as well, to the role of the spiny dogfish in the com- 

 mercial fishery. 



Much of the information reported here is of 

 interest solely because it adds to man's fund of 

 knowledge about, the species; however, some of the 

 information has more concrete implications for 

 our commercial fishermen. This latter considera- 

 tion has been aptly summed up by Bigelow and 

 Schroeder (1948), who state: 



"From a practical aspect the spiny dog in the 

 "Western Atlantic is chiefly important because it 

 is undoubtedly more destructive to gear and inter- 

 feres more with fishing operations than does any 

 other fish — shark or teleost." 



DESCRIPTION 



The spiny dogfish is typically sharklike in ap- 

 pearance (fig. 1). In Western Atlantic waters it 



grows to a length of about 50-90 cm. and weighs 

 3.5-4.9 kg., with a maximum of about 100 cm. and 

 7.3-9.8 kg. The females are slightly larger than 

 the males (Bigelow and Schroeder, 1953). In the 

 Pacific Ocean, off the west coast of the United 

 States, the males reach a maximum of about 100 

 cm. and 3.9 kg., while the females reach a maxi- 

 mum of about 124 cm. and 9.8 kg. (Bonham et ah, 

 1949). 



The upper part of the fish is slate colored, some- 

 times tinged with brown, with irregular rows of 

 small white spots on each side. The white spots 

 are generally typical of younger fish and may be 

 lacking on older individuals. A distinguishing 

 feature of this shark is the presence of two sharp 

 spines, one anterior to each dorsal fin, the rear 

 spine longer than the front spine. Halstead 

 (1959) reports that a venom gland is located on 



r»2s 



Figure 1. — The spiny dogfish, Squahia acanthias. 



U.S. FISH AND WILDLIFE SERVICE 



