Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8993
Title: Spatio-temporal models reveal subtle changes to demersal communities following the Exxon Valdez oil spill
Author: Andrew O. Shelton, Mary E. Hunsicker, E. J. Ward, Blake E. Feist, Rachael Blake, Colette L. Ward, Benjamin Williams, Janet T. Duffy-Anderson, Anne Hollowed, Alan C. Haynie
Publication Year: 2017
Journal: ICES Journal of Marine Science
Keywords: exxon valdez,Groundfish,Alaska,spatio-temporal,community analysis

Toxic pollutants such as crude oil have direct negative effects for a wide array of marine life. While mortality from acute exposure to oil is obvious, sub-lethal consequences of exposure to petroleum derivatives for growth and reproduction may be less evident. However, sub-lethal effects in fish populations are obscured by natural environmental variation, fishing, and measurement error. We use fisheries independent surveys in the Gulf of Alaska to examine the consequences of the 1989 Exxon Valdez oil spill (EVOS) for demersal fish. We delineate areas across a range of exposure to EVOS and use spatio-temporal models to quantify the abundance of 53 species-groups over 31 years. We compare multiple community metrics for demersal fish in EVOS and Control areas. We find that areas more exposed to EVOS have more negative trends in total groundfish biomass than non-EVOS areas, and that this change is driven primarily by reductions in the abundance of the apex predator guild. We show no signature of increased variability or increased levels of synchrony within EVOS areas. Our analysis supports mild consequences of EVOS for groundfish communities, but suggests that long time-series and assessments of changes at the community level may reveal sub-lethal effects in marine communities.

Theme: Ecosystem approach to improve management of marine resources
Foci: Describe the interaction between human activities, particularly harvest of marine resources, and ecosystem function.
Provide scientific support for the implementation of ecosystem-based management