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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



be even greater than its value for predictions. These separate correlations would 

 provide a basis for determining the size of spawning stock necessary to maintain an 

 undepleted fishery. Efficient utilization will be possible when a reliable estimate can 

 be made of tbe proper size of spawning reserve. Until then, there will always be 

 danger of reducing the annual take, on the one hand, by attempting to preserve more 

 spawners than needed, or, on the other hand, by catching more spawners than can 

 be spared from the stock needed for adequate reproduction. 



APPENDIX 



METHODS OF DETERMINING SIZE AT MATURITY 



Samples of fish were taken at various times at Woods Hole, Provincetown, and 

 Sagamore, Mass., during the period June 24 to July 21, 1925. The fish were measured 

 to the nearest half centimeter on a straight line from tip of snout to the extremity of 

 the midcaudal rays. Gonads of the males were graded by eye as small translucent, 

 small opaque gray, enlarged white, running milt, and spent. The last three grades 

 were classified as mature. Gonads of females were graded by eye as small translucent, 

 small granular, enlarged granular, translucent spots, running ripe, and spent. The 

 last three grades were classified as mature. The results are summarized in table 13. 



Table 13. — Size of mackerel at maturity as indicated by 1,116 individuals taken by traps in the 

 vicinity of Woods Hole, Mass., and in Massachusetts Bay during the period, June £4 to July SI, 

 1925 



