This study addressed the lack of recovery of Pacific herring (Clupea pallasii) in Prince William Sound, Alaska, in relation to humpback whale (Megaptera novaeangliae) predation.This study addressed the lack of recovery of Pacific herring (Clupea pallasii) in Prince William Sound, Alaska, in relation to humpback whale (Megaptera novaeangliae) predation. As humpback whales rebound from commercial whaling, their ability to influence their prey through top-down forcing increases. We compared the potential influence of foraging humpback whales on three herring populations in the coastal Gulf of Alaska: Prince William Sound, Lynn Canal, and Sitka Sound (133–147°W; 57–61°N) from 2007 to 2009. Information on whale distribution, abundance, diet and the availability of herring as potential prey were used to correlate populations of overwintering herring and humpback whales. In Prince William Sound, the presence of whales coincided with the peak of herring abundance, allowing whales to maximize the consumption of overwintering herring prior to their southern migration. In Lynn Canal and Sitka Sound peak attendance of whales occurred earlier, in the fall, before the herring had completely moved into the areas, hence, there was less opportunity for predation to influence herring populations. North Pacific humpback whales in the Gulf of Alaska may be experiencing nutritional stress from reaching or exceeding carrying capacity, or oceanic conditions may have changed sufficiently to alter the prey base. Intraspecific competition for food may make it harder for humpback whales to meet their annual energetic needs. To meet their energetic demands whales may need to lengthen their time feeding in the northern latitudes or by skipping the annual migration altogether. If humpback whales extended their time feeding in Alaskan waters during the winter months, the result would likely be an increase in herring predationAll humpback whale photographic data collected was authorized under scientific research permits 473-1700-01 and 782-1719 issued to Janice M. Straley and the National Marine Mammal Lab, respectively, from NOAA, Office of Protected Resources, WA, DC. In addition, this research was conducted with the authorization 08-07 of the Institutional Animal Care and Use Committee (IACUC), University of Alaska Fairbanks. Special thanks to D. Janka, and his knowledge of Prince William Sound and all the crew that joined us on our surveys. Also, thanks to Jennifer Cedarleaf, Ellen Chenoweth, Keith Cox, Suzie Teerlink, Fletcher Sewall, and others that assisted on surveys in Sitka Sound and Lynn Canal.
Thanks to the Captains and crews of the NOAA Vessel John N Cobb, M/V Auklet, M/V Steller, and M/V Alaskan Adventurer, Heather Riley, Neil Dawson, Jennifer Cedarleaf, Ellen Chenoweth, Kate McLaughlin, Andy McLaughlin, Craig Matkin, Olga von Ziegesar, Fletcher Sewall, John Hudson, Keith Cox, Prince William Sound Science Center and Alaska Department of Fish and Game, Cordova. Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. The findings and conclusions of this paper are those of the authors and do not necessarily represent the views of the National Marine Fisheries Service. The Exxon Valdez Oil Spill Trustee Council (award NA17NMF4720027) supported the research described in this paper. However, the findings and conclusions presented by the author(s) are their own and do not necessarily reflect the views or position the Trustee Council. The authors disclose there was no actual or potential conflict of interest including any financial, personal, or other relationships with other people or organizations within three years of beginning the submitted work that could inappropriately influence, or be perceived to influence, their work.Ye
