Scale-dependent interactions of Mediterranean whales with marine dynamics

We investigated the influence of the ocean circulation at different spatiotemporal scales on the seasonal distribution of a large marine predator, the Mediterranean fin whale, by comparing multisatellite data with the positions of eight fin whales equipped with Argos tracking devices from August 2003 to June 2004. At the western Mediterranean basin scale, fin whales were associated with the anticlockwise gyre in the northern part of the western Mediterranean Sea, which defines the habitat of krill, the whales' main prey. At mesoscale and submesoscale, and only during the seasonal phytoplankton biomass minimum in summer, whales exhibited a preference for the periphery of eddies and they were often associated with filaments indicative of submesoscale fronts. Timescales of these mesoscale and submesoscale features are comparable with the ecological timescales of the lower levels of the trophic chain. Whales were not associated to productive areas, probably due to the spatiotemporal lag between phytoplankton and krill. Our results suggest that stirring by eddies may create filaments that are favorable foraging grounds for predators searching for aggregated prey during the most oligotrophic period of the year.