Biodiversity as an Index of Regime Shift in the Eastern Bering Sea

Abstract

"Data collected from an annual groundfish survey of the eastern Bering Sea shelf from 1975 to 2002 were used to estimate biomass and biodiversity indexes for two fish guilds: flatfish and roundfish. Biomass estimates indicated that several species of flatfish (particularly rock sole, arrowtooth flounder, and flathead sole), several large sculpins (Myoxocephalus spp.), bigmouth (Hemitripterus bolini), and skates (Bathyraja spp.) had increased. Declining species included several flatfish species and many smaller roundfish species of sculpins, eelpouts (Lycodes spp.), and sablefish (Anoplopoma fimbria). Biodiversity indexes were calculated by using biomass estimates for both guilds from 1975 through 2002 within three physical domains on the eastern Bering Sea shelf. Biodiversity trends were found to be generally declining within the roundfish guild and generally increasing within the flatfish guild and varied between inner, middle, and outer shelf domains. The trends in biodiversity indexes from this study correlated strongly with the regime shift reported for the late 1970s and 1980s."