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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



the considerable thickness of its body. But it is 

 distinguishable from the winter flounder by the 

 fact that the skin of its head between the eyes is 

 smooth and scaleless. Females are more easily 

 recognized than males, their bodies also being 

 smooth to the touch on both sides; males are 

 nearly as rough skinned on the eyed side (except 

 between the eyes) as the winter flounder, but they 

 have much longer pectoral fins than the latter. 

 Both sexes have fewer anal fin rays (only 35 to 40) 

 and dorsal fin rays (about 56), too, while the 

 caudal fin of the smooth flounder is narrower and 

 more rounded than that of the winter flounder. 



The smooth flounder can always be separated 

 from the yellowtail by the facts that its very 

 prominent lateral line is straight, not arched, 

 that the dorsal (left) profile of its head is straight, 

 not concave; and that it has fewer fin rays. 

 It has little more than half as many dorsal and 

 anal rays as the witch, and its long fins are 

 highest midway of the body and tapering toward 

 the head and tail, whereas they are nearly uni- 

 form in height from end to end in the witch. 

 It lacks the mucous pits that are so characteristic 

 of the blind side of the head of the latter, a 

 convenient field mark for separating these two 

 species. 



The smooth flounder is peculiar among our 

 local flatfishes for its sexual dimorphism. Besides 

 the difference in the scales of the two sexes noted 

 above, the pectorals on the eyed side are longer 

 (about four-fifths as long as the head) and more 

 pointed on the males than they are on the females. 



Color. — The smoothback varies from grayish 

 to dark muddy or slaty brown above, or to al- 

 most black, either uniform or variously mottled 

 with a darker shade of the same tint; the dorsal, 

 anal, and caudal fins are of the general ground 

 color. These fins were mottled darker or paler, 

 in specimens we have examined, but Storer de- 

 scribed them as black spotted. The blind side 

 is white. 



Size. — This is the smallest flatfish that is com- 

 mon in the Gulf of Maine, for it grows to a max- 

 imum length of only about a foot, and to a weight 

 of about a pound and a half. 



Habits. — This flatfish is confined to the close 

 vicinity of the coast throughout its geographic 

 range, occurring chiefly in estuaries or river 

 mouths, and in sheltered bays and harbors; mostly 

 on soft mud bottom. Correspondingly, it is found 



from tide line down to a maximum depth of per- 

 haps 15 fathoms, with 2 to 5 fathoms as its zone of 

 greatest abundance in our Gulf. 



It prefers soft bottom to hard; so much so that 

 a seine haul on soft mud yielded 23 smooth 

 flounders to 4 winter flounders in St. Mary Bay, 

 whereas another haul, only 100 yards or so dis- 

 tant, but on harder bottom, brought in only 3 

 smooth flounders to 189 winter flounders, as 

 we learn from Dr. Huntsman's notes. 



The shoal water habit of the smooth flounder 

 exposes it to temperatures close to the freezing 

 point of salt water in winter, and as high as 60° 

 in summer, and perhaps higher temperatures 

 still in some places. Little more is known 

 of its life. But its small mouth suggests a diet 

 similar to that of the winter flounder, and Kendall 

 found that yoimg fry 3 to 4 inches long from 

 Casco Bay has been feeding chiefly on small 

 crabs, shrimps, unidentified crustaceans, and 

 polychaete worms. 



Winter is its breeding season, females nearly 

 ripe having been taken in Salem Harbor in 

 December and spent fish at Bucksport, Maine, 

 the first week in March, which corroborates 

 fishermen's reports of more than half a century 

 ago that it comes into Salem Harbor to breed 

 at about Christmas time. It is not known 

 whether the eggs sink or are buoyant, nor have 

 its larvae been seen. 



General range. — The smooth flounder is Arctic- 

 boreal. It is definitely recorded from as far 

 north as Ungava Bay, hence no doubt occurs 

 along the Atlantic coast of Labrador; it is de- 

 scribed as the most plentiful flatfish along the 

 coasts of the Strait of Belle Isle at all seasons; 76 

 its young are common in Pistolet Bay on the New- 

 foundland side of the Strait in shallow sun- 

 warmed pools, 77 and there are two specimens 

 from the north shore of the Gulf of St. Lawrence 

 in the Museum of Comparative Zoology (col- 

 lected mary years ago, labeled "Labrador"). 



Evidently it is widespread on the southern side 

 of the Gulf of St. Lawrence, for it is the next most 

 plentiful flatfish after the winter flounder on the 

 Cape Breton shore and at the Magdalens, accord- 

 ing to Cox; 78 it is reported from Prince Edward 



'• Jeffers (Contrib. Canadian Biol., N. Ser., vol. 7, No. 16 (Ser. A, No. 13 

 1922, p. 210). There are specimens from St. Anthonys, northern Newfound- 

 land, in the Museum of Comparative Zoology. 



" Eept. Newfoundland Fishery Res. Comm., vol. 1, No. 4. 1932, p. 110. 



'• Contrib. Canadian Biol. (1918-1920). 1921 p. 113. 



