192 Memoir Sears Foundation for Marine Research 



we find that in Long Island Sound the majority of Skates range from 39-44 cm, with 

 a few up to 47 cm in length. In the Block Island Sound samples the majority of fish 

 fall between 42 and 48 cm with a few from 49—54 cm. In short, on an average the 

 Long Island Sound erinacea of both sexes are adolescent at a lesser length and mature 

 at a lesser length than their Block Island Sound counterparts; further, the peaks of 

 length-frequency curves of fish from Long Island Sound are consistently a good 3 cm 

 less than the peaks of those from Block Island Sound samples, and the Long Island 

 Sound fish never attain the uppermost size limit of the largest ones from Block Island 

 Sound, i. e., up to 48—54 cm. Considering this, and the previously mentioned fact 

 that Long Island Sound erinacea are much less prolific, plus the fact that there is ap- 

 parently no substantial intermingling between the two areas, it is rather clearly indicated 

 that these are two essentially separate populations. The one from Long Island Sound 

 we think of as poor, slow-growing, and relatively unproductive; the other, from Block 

 Island Sound and seaward, we think of as the more normal, healthy, faster-growing, 

 and comparatively productive population. Further evidence to support this contention 

 is found in the fact that at all times of year comparable trawl hauls in Block Island and 

 Long Island Sounds yield many more fish in the former area than in the latter; the 

 former appears to be a flourishing population, the latter a sparse and rather unsuccessful 

 one. Comparing the Block Island and Long Island Sound populations further, the sex 

 ratios show peculiar differences. In Block Island Sound, males dominated the adult 

 population (60— 80 "/o) throughout 1950 (except for March-April), while in Long 

 Island Sound, females dominated the adult population (70 "/q) throughout 1950 (except 

 in March— April). In both areas the females dominated the immature population (at 

 least 70 "/o) with few exceptions. Morphometric comparisons between the two popul- 

 ations will almost certainly show significant differences, and apart from occasional 

 strays and a minor amount of intermingling at the adjacent boundaries of the two areas, 

 the Long Island and Block Island Sound erinacea may well be considered two separate 

 races. 



In this connection, if this species should be fished hard commercially for fish 

 meal or other purposes (Vitamin A is low, approximately 100 units per gram of liver 

 oil), we have every reason to believe that the catch-per-unit-of-effort would decline 

 rapidly; in short, the Little Skate would not be capable of yielding a steady supply 

 over long periods. Leaving the Long Island Sound population out of consideration 

 because of its paucity, the Block Island Sound fish command our attention because 

 they are probably more representative of this species over its whole range. From what 

 we have indicated previously of growth rates, sharp mortality above 46 cm, age at 

 maturity, percentage of fertilization, survival to hatching, etc., it would appear that this 

 species has no great capacity to increase the present size of the total population ; it 

 is clearly not a fish which is subject to marked fluctuations in abundance from natural 

 causes. Correspondingly, a reduction in the numbers of sexually mature fish by in- 

 creased fishing effort would shortly lead to a reduction in the number of young that 

 would be added to the stock each year. If only one out of every four to ten egg cases 



