Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

This study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale (Balaenoptera physalus) in the estuary and the gulf of St. Lawrence (eastern Canada). Specifically, we here examine the trophic niche specialisation of fin whales, at the individual and population levels using both Fatty acid trophic markers and stable isotopes, during a known ecosystem shift in the EGSL. We examined skin biopsies from 99 fin whales sampled in the St. Lawrence Estuary (Canada) over a nine year period (1998—2006) during which environmental change was documented. We analyzed stable isotope ratios in skin and fatty acid signatures in blubber samples of whales, as well as in seven potential prey species throughout the estuary and the gulf of St. Lawrence.