280 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



almost any other bait for that matter, provided 

 the hook is small enough. 



Breeding habits. — The winter flounder is a winter 

 and early spring breeder, spawning from January 

 to May (inclusive) in New England. The season 

 is at its height during February and March south 

 of Cape Cod and in the Massachusetts Bay 

 region, 59 but it is somewhat later along the coast 

 of Maine; near Boothbay spawning commences 

 about March 1 and continues until about May 10 

 or 15 with the chief production of eggs usually 

 taking place from March 30 to April 20, according 

 to information supplied by Capt. E. E. Hahn, 

 former superintendent of the Boothbay hatchery. 

 Local differences of this sort in the spawning 

 season are probably due to variations in the tem- 

 perature of the water. After the severe winter 

 of 1922-23, for example, when the vernal warming 

 of the coastwise waters was slower than usual, 

 Captain Hahn wrote us from Boothbay that "the 

 fish were 10 to 15 days later in spawning than in 

 any previous year, the first eggs being taken on 

 March 24." On Georges Bank spawning fish 

 have been reported in April and into May. 



Thus spawning is well under way inshore while 

 the water is still near its coldest for the year; 

 i. e., about 32° to 35° F. in the Woods Hole region, 

 about 32° to 37° near Gloucester, and about 31° 

 to 35° near Boothbay, according to precise locality 

 and depth. And the major production of eggs 

 takes place there before the water has warmed 

 above about 38°, with about 40° to 42° as perhaps 

 the maximum for any extensive spawning in the 

 inner parts of our Gulf. The picture is not so 

 clear for Georges Bank, for we do not yet know 

 how early in the season flounders commence 

 spawning there. Those that spawn on the Bank 

 in April may do so in temperatures ranging from 

 about 38° to perhaps 42°, depending on the year, 

 on the precise date, and on the locality. 



Winter flounders spawn on sandy bottom, often 

 in water as shoal as 1 to 3 fathoms, but as deep as 

 25 to 40 fathoms on George Bank, and they do so 

 throughout the range of the fish, including the 

 Bay of Fundy, where Huntsman found its larvae 

 common near the mouths of estuaries. Most of 

 the eggs are produced in salinities from about 31 

 to 32.3 per mille in the inner parts of the Gulf, to 

 somewhere between 32.7 and 33 per mille on Nan- 



*• This species was propagated artificially at the Woods Hole, Gloucester, 

 and Boothbay hatcheries in large numbers. 



tucket Shoals and on Georges Bank. But those 

 that spawn in estuaries are known to do so in 

 brackish water, in salinities as low as 11.4 per 

 mille near Woods Hole, for instance. 



Individual females produce an average of about 

 500,000 eggs annually, and nearly 1,500,000 have 

 been taken from a large one of 3% pounds. They 

 spawn at night, at least those did that were kept 

 in the tanks at Woods Hole, where they seemed 

 indifferent to the electric lights overhead. And 

 Breder 60 describes the fish of both sexes as 

 swimming in a circle, about one foot in diameter, 

 clockwise so that the vent is outward, with the 

 eggs from the females flowing back along the upper 

 side of the anal fin and along the tail. After about 

 10 seconds of activity, they sink motionless to the 

 bottom. 



This species is peculiar among our local flatfishes 

 in that its eggs are not buoyant but sink to the 

 bottom, where they stick together in clusters, 

 usually so closely massed that the individual eggs 

 are forced into irregular outlines. They are 0.74 

 to 0.85 mm. in diameter, and newly shed eggs have 

 no oil globule, but some of them (if not all) develop 

 one as incubation proceeds. 61 Incubation occupies 

 15 to 18 days at a temperature of 37° to 38° F., 

 which is about what they encounter in nature. 

 The young larvae, which are 3 to 3.5 mm. long at 

 hatching, are marked by a broad vertical band of 

 pigment cells that subdivides the post anal part 

 of the body, a characteristic feature; and the end 

 of the gut also is heavily pigmented. In water of 

 about 39° the larva grows to 5 mm. in length, and 

 the yolk is absorbed (fig. 142) in 12 to 14 days. 

 The vertical fin rays begin to appear in 5 to 6 

 weeks after hatching, at a length of about 7 mm., 

 and the left eye has moved upward by then until 

 about half of it is visible above the dorsal outline 

 of the head, while the whole left eye shows from 

 the right side and the fins are fully formed in larvae 

 of 8 mm. Metamorphosis continues rapidly. 62 

 The left eye moves from this position to the 

 right side of the head; the pigment fades from the 

 blind side; the eyed side becomes uniformly pig- 

 mented; and the little fish now lies and swims 

 with the blind side down, its metamorphosis 

 complete when it is only 8 to 9 mm. long. 



» Copeia, No. 102, 1922, pp. 3-4. 



•' Breder, Bull. U. S. Bur. Fish., vol. 38, 1923, fig. 274g. 



•i Williams, Bull. Mus. Comp. Zool., vol. 40, 1902, No. 1, pp. 1-58, pis. 1-5. 

 See also Sullivan (Trans. Amer. Fish. Soc, vol. 44, 1914-15, pp. 125-136, 

 figs. 1-4) and Breder (Bull. U. S. Bur. Fish. vol. 38, 1923, p. 311). 



