Title: Long-term Monitoring of Humpback Whale Predation on Pacific Herring in Prince William Sound
Project Year and Number: 2019: 19120114-O
Other Fiscal Years and Numbers for this Project: None
Principal Investigator (PI): John Moran, NMFS/Auke Bay Laboratories
Assisting Personnel: Jan Straley
Restoration Category: Monitoring
Abstract: The humpback whale monitoring project is part of the Gulf Watch Alaska (GWA) pelagic component’s integrated predator-prey survey. Humpback whale predation has been identified as a significant source of mortality on over-wintering Pacific herring in Prince William Sound (PWS) and a likely top-down force constraining their recovery. Humpback whales in PWS have a higher percentage of herring in their diet and forage longer on herring during non-summer months than their counterparts in Southeast Alaska. Currently, North Pacific humpback whales in the Gulf of Alaska may be experiencing nutritional stress and increased use of inland waters like PWS could result in increased predation on herring. We will continue to evaluate the impact by humpback whales foraging on Pacific herring populations in PWS following protocols established during 2007/08 and 2008/09 (EVOSTC project PJ090804). Prey selection by humpback whales is determined through acoustic surveys, visual observation, scat analysis, and prey sampling. Chemical analyses of skin and blubber biopsy samples provide a longer term perspective on shifts in prey type (trophic level from stable isotopes) and quality (energy content). These data are combined in an updated bioenergetic model that allows us to assess the impact of recovering humpback whale populations on the PWS ecosystem. By integrating with the forage fish and fall/winter marine bird components, we contribute to a comprehensive understanding of bottom-up influences and top-down controls on the PWS herring population. Our project has conducted three cruises per year: a September cruise funded by GWA, and December and March cruises funded ($100K) by NOAA Alaska Fisheries Science Center. The December and March surveys during FY19-21 will no longer be funded by NOAA. Our research has demonstrated that humpback whale predation on herring peaks in the fall and spring when fish are aggregated. With the fall survey funded by GWA, we are requesting additional funding to maintain the spring cruise. A spring survey, in particular, provides an important assessment of whale abundance and predator-directed impact on pre-spawning herring schools.
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Proposal: View PDF (302 KB)
Funding Recommendations: View
Funding Detail For: 2019
Quarterly Project Tasks For: 2019
Annual Report: 2019: Due 03/01/2020
Final Report: Draft Final Report Due 4/15/20
Publications from this Project: None Available