Seabird Predation on Herring in Prince William Sound

 

In Alaska, most studies on seabirds and prey fish have been conducted in the summer, and have focused on the effect of fish abundance and quality on seabird productivity.  However winter is the most energetically-demanding time of year for seabirds due to colder weather, reduced day length and food scarcity.

 

At the Prince William Sound Science Center we are studying the winter distribution and abundance of seabirds in PWS in relation to herring.  Herring form large schools and may be found in a number of fjords and bays within PWS.  Our surveys are conducted simultaneously with hydroacoustic surveys of herring. 

Fish are also sampled to verify species and age. This study aims to establish which seabirds are feeding on adults and juvenile herring and to evaluate the potential impacts of seabird predation on herring.  From a fisheries management standpoint, this study will provide data on bird consumption that can be used by managers to more realistically model herring recruitment. 

 

Seabird Interactions with Marine Mammals

 

We are also investigating whether marine mammals foraging on herring enhance feeding opportunities for seabirds.  Diving whales and sea lions drive fish to the surface and break up schools, making them more available to birds.  Since winter 2007-08, a seabird observer has conducted surveys in conjunction with all winter humpback whale censuses in Prince William Sound.  These surveys aim to provide a greater understanding of the factors influencing winter seabird distribution. 

Co-Principal Investigators

Mary Anne Bishop, Ph.D.

PWS Science Center

mbishop@pwssc.org

 

Kathleen Kuletz, Ph.D.

US Fish & Wildlife Service

Kathy_Kuletz@fws.gov

 

Funding

Exxon Valdez Oil Spill Trustee Council

An echogram displaying seabird predation on herring in Port Gravina, March 2007

Humpback Whale with foraging Black-legged Kittiwakes