I 8 8 Memoir Sears Foundation for Marine Research 



publication in the Bulletin of the Bingham Oceanographic Collection and hence were 

 not available to the authors of this volume, it was suggested that a summary of our 

 findings to date, in the form of an Addendum, would be useful. Although our studies 

 have been carried on intermittently since 1943 and intensively in 1950, it is apparent 

 that much of the life history of the Little Skate still rests on highly tentative ground, 

 and therefore some of the conclusions put forth below remain to be confirmed, modified, 

 or disproved by further observation and study. 



Our results have been derived chiefly from a study of collections obtained monthly, 

 or even more frequently, on a year-round basis from commercial draggers working 

 off the southern New England Coast, particularly in Block Island and Long Island 

 Sounds; in 1950 over 15,000 specimens were examined in detail. We have also been 

 fortunate in having large outdoor tanks and laboratory facilities available to us at the 

 U. S. Fish and Wildlife Service Station at Milford, Conn., through the generous 

 cooperation of Victor L. Loosanoff. 



In adult specimens, mating takes place throughout the year. This is clearly in- 

 dicated both by the sperm plugs in the uterus and by fresh wounds at the fundus of 

 the uterus, the latter being inflicted during copulation by the scimiter-shaped cartilage 

 or "sentinel" of the clasper. In our samples to date, not less than 30 "/q of the adult 

 females have shown wounds of this sort and a figure as high as 70 "/o has been recorded 

 in one sample; in general, then, at any time during the year a rough average of 50 % 

 of the adult females show fresh and often severe uterine lacerations — incontrovertible 

 evidence of recent mating. Since copulation is probably effected at times without so 

 wounding the female, it is a fair assumption that mating takes place frequently throughout 

 the year. Sperm are stored in large numbers in the convolutions of the shell gland, as 

 demonstrated by sectioning; we have no idea of the viability of sperm under these con- 

 ditions, but it would not seem to be a matter of importance in the reproduction of this 

 species in view of the frequency of mating. Indeed, perhaps there should be a revision 

 of the general conception that sperm are "stored" in the shell glands of other species 

 of Skates for the purpose of future fertilization; at least in erinacea, the whole female 

 genital tract apparently contains sperm so consistently that it is no wonder that some 

 find their way into the convolutions of the shell gland, a level which they must attain 

 to accomplish fertilization. 



Fertilization in adult females, as well as the production and laying of egg cases, 

 takes place the year around. However, there are two periods when egg-laying is at a 

 maximum, as judged by the percentage of pregnant fish in our samples. From late 

 October to early January this figure averages between 30 and 50 "/o and has run as 

 high as 59 % in one sample of Block Island Sound fish. Again in June and July, 25— 

 30 % of the adult females from these waters are pregnant. In other months of the year 

 less than 25 "/o are pregnant, a rough average for these "off" months for Block Island 

 Sound fish being 10 "/q, with the lowest level of production coming in August and 

 September. The same general pattern obtains in Long Island Sound samples, with 

 peaks of 10—15 "/o pregnancy in the November— January and June— July periods and 



