Hoff Biodiversity as an index of regime shift in tlie eastern Bering Sea 



231 



armorhead sculpin (Gymnocanthus galeatus), snailfishes 

 {Liparis gibbus and Careproctus ?-astrinus). marbled eel- 

 pout (Lycodes raridens), and wattled eelpout [Lycodes 

 palearis), and in outer domain species such, as shortfin 

 eelpout (Lycodes brevipes) and sablefish (Anoplopoma 

 fimbria). There has been a increase in large sculpins, 

 including the bigmouth sculpin iHemitripteriis bolini) and 

 the great sculpin (Myoxocephahis polyacanthocephcdus), in 

 the outer domain. The biomass of skates predominantly 

 the Alaska skate (Bathyraja parmifera), increased consid- 

 erably from 1979 through 1990, followed by a prolonged 

 period of little change from 1990 through 2002. 



domain the major portion of the assemblage comprises 

 3-5 species. Figure 3 shows the change in biodiversity 

 indexes from 1975 to 2002 for each domain separately 

 and all domains combined. The piecewise model shows a 

 period of inflection for evenness and richness indexes for 

 flatfish in the inner and middle domains that occurred 

 between 1987 and 1993, with the average year of inflec- 

 tion being 1990 (Fig. 3, Table 3). The outer domain for 

 flatfish showed little change in evenness and richness 

 throughout the 24-year study period. Three species 

 dominated the entire period, with somewhat evenly 

 distributed biomass proportions. 



Flatfish biodiversity 



Eleven species or species groups were used for biodi- 

 versity indexes for the flatfish guild (Table 1). All 11 

 species are rarely found together, and within each shelf 



Roundfish biodiversity 



Forty-one species or species groups were used in the 

 roundfish biodiversity analysis (Table 2). The even- 

 ness and species richness index for the roundfish group 



