BALEEN WHALE DISTRIBUTION RELATIVE TO SURFACE TEMPERATURE AND ZOOPLANKTON ABUNDANCE OFF SOUTHERN CALIFORNIA, 2004-2008

We investigated the spatial and temporal variation in distributions of three large baleen whale species off southern California in relation to sea surface temperature (SST) and zooplankton displacement volume using Geographic Information System (GIS) software Data were collected on sixteen California Cooperative Oceanic Fisheries Investigations (CalCOFI) quarterly cruises (lines 77-93) from July 2004 March 2008 The most frequently sighted large whales were humpback whales (Megaptera novaeangliae, 67 sightings), fin whales (Balaenoptera physalus, 52 sightings), and blue whales (Balaenoptera musculus, 36 sightings) Blue and humpback whale sightings peaked in summer (July/August) and fin whales were most frequently seen in summer and fall, consistent with known migratory patterns In spring through fall, whale sighting locations were associated with colder SST and greater zooplankton abundance levels compared to averages from random locations on the trackline These results support the hypothesis that foraging distributions of large whales are linked to cold surface temperatures, which may indicate processes that enhance prey production and accumulation, such as upwelling or advection of productive water within the California Current However, winter distributions of whales presumed to be migrating do not appear to be related to the habitat variables we analyzed, and may be harder to predict based on oceanographic data The frequency of CalCOFI cruises provides us with high temporal resolution and an ongoing, long time series compared to other survey efforts, allowing comparison between seasons and years that will increase our understanding of these top predators and their response to habitat variability within an important subregion of the California Current Ecosystem