FISHES OF THE GULF OF MAINE 395 



marked with two black and yellow transverse bars. In larvae of 6 to 7 mrn. the 

 yolk has been absorbed and the caudal fin rays have appeared; the dorsal and anal 

 fins assume their definite outlines by the time the little fish is 10 to 11 mm. long; 

 and fry of 20 to 25 mm. begin to resemble their parents. 61 The position of the vent 

 together with the transverse pigment bars are diagnostic for the youngest larvse, 

 while the large head, slender trunk, and, in older larvae, the outlines of the dorsal 

 fins are diagnostic, of the later larval stages. 



The locations at which silver hake eggs and larvse have been taken (fig. 195) 

 exhibit one very striking phenomenon — total failure to find larvae at the more north- 

 ern and eastern stations or eggs at the more southern and western stations. Dan- 

 nevig 61 ' has already called attention to the absence of larvae contrasted with the abun- 

 dance of eggs in Nova Scotian waters, suggesting that the disparity may mirror the 

 percentage of eggs that survive and hatch there. Such calculations, it is true, must 

 rest on very slender bases until more is known of the biology of this fish, nor does the 

 presence of larvae contrasted with apparent absence of eggs west of Cape Cod in sum- 

 mer prove that the former pass the cape only as immigrants from east and north, 

 for silver hake may spawn there so early in the season that their eggs have escaped 

 the summer tow nettings. We have towed so often along the coast of Maine in 

 August, September, and October, however — that is, just the season when the 

 larvae spawned from June to August might have been expected — that failure to find 

 larvae east of Cape Elizabeth in the Gulf of Maine, contrasted with their frequent 

 capture and local abundance (p. 394) in the Massachusetts Bay region, seems suffi- 

 cient evidence that they are actually limited in their occurrence to the southwestern 

 part of the Gulf, in which young silver hake parallel the young cod, haddock, and 

 flatfish. This phenomenon, with other simdar facts of distribution suggests a 

 peripheral drift around the shores of the Gulf from northeast to southwest, in 

 which first the eggs and then the resultant larvne take part. So well, indeed, has 

 this type of circulation been established for the Gulf by hydrographic evidence that 

 some such involuntary migration is inevitable, not only for buoyant fish eggs and 

 larvae produced near the coast line, but likewise for the whole category of pelagic 

 invertebrates and plants. 



Presumably the young silver hake takes to the bottom during its first autumn 

 when about 1 to 1}4 inches long, as does its European relative. Indeed, such small 

 fry have been trawled in deep water off southern New England (p. 389). 



The rate of growth of the American silver hake is yet to be studied, nor can 

 it be deduced from that of the European species, for the latter grows to a con- 

 siderably greater length, averaging as much as 30 inches at 8 years in the extreme 

 north of its range (Iceland) and considerably larger in the south (Gulf of Gascony 

 and off Morocco 62 ). It is fair to assume, however, that the growth of the American 

 fish varies similarly with latitude (that is, is most rapid in high temperatures) and 



•' Kuntz and RadcliHe (1918, p. 109) describe the early stages. 



•'<• Canadian Fisheries Expedition, 1914-15 (1919). 



« Belloc Notes et Memoires No. 21, Office Scientiflque et Technique des Pecbes Maritimes, Janvier 1923, 32 pp. Paris. 



