200 400 

 FREQUENCY 



2000 4000 

 FREQUENCY 



I MP I NGEMENT 



Fig. 7. Spring-summer and fall-winter seasonal length-frequency distribution by 20-mm size-classes of Atlantic tomcod 

 in trawl and MNPS Unit 2 impingement collections from 1976 through 1987. 



occurred in the number impinged since three-unit 

 operations. In trawls, over half of the tomcod 

 were caught at the nearshore stations (NR and 

 JC). Young-of-the-year dominated the trawl 

 catches in the spring and summer; adults were 

 caught mostly in the fall and winter (Fig. 7). 

 Trawl catches peaked from April through June, 

 except at NR, where most were caught during 

 their winter spawning season. 



The annual abundances of tomcod in trawls 

 were analyzed using the 5-mean as an index of 

 relative abundance; only data from catches at NR 

 and JC were sufficient to determine annual trends 

 (Table 13). Armual 5-mean catches were low and 

 during 2 report periods (1980-81 and 1985-86), 

 none were found at JC. The Atlantic tomcod is 

 a short-lived species and becomes sexually mature 

 during the fall of its first year (Klauda et al. 1987). 

 Marine fishes that are short-lived usually exhibit 

 large year-to-year variations in abundance because 

 population size is determined in a single spawning 



TABLE 13. The annual S-mean catch (CPUE) and 

 95% confidence interval of Atlantic lomcod caught by 

 trawls at stations JC and NR for each report period 

 (June-May). 



season and conditions during that season often 

 control spawning success. Tliis is evident in the 

 distribution of annual catches at JC. In 1980-81, 

 no tomcod were collected at this station, but 3 



274 



