466 



BtriiLETIN OF THE BUREAU OE EISHEBIES 



from April until June, and probably it lasts all summer in the Gulf of Maine, for 

 Mr. Schroeder reports a female on Platts Bank nearly ripe on July 23. In the 

 eastern Atlantic cusk spawn chiefly below 100 fathoms, judging from the distribution 

 of the eggs on the surface, but the chief production of eggs probably takes place 

 in water shallower than this in the Gulf of Maine, where most of the stock lives 

 in depths of less than 75 fathoms, and some must spawn close inshore, for we have 

 towed the larvae, only 6 to 13.8 mm. long, in Provincetown Harbor, off Cape Cod, 

 and near the Isles of Shoals,^^ but we have never detected cusk eggs in our tows 

 or seen perfectly ripe fish. The cusk is among the most prolific of fish, more than 

 2,000,000 eggs having been counted in a female of medium size. The egg is buoyant 

 like that of other gadoids, 1.29 to 1.51 mm. in diameter, with one oil globule of 



Fig. 233.— Larva (European). 12..5 millimeters. After Schmidt 



Fig. 234.— Fry (European), 42.5 millimeters. After Schmidt 

 CUSK (Brosmius brosme) 



0.23 to 0.3 mm., and it may be recognized by the brownish or pinkish color of the 

 latter and by the fact that the entire surface of the egg is finely pitted. 



The larvJB are about 4 mm. long at hatching, with the vent situated at the 

 base of the ventral finfold as in other gadoids, but they are separable from all 

 other gadoid larvae occurring in the Gulf of Maine by the pinkish oil globule at 

 the posterior end of the yolk. The latter is absorbed in about a week after hatching, 

 at a length of about 5 mm., and as the little cusk grows its ventral fins elongate 

 like those of young hake and young rockling and become heavily pigmented with 

 black. It is separable from both of these, however, by the fact that the ventral 

 rays are independent and by the presence of three black patches — one on top of 

 the head, a second over the gut, and a third at the tip of the tail — and two vertical 

 black bands which divide the trunk behind the head into three nearly equal sections. 



3« The station records are 10012, July 22, 1912, 1 specimen; 10343, July 20, 1916, 4 specimens; and 10344, July 22, 1916, 1 specimen. 



