Alaska SeaLife Center Researchers Work to Determine Necessary Protocols for Restoration of Prince William Sound Herring
The Alaska Department of Fish and Game banned herring fishing in Prince William Sound after the Exxon Valdez Oil Spill in 1989, again from 1993 through 1996, and yet again from 1996 through 2007, each time halting local fishing industries. The halted fisheries were most recently valued at some $7 million.
The Exxon Valdez Oil Spill Trustee Council has classified the Prince William Sound population of Pacific herring as a resource that has not recovered. Reasons for the population collapse and failure to recover remain unknown.
Now, 18 years after the spill, Alaska SeaLife Center researchers are working with Maine-based MariCal to test factors that affect herring recruitment, or their ability to grow and survive until they reach reproductive age. This research will help build understanding of how to culture and release juvenile herring to aid in stock restoration. One day, knowledge gained at the center could be used to supplement herring numbers in Prince William Sound.
Previous studies indicate that herring numbers were affected by the Exxon Valdez Oil spill in 1989, but the continuing effects of the spill are unclear. Herring populations in Prince William Sound increased in the late 1970s before peaking at 100,000 tons annually between 1989, the year of the spill, and 1993, but then declined significantly, and are now similar to numbers observed in the 1970s.
Diseases such as viral hemorrhagic septicemia and Icthyophonus might be part of the explanation for herring decline. Additionally, predation and environmental factors including warming and less saline ocean waters, increased pollution, and poor forage conditions may also play a role.
Researchers working at the Alaska SeaLife Center are testing some of these factors to understand how to culture and care for herring successfully. “We are aiming to take a step to fulfill stakeholder needs for a restored herring resource and learn from the effort,” says Howard Ferren, assistant director for research operations at the center.
Specifically, researchers are working to optimize conditions of salinity, temperature, food, and other factors to maximize the survival of juvenile herring raised in captivity. Researchers at the SeaLife Center are also studying ways to optimize lipid, or fat, storage in juvenile herring, which could help herring survive winters easier.
Herring restoration, next steps
Pacific herring are an ecologically and commercially important species. As high lipid (or high fat) fish, they provide high quality food for other species, and they are a traditionally important part of a community based, sustainable fishery throughout the spill area.
If researchers can determine optimum conditions, minimize potential threats such as disease, and meet targets for juvenile fish production, the next step may be to work with other stakeholders to restore pre-Exxon Valdez oil spill numbers of herring.
The SeaLife Center has received $85,000 for the initial year study with a pending two-year $1.9 million investigation to follow if the EVOS Trustee Council elects to take a supplementation feasibility analysis path that could lead to a larger pilot-scale herring supplementation program in Prince William Sound.
The Alaska SeaLife Center is a non-profit marine science facility dedicated to understanding, maintaining, and conserving the marine ecosystem of Alaska and the North Pacific through research, rehabilitation, conservation and public education. The Center’s research facilities and naturalistic exhibits immerse visitors in the dynamic marine ecosystems of Alaska. Learn more at http://www.alaskasealife.org