140 Commercial Shark Fishing in the Caribbean Area 



Figure 52 



Family Squalidae, Spiny Dog Fishes. Only five gill openings, 

 the lower ends of all of them in front of the origin of the pectorals ; 

 two dorsal fins but no anal fin; with spiracles; the trunk cylindrical 

 of the ordinary "shark" form; the front margins of the pectoral 

 fins do not extend forward past the gill openings ; each dorsal 

 fin has a spine, long in some, but so short in others that it is 

 apt to be overlooked. 



Genus Squalus, Spiny Dog Fishes. The dorsal spines are at the 

 points of origin of the fins and lie along the front margins of the 

 latter; the teeth have only one cusp and the uppers and lowers 

 are alike. 



Figure 52. Squalus acanthias, Common Spiny Dog Fish. 



Description: This Dog Fish closely resembles Squalus cubensis 

 (Figure 53), but is easily distinguished from the latter by the 

 facts that the inner corner of its pectoral is rounded and the inner 

 margin only weakly concave, also that the point of origin of its 

 first dorsal (or first dorsal spine) is over or behind the inner 

 corner of the pectoral when the latter is laid back and that its 

 sides are usually spotted with white. 



Color: Slate colored above, sometimes tinged with brown; the 

 sides irregularly marked with small white spots, (except in very 

 large specimens on which they may be lacking) ; grayish or pure 

 white below. 



Size: Born at a length of 9 to 13 inches; males mature at 24 to 32 

 inches, females at 28 to 40 inches; adults (both sexes included) 

 average from 2 feet to 3-1/2 feet long and 7 to 10 pounds in weight ; 

 a few grow to 4 feet, perhaps longer. 



Habits: Chiefly in continental as contrasted with oceanic 

 waters, anywhere between the surface and the bottom down to a 

 depth of 90 to 100 fathoms; often in large schools and extremely 

 abundant locally. In the northern part of their range they are 

 regular migrants with the seasons northward and inshore in spring, 

 southward and offshore in autumn. They feed on fish of all avail- 

 able kinds, not only those smaller than themselves but even larger. 

 When abundant they are a great nuisance to fishermen for when 

 they are taken out of water they use their spines for defense, and 

 it is probable that these are slightly poisonous. The young are 

 born chiefly from late autumn through the winter. 



Range: Both sides of the north Atlantic, chiefly in temperate 

 and subarctic latitudes; also both sides of the northern North 

 Pacific; with close allies in corresponding latitudes in the south- 

 ern hemisphere. This is by far the most plentiful of sharks along 

 the coasts of the northeastern United States and of Canada. It 

 is also certain that a few occur as far south as Cuba. It is prob- 

 able, however, that published references to it there and around 

 Trinidad were actually based on Squalus cubensis. 



