Chang Effects of sewage sludge dumping on fishery resources 



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Analyses of red hake data are used here as an ex- 

 ample of a detailed interpretation of temporal differ- 

 ences in species CPUE. (Black sea bass could be equally 

 well used because of its similar pattern of CPUE indi- 

 ces.! Species test statistics for red hake revealed sig- 

 nificant temporal differences in CPUE indices both by 

 weight (biomass) and number of individuals in the 

 south, but not in the north region (Table 1). Biomass 

 indices declined from pre-dumping spring cruises to 

 post-dumping spring cruises (Table 4). Numerical abun- 

 dance indices also declined from pre-dumping spring 

 cruises to post-dumping spring cruises (Table 5). Red 

 hake autumn data were also analyzed, but the species 

 test statistics were not significant (Table 1). Biomass 

 indices (Table 6) and number indices (Table 7) declined 

 from the pre-dumping to the post-dumping period. 

 These negative temporal differences for red hake are 

 interpreted as an indication of significant reduction in 

 abundance over time. 



CPUE test statistics for several other species also 

 suggest significant temporal differences between pre- 



and post-dumping periods. The number of significant 

 differences was greater for spring cruises than for au- 

 tumn cruises (Table 1). Biomass indices were relatively 

 low for both spring and autumn cruises in both north 

 and south regions generally, with the exception of high 

 values for dogfish (Tables 4 and 6). Species number 

 indices were mixed (Tables 5 and 7). 



Test statistics for summer flounder and sea scallop 

 CPUE by weight and number for the spring cruises 

 were significantly different in the southern region. In 

 the northern region, only summer flounder biomass 

 and scallop number indices were significantly differ- 

 ent. Indices for summer flounder and sea scallop for 

 autumn cruises, however, failed to be significant in 

 either region (Table 1). Summer flounder abundance 

 indices of both biomass and number indicate a decline 

 from the pre-dumping period to the post-dumping pe- 

 riod, while both indices for the sea scallop increased 

 (Tables 5 and 7). This suggests a decline (negative 

 differences) over time for summer flounder, and an 

 enhancement (positive differences) for sea scallop. 



