274 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



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Figure 5. — Areas of shallow, medium, and deep water in the subareas of Area XXII South, and the proportion con- 

 sidered productive (using the contoiir of 50 days of fishing per unit area as a criterion). Left-hand side shows percent 

 of productive area in each subarea. Right-hand side shows productive (black) and nonproductive (stippled) areas 

 in each subarea. 



The productivity of the shallow zone is in reality 

 somewhat higher than is indicated by the data, 

 because these portions of the bank are often 

 avoided in stormy weather and they are not 

 heavily populated with cod or haddock except at 

 certain seasons. However, this zone contains an 

 abundance of blackbacks, lemon sole, and yellow- 

 tail flounders. 



DISTRIBUTION OF DIFFERENT SPECIES 

 ACCORDING TO DEPTH ZONES 



Before intelligent measures can be formulated 

 in a fishery-management program, it is highly 

 desirable, and usually necessary, to be able to esti- 

 mate the abundance of the population. For a 

 species that forms the principal object of a fishery, 

 such as haddock, the changes in the catch per day 



