226 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



colorless oil globules 0.02 to 0.07 mm. in diameter, 

 scattered over the yolk, but most of these globules 

 unite shortly after fertilization into one large one 

 of 0.15 to 0.17 mm., which is sometimes single but 

 which usually has two or three tiny ones close 

 beside it. The embryo extends half way around 

 the yolk sphere within two days after fertilization 

 (at a temperature of 60° F.), and pigment has 

 appeared, one of the most characteristic features 

 of this species being the development of black 

 chromatophores not only on the embryo, but over 

 the yolk, and finally on the oil globule as well. 

 In late stages of incubation this feature, combined 

 with the small size of the egg and (usually) with 

 a multiple oil globule, distinguishes eggs of the 

 squirrel hake from all other buoyant fish eggs of 

 known parentage that have been found in the 

 Gulf, except for any rockling eggs that may have 

 pigmented oil globules (p. 236). There is also 

 some danger of confusing newly spawned eggs of 

 the squirrel hake with those of the butterfish (of 

 about the same diameter) for these sometimes have 

 two oil globules (p. 364). 



The newly hatched larvae have not been de- 

 scribed. Older fry (identity established either as 

 white hake or squirrel hake by comparison with 

 young fry that have been reared in the hatchery 

 by Louella E. Cable) already show the long, 

 slender ventral fins, the short first dorsal but long 

 second dorsal, and the tapering body form, char- 

 acteristic of the adults. These little hakes, green- 

 ish blue on the back, with silvery sides, are sep- 

 arable from rockling fry by their more slender 

 form, and by their scattered pigment. Older stages 

 are separable from rocklings by their two well 

 developed dorsal fins, while their silvery sides 

 mark them at a glance from the dull colored fry 

 of the cusk. 32 



Rate of growth. — The rate of growth during the 

 first few months cannot be stated until many 

 more young fry have been measured and identified 

 as the one species or as the other. It is probable 

 that two year classes are represented among the fry 

 that are caught along shore in summer. Some of 

 the smaller ones (2 to 3 inches long) may be from 

 the earliest spawned eggs of that same season, but 

 other squirrel hake of 2% to 4K inches (60-1 10 mm.) 



" Fry figured by A. Agasstz (Proc. Amer. Acad. Arts, Sci., N. Ser., vol. 9, 

 1882, pi. 7, fig. 6; pi. 8, figs. 1-3), as Motella argentala undoubtedly were 

 either white hake or squirrel hake. But the simple post anal pigment band, 

 short, stocky bodies, and fan-like ventrals of the younger stages pictured by 

 him under this same name (pi. 7, figs. 1-4) suggest that they were rockling. 



that were seined at Provincetown, on June 26, 

 1925, must have been about one year old, as they 

 were taken too early in the season to have been 

 the product of that year's spawning. And the 

 larger ones of 6 or 7 inches are yearlings. 



D 

 Figure 108. — Young stages of either white hake or squirrel 

 hake. A, larva, 2.2 mm.; B, larva, 6.2 mm.; C, larva, 

 9 mm.; D, young fry, 40 mm. silvery still, and living at 

 the surface of the water. Specimens collected off Woods 

 Hole. 



The growth of older squirrel hake in the Bay 

 of Fundy has been studied by Craigie; his 

 conclusions from scale studies, 33 combined with 

 the relative abundance of fish of different size 

 groups, being as follows. : 



Average length, 

 inches 



Age Male Female 



1 year-old 8 8 



2 years-old 13 14 



3 years-old 16 19 



The indicated rate of growth is so uniform 

 during the first three years of life as to suggest 

 that spawning (an event so exhausting that it 



" Contrib. Canadian Biol., (1914-1915) 1916, p. 87. Unfortunately, hake 

 scales do not show the yearly growth zones as clearly as cod and haddock 

 scales do. 



