Symposium Abstract: Biodiversity Changes in Space and Time in the Gulf of Alaska: An Ecosystem Measure of Fishing Effects on Habitat
R. F. Reuter and S. Gaichas
Ecosystem resilience, in theory, is related to species and habitat diversity. It is believed that high diversity in a system may act as ‘insurance’ against any type of disturbance. Disturbance from fishing activities may result in diversity changes through time by the removal of select species and by gear effects on the bottom habitats. Historical bottom trawl survey data can be used to assess changes in diversity in the Gulf of Alaska. Survey data collected between 1960 and 2001 was used to map and biologically classify benthic habitats in terms of species diversity for different classes of marine animals. Although identification of benthic invertebrate species was limited by changing survey priorities, groundfish species such as rockfish and flatfish that occupy distinct habitat types were also used to classify areas. A wide variety of diversity indices are available and in this study several were explored. Maps of species diversity from pre-fishing trawl surveys were created using a geographical information system (GIS) and used to indicate historically important habitats. Inclusion of fishery observer data, when analyzing these maps, may indicate possible fishery effects in heavily fished areas, and suggest natural rates of change in less fished areas. This study will complement more direct experimental approaches for assessing fishing effects on benthic habitat by establishing the historical context of variability in an ecosystem.