CLARK and BROWN: CHANGES IN BIOMASS OF FINFISHES AND SQUIDS 



the basis of stock structure, ecological factors, 

 exploitation patterns, and availability of survey 

 data. In the present paper, we have selected four 

 major strata sets in SA 5 and 6 based on the above 

 factors (Figure 1) which we considered separately 

 prior to examination of data for the area as a 

 whole. These are as follows: 



1. Middle Atlantic area (strata 61-76, cor- 

 responding approximately to ICNAF Di- 

 visions 6B and C); 



2. Southern New England area (strata 1-12, 

 corresponding approximately to ICNAF 

 Divisions 6A and Subdivision 5Zw); 



3. Georges Bank (strata 13-25, corresponding 

 approximately to ICNAF Subdivision 5Ze), 

 and 



4. Gulf of Maine (strata 26-30 and 36-40, 

 corresponding approximately to ICNAF 

 Division 5Y). 



The rationale for this arrangement is based on 

 differences in faunal assemblages although 

 exploitation patterns and data availability were 

 also considered. A number of stock identification 

 studies support such an arrangement (Wise 1962; 

 Grosslein 1962; Anthony and Boyar 1968; Ridg- 

 way et al. 13 ; Anderson 14 ; and others). In addition, 



Grosslein's 15 study indicated a relatively high 

 diversity of species in the southern New 

 England-Middle Atlantic areas in contrast to the 

 Gulf of Maine, with Georges Bank being a rather 

 transitional area. Exploitation patterns and 

 reporting of commercial fishery statistics also 

 dictate some form of division between Subdivision 

 5Ze and the Subdivision 5Zw-Statistical Area 6 

 region and other areas to the north or south (Fig- 

 ure 1). Finally, the fact that survey data are 

 nonexistent for Middle Atlantic strata prior to 

 1967 required a division between this area and the 

 remainder of SA 5 and 6 for analytical purposes. 

 Trends in relative abundance from 1963 to 1974 

 (stratified mean catch per tow [kilograms], U.S. 

 autumn bottom trawl survey data) are given by 

 area for selected species in Tables 2-5 and for 

 major ICNAF categories in Figures 4-9. Pro- 

 nounced declines of principal groundfish are 

 evident both on Georges Bank and in the Gulf of 

 Maine, with lesser declines in the remaining areas 

 (Figure 4). The trends observed resulted primarily 

 from declining relative abundance of haddock and 

 silver and red hake (Tables 2-5). Haddock, in 

 particular, appears to have greatly decreased on 



13 Ridgway, G. J., R. D. Lewis, and S. Sherburne. 1969. 

 Serological and biochemical studies of herring populations in the 

 Gulf of Maine. Cons. Perm. Int. Explor. Mer, Memo No. 24, 6 p. 



14 Anderson, E. D. 1974. Comments on the delineation of red 

 and silver hake stocks in ICNAF Subarea 5 and Statistical Area 

 6. Int. Comm. Northwest Atl. Fish. Annu. Meet. 1974, Res. Doc. 

 No. 100, Serial No. 3336 (mimeo.), 8 p. 



15 Grosslein, M. D. 1973. Mixture of species in Subareas 5 and 

 6. Int. Comm. Northwest Atl. Fish. Annu. Meet. 1973, Res. Doc. 

 No. 9, Serial No. 2911 (mimeo.), 20 p. 



TABLE 2. — Stratified mean catch per tow (kilograms) for selected species of finfish and squid, 

 Albatross IV autumn bottom trawl survey data, 1967-74, Middle Atlantic area (strata 61-76). 



Species 



1967 



1968 



1969 



1970 



1971 



1972 



1973 



1974 



Principal groundfish: 



Silver hake 0.9 0.9 0.1 0.2 0.3 0.5 0.4 '0.0 



Red hake 0.1 0.8 0.5 0.2 0.4 0.2 0.1 0.0 



Flounders: 



Yellowtail 3.4 5.5 3.6 '0.0 0.3 0.1 1 0.0 0.0 



Winter flounder 1.7 1.3 0.6 1 0.0 0.2 0.1 0.1 0.0 



Summer flounder 2.0 1.5 0.8 '0.0 0.4 0.1 0.3 0.8 



Other 0.7 2.0 0.6 4 0.8 10 1.6 0.5 



Other groundfish: 



Angler 0.7 0.6 0.3 '0.0 0.1 1.4 0.9 '0.0 



Scup 2.6 0.8 8.4 0.1 0.3 3.2 0.2 0.7 



Searobins 130.1 13.8 5.4 6.9 3.1 1.7 1.9 1.9 



Other 05 0.3 0.3 '0.0 '0.0 '0.0 '0.0 0.0 



Principal pelagics: 



Herring 0.0 0.0 0.0 0.0 0.0 0.0 '0.0 0.0 



Mackerel '0.0 0.1 0.0 00 '0.0 0.0 0.0 0.0 



Other pelagics and other fish: 



Butterfish 3.6 18.1 3.9 5.4 5.0 4.2 11.0 3.7 



Spiny dogfish 47.8 3.1 4.9 0.0 0.0 0.0 '0.0 



Skates and rays 4.0 8 4 29.5 7 12.8 6.6 10.4 5.4 



Other 2 9.8 7.0 4.5 59 9.6 3.1 94 3.3 



Squid: 



Short-finned squid 0.3 0.2 0.1 0.4 0.2 0.3 '0.0 0.1 



Long-finned squid 10.6 9.3 9.2 48 2.5 12.6 11.2 11.1 



Total finfish and squid 218.8 73.7 72.7 31.3 36.0 35.1 47.5 27.5 



'Less than 0.05. 



2 Does not include data for tunas, sharks, swordfish, American eel, or white perch. 



