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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 1. — Size compositions of haddock catches from 

 Georges and Browns Banks 



' See text footnote 1. 



SIZES AT VARIOUS AGES 



Without sonic method of age determination, 

 we could only speculate about the ages of the fish 

 represented by the modes in these size distribu- 

 tions. Fortunately the age of haddock, at least 

 for the ages represented here, can be assessed 

 accurately by microscopic examination of impres- 

 sions of their scales. Figure 3 shows impressions 

 of scales of 1-, 2-, 3-, and 4-year-old haddock 

 collected on this cruise. 



Scale samples were taken from 1,285 haddock, 

 823 from Georges Bank and 462 from Browns 

 Bank. Tables 2 and 3 show the distribution of 

 these fish by size, and the number and percentage 

 of fish from each size group that wei-e assigned to 

 each age on the basisof scale examination. From 

 the percentages thus obtained, it was possible to 

 estimate how many fish in the total catch were 

 of each age. 



It was necessary to determine tlie number of 

 each age in the entire catch, rather than to use 

 only the age samples of tables 2 and 3, because 

 scales were taken from more large fish than from 

 small, in proportion to their abundance. This 

 was done because of the relative scarcity of 

 larger sizes and because of the greater number of 

 ages that make up the size groups of larger fish. 



The age composition of the total catch was ob- 

 tained by allotting the total catch of each size 

 group (table 1) to the various ages on the basis of 

 the percentages shown in tables 2 and 3. For 

 example, the Georges Bank age analysis showed 

 that, of all 18-centimeter fish for which age read- 

 ings were made, 100 percent were 1-year olds. 

 Accordingly, the total catch (511) of 18-centi- 

 meter haddock taken on Georges Bank were con- 

 sidered to be 1-year-old fish. Likewise, of all 

 36-centimeter fish for which the ages were read, 

 92.1 percent were 2-year-olds and 7.9 percent 

 were 3-voar-olds. Thus, of the 410 fish of 36 



Table 2. — Age composition of 823 Georges Bank haddock, by scale analysis 

 [In parentheses is the percentage that each age contributed to the total for each sl7.el 



1 See text footnote 1. 



