CLARK and BROWN: CHANGES IN BIOMASS OF FINFISHES AND SQUIDS 



M-ddle AltantK 



— — So New England 



Georges Bonk 



Gulf of Mome 



FIGURE 8. — Catch of other pelagics and other fish in U.S. au- 

 tumn bottom trawl surveys for the Middle Atlantic (strata GI- 

 TS), 1967-74, and for southern New England (strata 1-12), 

 Georges Bank (strata 13-25), and the Gulf of Maine (strata 26-30 

 and 36-40), 1963-74. 



over 90% for certain species, while for all data 

 combined we obtained declines of 74%, 52%, 37%, 

 and 41% for the Middle Atlantic, southern New 

 England, Georges Bank, and Gulf of Maine areas, 

 respectively. Omission of catches of searobins for 

 the Middle Atlantic area, however, reduces that 

 value to 52%. Further omitting data for squid for 

 all strata sets (as squid catches were inadequately 

 recorded during the early years of the survey) 

 provides corresponding declines of 62% , 58% , 38% , 

 and 41%. Consequently, even greater declines 

 may be more realistic than those initially com- 

 puted. 



After examining data for the above strata sets, 

 we evaluated trends for the entire region by 

 combining data over all strata (Tables 8, 9) and 

 compared between means of initial and final 

 periods (1967-68/1973-74 data for all strata; 

 1963-65/1972-74 data, Middle Atlantic strata 

 excluded). For 1967-74, all strata (Table 8), we 

 observed a decline of 32%, while for 1963-74, 



FIGURE 9. — Catch of squid in U.S. autumn bottom trawl surveys 

 for the Middle Atlantic (strata 61-76), 1967-74, and for southern 

 New England (strata 1-12), Georges Bank (strata 13-25), and the 

 Gulf of Maine (strata 26-30 and 36-40), 1963-74. 



58 69 



YEAR 



FIGURE 10.— Catch of total finfish and squid in U.S. autumn 

 bottom trawl surveys for the Middle Atlantic (strata 61-76), 

 1967-74, and for southern New England (strata 1-12), Georges 

 Bank (strata 13-25), and the Gulf of Maine (strata 26-30 and 

 36-40), 1963-74. 



Middle Atlantic strata excluded (Table 9), the 

 decline is 43% . The corresponding figures are 37% 

 and 46%, respectively, with squid omitted. 



The above data demonstrate that significant 

 changes in biomass levels occurred in SA 5 and 6 

 after the early 1960's. It will be noted, however, 

 that the summaries presented above are biased by 

 "catchability" differences among species and do 



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