260 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



sand-, summer- and four-spotted flounders, pp. 

 290, 267, and 270) are left-handed, and the wide- 

 gaping jaws readily distinguish the American dab 

 from the various small-mouthed flounders. 



It is a comparatively broad (really deep) flounder 

 (about two and one-half times as long to base of 

 caudal fin as it is broad), more rounded in outline 

 than the halibut, with pointed nose, mouth gaping 

 back to abreast of the middle of the eyes, and with 

 one irregular row of sharp conical teeth in each 

 jaw. The free edges of the scales on the entire 

 eyed (upper) side of its body and of its head are 

 serrated with sharp teeth, which give the fish a 

 characteristic rough feeling when handled, but the 

 scales of the blind (lower) side are smooth-edged 

 except on the rear part of the body and along the 

 bases of the fins. The dorsal fin (76 to 96 rays) 

 originates in front of the middle of the left eye 

 and the anal fin (64 to 77. rays) arises slightly in 

 advance of the base of the pectorals. Both of 

 these long fins taper toward the head and toward 

 the tail, and there is a short, sharp, spine (the 

 prolongation of the post abdominal bone) pointing 

 forward close in front of the anal fin. The pec- 

 toral fin on the eyed side usually (not always) 

 has one or two more rays than its fellow fin on the 

 blind side, and is longer and more rounded, but 

 the two ventral fins, which are close in front of 

 the anal fin though entirely distinct from it, are 

 alike in size, shape, and location. The margin 

 of the caudal fin is always convex, either rounded 

 or with its middle rays so much the longest as to 

 form a blunt angle. The lateral line on the eyed 

 side is more clearly evident on the dab than on 

 most of our flatfishes, and it is straight from end to 

 end, except for a slight arch over the pectoral fin. 



Color. — Dabs run more uniform in color than 

 most of our smaller flatfish, ranging from reddish 

 to greyish brown (darker or paler) above and pure 

 or bluish white below. The tips of the rays of the 

 two long (dorsal and anal) fins are white. On one 

 specimen we saw the right edge of the eyed side 

 was white (like the blind side) from the gill opening 

 to the rearmost ray of the ventral fin but this is 

 unusual. Small fish are usually marked with 

 three to five dark spots along each edge of the 

 body; large ones are occasionally, though they are 

 plain colored as a rule. 



Size. — Adults measured by Welsh off Cape Ann 

 ran from about 12 inches to 24 inches, and few of 

 those that are caught in our Gulf are longer than 



2 feet. Nova Scotian fish measured by Hunts- 

 man 80 ran from 12 to 24 inches in length, while 

 fish caught in the colder waters off Newfoundland 

 averaged 18 inches. 81 The largest dab recorded 

 from American waters, taken near Sable Island, 

 May 1939, was 32K inches long and weighed 14 

 pounds. 82 The next largest, taken in 90 fathoms 

 on the northern edge of Georges Bank, November 

 1951, was 29 inches long. 83 



According to Huntsman, Nova Scotian fish 

 average about half a pound at 12 inches, 1% pounds 

 at 16 inches, 1% pounds at 18 inches, 2% pounds 

 at 20 inches, 4 pounds at 22 inches, and 6 pounds 

 at 24 inches. Massachusetts Bay fish are about 

 equally heavy at corresponding lengths. And a 

 16-inch fish from Georges Bank that we measured 

 weighed 1 pound 5 ounces; two fish of 18% inches 

 weighed 1 pound 13 ounces, and 2 pounds, respec- 

 tively ; one of 19K inches weighed 2 pounds 8 ounces, 

 and one of 29 inches weighed 9 pounds 6 ounces. 



This flatfish tends to differentiate into local 

 races in different seas. Thus the fin rays are more 

 numerous on the average in fish from high latitudes 

 than in those from low latitudes, while the body 

 is relatively wider in fish caught off Greenland 

 and off America than in those from Scandinavia 

 and from the North Sea. But these characters 

 vary so widely even in limited areas that the 

 Arctic-American and European species (plales- 

 soides and limandoides) have been united by 

 common consent long since, and we doubt whether 

 the corresponding "varieties" still recognized by 

 several recent authors will stand the test of time. 

 Huntsman's statement that the dorsal rays aver- 

 age more numerous in dabs from Bay of Islands, 

 Newfoundland, than in those caught on the New 

 Brunswick shore of the Gulf of St. Lawrence, with 

 Welsh's note of a variation of 7 in the number of 

 dorsal rays and of 6 in the anal rays in one lot of 

 fish caught off Gloucester, illustrates this vari- 

 ability. Notwithstanding the low latitude of the 

 locality of capture (about 42° 30' N.), this same 

 lot contained a specimen with the largest number 

 of fin rays yet reported (96 dorsal and 77 anal). 



All we dare say until many more specimens 

 are examined is that hereditary local races may 

 perhaps exist off different parts of the American 



» Bull. No. 1, Biol. Board Canada, 1918, p. 10. 



»' Frost, Res. Bull. 4, Newfoundland Dept. Nat. Resources, 1938, p. 8. 

 » McKenzie, Proc. Nova Scotian Inst. Sci., vol. 20, 1940, pp. 43-44. 

 » We measured this dab, taken by Capt. Arthur Nelson of the Eugene H. 

 who also caught several others, 27 to 28 inches long on this same trip. 



