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Project Information

Title: Injury to PWS Herring Following the Exxon Valdez Oil Spill

Project Year and Number: 1992: FS11

Other Fiscal Years and Numbers for this Project: 1991: FS11, 1990: FS11, 1989: FS11

Principal Investigator (PI): Evelyn Brown, Alaska Department of Fish & Game

Assisting Personnel: Tim Baker

Research Location: Prince William Sound

Restoration Category: Damage Assessment

Injured Resources Addressed: Pacific Herring

Abstract: Pacific herring, Clupea harengus pallasi, are a major resource in Prince William Sound from both a commercial and ecological perspective. The timing of the Exxon Valdez oil spill overlapped with the annual spring migration of herring spawners to near shore areas. Over 40% of the herring spawning and egg deposition areas, as well as 90% of the summer rearing and feeding areas, were lightly to heavily oiled prior to the spawning events. As a result, herring encountered oil during each of their four life stages in 1989 and, to a lesser extent, in 1990 and 1991. Adult herring traversed areas covered by oil sheens and mousse while traveling northward and eastward in Prince William Sound. Eggs were deposited on oiled shorelines and were "dipped" in sheen through tidal action while incubating. Larvae hatched that contained lipophilic petroleum hydrocarbons in their yolk sacs, and larvae encountered sheen near the surface while in their most sensitive stages. Post-larval or juvenile herring swam through and remained near lightly to heavily oiled shorelines, regularly encountering sheen, mousse and dissolved oil particulates and components through the summer while feeding in shallow near shore bays and passes.

Egg and larval mortality, larval tumors, and other larval injury such as elevated anaphase aberration rates, increased cytogenetic and cytologic anomalies, and morphological abnormalities were much greater in oiled areas than in non-oiled areas in 1989 and 1990. Injuries were more common and more severe in oiled areas than unoiled areas, with injuries declining from 1989 to 1990. The broader ecological implications of the loss of these larvae to the food chain can only be contemplated at this time.

Observed injury to adult herring included stress related hemorrhaging around the vent and enlarged bright gall bladders in 1989, as well as hydrocarbon metabolites throughout the whole fish and its bile. In addition, preliminary data from histopathological examinations revealed that herring captured near and in oiled areas in 1990 suffered increased hepatic lesions in comparison to herring captured in unoiled areas.

The goal of this project is to estimate the injuries accumulating to populations of herring in Prince William Sound. The level of injury needs to be established to evaluate natural restoration processes and to direct restoration activities. A summary of the lethal and sublethal injury will be completed. In addition, accurate and precise estimates of population abundance, age structure, weight, and length composition data will be completed to measure changes at the population level. Sublethal injury to adults will be evaluated and interpreted in terms of potential impacts on the population and reproduction. An intensive modeling effort will be conducted to look at the overall effects of the Exxon Valdez oil spill on the larval and adult components of herring in Prince William Sound.


Geographic Regions Prince William Sound
Species Fish - Herring
Fields of Expertise Biochemistry

Proposal: View PDF (23 KB)

Funding Recommendations: View

Funding Detail For: 1992

Quarterly Project Tasks For: 1992

Annual Report: 1992: Not Applicable

Final Report: View

Publications from this Project: None Available

More information may be available for this project under other years:

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Project Number Proposal Annual Reports Final Report Data
1991: FS11 Not Available 1991: Not Applicable
See Project FS11 See Project FS11
1990: FS11 Not Available 1990: Not Applicable
See Project FS11 See Project FS11
1989: FS11 Not Available 1989: Not Applicable
See Project FS11 See Project FS11