FISHES OF THE GULP OF MAINE 285 



Captures of eggs off Libbey Island prove that dinners spawn eastward along 

 the Maine coast nearly to the mouth of the Bay of Fundy, though in diminishing 

 number beyond Penobscot Bay. It is doubtful, however, whether eggs produced 

 along the northern coast of the Gulf east of Mount Desert yield more than a very 

 small proportion of fry, nor do cunners breed successfully in the cold water of the 

 Bay of Fundy, where no small ones are ever seen, though some few eggs are spawned 

 there. However, the Bay of Fundy is simply a gap in the breeding range, for St. 

 Mary Bay is a productive nursery, while both eggs and larvae were taken at 

 various localities along the outer coast of Nova Scotia and in the southern part of 

 the Gulf of St. Lawrence by the Canadian Fisheries Expedition during the simamer 

 of 1915. 



The eggs are buoyant, transparent, only 0.75 to 0.85 mm. in diameter, and 

 without an oil globule. In temperatures of 70° to 72° incubation occupies about 

 40 hours. In the cooler waters of the GuK of Maine (55° to 65°) probably about 

 3 days are required for hatching. At hatching the larvae are about 2 to 2.2 mm. 

 long, with a large yolk sac that is resorbed after about 3 days, by which time the 

 larva has grown to about 2.8 mm. and its mouth is formed. The caudal fin rays 

 are first visible at about 4.2 mm. The vertical fin rays and spines are well devel- 

 oped, the ventrals have appeared (but are still very small), and the head and 

 caudal fin have begun to assume their adult outline at about 8 mm., while at 15 

 mm. the young cunner is of practically adult form. In newly hatched larvae the 

 pigment cells are scattered uniformly over head and trunk, but by the 3-mm. stage 

 they gather into a pair of black spots, dorsal and ventral, about half-way between 

 the vent and the base of the caudal rays, which are very characteristic of the species 

 and persist to about the 10 to 20 mm. stage. By the time the fry have grown to 

 about 25 mm. they are as variable in color as their parents (it is on record that 

 Louis Agassiz had sixty colored sketches of small cunners 3 to 4 inches long, of 

 different hues, prepared at Nahant during a single summer) ." 



Larval cunners and small specimens generally are even more closely confined 

 to the coast line than are cunner eggs — so closely, indeed, that it is impossible to 

 represent their localities on a general chart of the Gulf, all the catches of 100 or 

 more having been made either in harbors or at most not a couple of miles from 

 land. The precise records have been published elsewhere." 



Bate of growth. — The growth of the cunner has not been traced in detail, but 

 since fry of 1 to 1.2 inches have often been taken in August and young fish up to 2 

 inches in September in southern New England, we may assume that in the Gulf of 

 Maine the earliest hatched fry grow to 23^ or 33^ inches by the end of the autumn. 

 The 4 to 6 inch fish, so plentiful, are then in their second summer. Cunners mature 

 as young as this, for ripe fish no longer than 3 inches have been taken. 



" The embryology and larval development of the cunner have been described by Agassiz (1882, p. 290, pis. 13 to 15), Agassiz 

 and Whitman (1885, p. 18, pis. 7-19, and Memoirs, Museum of Comparative Zoology at Harvard College, vol. 40, No. 9, 1915, 

 pis. 32-39), and Kuntz and Radcliae (1918, p. 99, flgs. 18-29). 



« Bulletin, Museum of Comparative Zoology at Harvard College, Vol. LVIII, No. 2, 1911, p. 108, and Vol. LXI, No. 8, 1917, 

 p. 271. 



