Robards et al : Variation in fish communities of lower Cook Inlet, Alaska 



967 



Table 2 



Catch-per-unit-of-effort (CPUE) and species diversity indices from nearshore and shelf areas of Kachemak Bay (1976 and 1995-96). 

 Chisik Island, and the Barren Islands. Diversity indices: H' = species diversity; J' = species evenness function; D = species 

 richness (see "Methods" section). 



Location 



Kachemak Bay 

 Kachemak Bay 

 Chisik Island 

 Barren Islands 



CPUE 



H' 



D 



Year 



Nearshore Shelf 



1976 

 1995-96 

 1996 

 1996 



.305 



511 



33 



4506 



345 



92 



821 



Table 3 



Comparison of 1995 and 1996 Kachemak Bay beach seine catches for species that occurred in more than 10^7^ of sets. 



Species 



1995 



1996 



Frequency 

 of capture 



Percent of 

 total catch 



CPUE 



Pacific sand lance 

 Dolly varden 

 Great sculpin 

 Pink salmon 

 Rock sole 

 Pacific cod 

 Pacific herring 

 Whitespotted greenling 

 Tubenose poacher 

 Silverspotted sculpin 



67.2 

 55.7 

 49.2 

 52.5 

 36.9 

 18.9 

 11.5 

 21.3 

 11.5 

 17.2 



60.0 

 1.8 

 0.2 



13.8 

 0.4 

 0.5 



16.5 

 0.1 



>0.1 

 0.1 



250.1 

 7.5 

 1.0 



57.4 

 1.5 

 2.2 



68.8 

 0.5 

 0.2 

 0.5 



The low equitability (J' ) in both time periods reflected 

 dominance by a few species (e.g. sand lance, herrmg) 

 in catches. 



Jaccard's similarity coefficient indicated only mod- 

 erate (59*^) similarity in the presence-absence of 

 species between 1995-96 and 1976. This may have 

 resulted from a combination of 1 ) a dramatic increase 

 in abundance of some species in 1995-96 (e.g. tom- 

 cod, sandfish); and 2) increased fishing effort in 1995- 

 96, which may have increased catches of less com- 

 mon species (e.g. prowfish, Zaprora silenus; capelin) 

 that might have also been detected in 1976, if fish- 

 ing effort had been greater. 



Interannual comparison of beach seine catches in 

 Kachemak Bay: 1995 versus 1996 



As evidenced by catches of common species in 

 Kachemak Bay (Table 3), there was little obvious 



difference in catches between consecutive years. 

 During June and July of 1995, 27,944 fish belonging 

 to 42 species were caught in 60 beach seine sets 

 ( CPUE=466). During the same period in 1996, 50,859 

 fish representing 37 species were found in 122 sets 

 (CPUE=417 ). Forty-four species were identified over 

 the course of the two year study, of which 30 were 

 caught in both years. Species diversity ( H' ) was simi- 

 lar in 1995 and 1996 ( 1.21 and 1.22, respectively), as 

 were species richness (D; 3.61 and 3.43, respectively) 

 and equitability (J'; 0.34 in both years). 



Jaccard's similarity coefficient indicated a 68% 

 similarity between the species assemblages caught 

 in 1995 and 1996. Species not represented in one year 

 or the other were generally uncommon species that 

 were found in only a few seine sets. Differences in 

 percent composition of 1995 and 1996 species assem- 

 blages were not significant (Mann-Whitney rank sum 

 test). 



