FISHES OF THE GULF OF MAINE 97 



Moore was able to do it. Doctor Huntsman has informed us that on the Grand 

 Manan ground (where the temperature is kept practicallj^ uniform, verticalh', b}' 

 the violent tides) herring begin spawning when the water warms to about 46° to 

 47° F. The temperature there rises to only about 48° at 5 to 20 fathoms depth at 

 the height of the breeding season. Near Eastport, too, the average range of tem- 

 perature from the surface down to 5 fathoms is only about 44.6° to 52° for July, 

 August, and the first half of September, while a comparison of our temperature 

 records with the breeding season at different locaUties shows that in the northern part 

 of the Gulf practically all spawning is carried out in temperatures of 46° to 52°. In 

 the southern part of Massachusetts Bay and along the shores of Cape Cod, M'here 

 autumnal cooling of the surface waters is not as rapid as farther north, herring may 

 spawn in slightly warmer water, say up to 53° or 55°. The Gulf of Maine herring 

 spaA\'n in rather low salinities (such, indeed, characterize the coastal zone as a 

 whole as compared with the North and Norwegian Seas) , the most saline water in 

 which it is known to spa-\vn witliin our limits being not salter than 33 per mille, the 

 freshest probably about 31.9 per mille. They never spawn in brackish water ^ntllin 

 the limits of the Gulf, although known to do so in the almost fresh water of the 

 mouths of certain European rivers. 



LarvEe of the herring family are extremely slender and can easily be distin- 

 guished from all other young Gulf of Maine fish of similar form (e. g., launce, smelt, 

 or rock eel) by the location of the vent, which is so far back that it lies close to the 

 base of the tail, but it requires critical examination to distinguish our several 

 clupeoids from one another in their early stages. 



The sea herring is about 5 to 6 mm. long at hatching, with a small yolk sac that is 

 absorbed by the time a length of about 10 mm. is reached. The dorsal fin is formed 

 at 15 to 17 mm.; the anal at about 30 mm.; the ventrals are visible and tail well 

 forked at 20 to 35 mm.; and at about 40 mm. the little fish begins to look like a 

 herring. 



According to Huntsman's observations fry produced on the Grand Manan 

 spawning grounds in late summer and early autumn grow to a length of 17 to 20 

 mm. by the end of November or first of December, but there is every reason to 

 believe that the rate of growth slackens during the winter season, not only from 

 studies made elsewhere but because we have taken fry only 26 to 50 mm. long in 

 March and April (p. 100), while young herring 50 to 60 mm. long are abundant in 

 the St. Andrews region in June. These yearlings grow to about 90 to 125 mm. at 

 the end of their first year of life, fish of that size, presumably of the previous autumn 's 

 hatch, being abundant in the fall of the year in the Bay of Fundy. This works 

 out at an average growth of about 10 mm. per month for the warm half of the year, 

 which corresponds fairly closely with the rate at Woods Hole where, according 

 to Smith, young herring spawned in October and early November are 7 mm. long 

 in January, 25 to 32 mm. in May, 65 to 76 mm. in August, and 76 to 125 mm. in 

 their first autumn. In Norwegian waters, too, according to Hjort, the herring is 

 about 125 mm. long at the end of its first year of life,^^ and North Sea herring are 



88 Huntsman (1919) believed he could recognize spring as well as autumn-spawned herring fry in the Bay of Fundy, and 

 credits them with a length of about 90 mm. by the first and 150 mm. by the second winter. This, however, would seem to call 

 or confirmation, it being unlikely that herring now spawn in the Bay in spring (p. 95). 



