Project Information

Title: Long-term Monitoring of Humpback Whale Predation on Pacific Herring in Prince William Sound 23120114-O

Project Year and Number: 2023: 23120114-O

Other Fiscal Years and Numbers for this Project: 2024: 24120114-O, 2022: 22120114-O, 2021: 21120114-O, 2020: 20120114-O, 2019: 19120114-O, 2018: 18120114-O, 2017: 17120114-O, 2016: 16120114-N, 2015: 15120114-N, 2014: 14120114-N, 2013: 13120114-N, 2012: 12120114-N

Principal Investigator (PI): John Moran (NOAA Fisheries)

Managing Agency: NOAA

Assisting Personnel: None

Project Website: https://gulfwatchalaska.org/monitoring/pelagic-ecosystem/humpback-whales/

Research Location: Prince William Sound

Restoration Category: Monitoring

Injured Resources Addressed: Pacific Herring

Abstract:

The humpback whale monitoring project is part of the Gulf Watch Alaska (GWA) Pelagic Component and the 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 from the Exxon Valdez oil spill (EVOS). 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. Following the Pacific marine heatwave of 2014-2016, humpback whale numbers declined dramatically and calf production fell within PWS. In 2020, we saw a decoupling of whale numbers from herring abundance and an increase in herring biomass while whale numbers remained low. The cause of the decline in PWS whales remains unknown, but the reduction of predators may provide some relief for struggling herring populations. 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 and quality. These data will be combined in an updated bioenergetic model that will allow 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 will contribute to a comprehensive understanding of bottom-up influences and top-down controls on the PWS herring population. This project is one of only two long-term humpback whale projects funded in Alaska, we will continue to inform the Herring Research and Monitoring component of the GWA Long-Term Research and Monitoring program as well as state and federal managers.

This project was approved for the FY22-FY26 funding cycle.


Proposal: View (996 KB)

Reports:
FY23 Annual Report: View (2,496 KB)

Publications from this Project: None Available

Resolutions: