging behaviour, diet, pup growth and mortality of the fur seals and sea lions in Peru under EN and non-EN conditions and examine whether the differences can be explained by the changes in anchovy availability known to take place during ENs. Greater emphasis will be placed on the fur seals because there is only limited information on sea lions in Peru.
KeywordsTrip Duration Diving Behaviour Dive Depth Deep Dive Forage Trip Duration
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