where the distance between anal and caudal fin 

 decreases. 



The length-weight relationship for this species 

 (Figure 2) was derived using data from 5 females 

 and 11 males. To determine the regression line, 

 the equation, log Y = 11.1204 + 2.99269 log X 

 was calculated using the nonlinear least squares 

 method of Pienaar and Thomson (1969). 



Clark and von Schmidt (1965) noted that adult 

 and juvenile males of several species of sharks 

 can be distinguished by the differences in the rel- 

 ative size and rigidity of the claspers. This 

 characteristic applies to A. superciliosus. Of the 

 males examined, the claspers of all but five indi- 

 viduals were large (10.8-13.0% of their FL), heav- 

 ily calcified, and quite obviously mature. Internal 

 examinations of the larger males revealed the 

 presence of sperm in the epididymis and sper- 



(0 



< 



o 



o 



UJ 



150 200 250 300 



FORK LENGTH IN CENTIMETERS 



Figure 2. — Length- weight relationship for Alopias 

 superciliosus. 



matophores in the lower ductus deferens. The 

 smallest male positively identified as mature was 

 307 cm TL. A smaller individual however of 289 

 cm TL had testes in a relatively advanced state of 

 development. Female A. superciliosus apparently 

 mature at a larger size than males. Of the 13 

 females examined (233-355 cm TL) only the 

 largest was mature. Ovaries of immature indi- 

 viduals were 10-13 cm long and 3-5 cm wide and 

 contained thousands of white opaque follicles 

 from less than 1 to 5 mm diameter. The oviducts 

 were firm, ribbonlike tubes 0.5 to 2.5 cm in di- 

 ameter The 355-cm female differed in that the 

 ovary was 30 cm long and 10 cm wide and con- 

 tained yellow ova up to 10 mm in diameter. Also 

 the oviducts in this individual were considerably 

 larger (10 cm in diameter) and more flaccid and 

 similar in appearance to the post gravid condition 

 of other species we have seen. We suggest A. 

 superciliosus males may mature at 290-300 cm 

 TL, but females are not mature until they reach 

 350 cm. 



Examination of the stomachs showed 17 

 (48.5%) were empty. Of the 18 that contained food 

 the most common items were squid (66%) and 

 scombrid remains (27%). One stomach contained 

 remains of 5 lancetfish; another, 30 small (5-10 

 cm) herringlike fishes; and a third had parts of a 

 small billfish, tentatively identified as an is- 

 tiophorid. The occurrence of two or more whole 

 longline baits in stomachs was not uncommon 

 and suggests they had been dislodged from hooks 

 elsewhere on the line. Alopias superciliosus may 

 utilize its tail to herd or stun its prey in the man- 

 ner described for A. uulpinus (Bigelow and 

 Schroeder 1948; Strasburg 1958). Several indi- 

 viduals including some of those lost at the rail 

 were foul hooked in the tail. 



Acknowledgments 



We are indebted to Frank Carey and John 

 Mason of the Woods Hole Oceanographic Institu- 

 tion who assisted during cruises aboard the RV 

 Gosnold and provided measurements on the 

 399-cm female; to Martin Bartlett for his assis- 

 tance aboard the Cap'n Bill III; to commercial 

 longliners Phil Rhule and Deba Larson and 

 James Beckett of the Canadian Fisheries Re- 

 search Board of Canada for their anecdotal in- 

 formation; and to Michael L. Dahlberg for help in 

 adapting the length-weight program for our 

 purposes. 



224 



