266 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Our egg records, added to Huntsman's observa- 

 tions, show that the dab spawns all around the 

 Gulf of Maine, from Cape Cod on the west to 

 Cape Sable on the east, including the Bay of 

 Fundy, and from close inshore out to the 50-fathom 

 contour. Tt also spawns on Browns Bank (p. 265), 

 and, while we found no eggs on Georges Bank 

 either in February, March, April, or May, of 1920, 

 the fish is so common there and so stationary in 

 general that it is likely that we simply missed its 

 eggs, either by a failure to tow over the precise 

 spawning localities or by timing our visits between 

 the waves of production. Dabs also spawn 

 abundantly on Sable Island Bank (no doubt on 

 all the other Nova Scotian Banks); off Cape 

 Breton; in the shoaler parts of the Gulf of St. 

 Lawrence ; " throughout the general region of the 

 Grand Banks; off the east coast of Newfoundland; 

 along the outer coast of Labrador to Hamilton 

 Inlet at least; 1 and as far north along the west 

 coast of Greenland as the species is known to 

 exist, as is proven by the presence of its eggs in 

 the water there in quantities. 2 



Although the dab is rather a deep-water fish 

 compared to most of the other flatfishes that are 

 common in the Gulf of Maine, it is doubtful 

 whether it ever spawns at depths much greater 

 than 50 fathoms in the Gulf, for we have few 

 egg records from more than a mile or two outside 

 the 50-fathom curve, while these few have been 

 based on only one or two eggs each. And we have 

 trawled spawning females off Mount Desert, in 

 20 fathoms. This concentration of our egg catches 

 inside the 50-fathom contour implies that the 

 dabs that live deeper in our Gulf tend to work up 

 into shoaler grounds to spawn. Beyond this, 

 there is no reason to suppose that they gather in 

 any definite localities for the purpose. 



The temperatures and salinities in which the 

 eggs are produced can be stated rather definitely 

 for the Gulf of Maine because the dab lies close 

 to the bottom, if not actually on it. The earliest 

 spawning takes place at nearly the minimum 

 temperature for the year, averaging about 37° for 

 all the March and April stations where eggs were 



« Dannevig, Canadian Fisheries Expedition (1914-15) 1919, p. 18, flgs. 11, 

 12, and 13. 



' See Frost, Res. Bull. No. 4, Newfoundland Dept. Nat. Resources, 1938, 

 chart 2, for the regional and seasonal distribution of dab eggs in Newfoundland 

 and Labrador waters. 



» Jensen, Meddel. Dansk. Komm. Havundersdgelser, Ser. Fiskeri, vol. 7, 

 no. 7, 1925, p. 24. 



taken. And while the water warms to 41°-43° F. 

 by late May and early June at the depths known 

 to be inhabited by the ripe fish, we have not 

 found its eggs where the bottom temperature was 

 higher than about 40°. Thus the optimum for 

 breeding may be set at 37°-40° for the Gulf of 

 Maine as a whole. Dabs spawn freely in 31°-32° 

 off Cape Breton, and even in water as cold as 

 29.3°-32° in the Gulf of St. Lawrence, in New- 

 foundland waters and northward, as well as along 

 the West Greenland coast, proving that the lowest 

 polar temperatures are no bar to the ripening of 

 its sexual products. Neither does the distribution 

 of the bottom stages suggest that warmer water 

 is needed for the survival of the resultant larvae. 



In the Gulf of Maine the dab spawns in rela- 

 tively low salinities, the range there being only 

 from about 31.8 per mille to about 32.8 per mille 

 at the bottom at the stations where eggs were 

 taken in any number. But it does so in con- 

 siderably more saline waters in the other side of 

 the Atlantic, generally speaking. 



Although this flatfish spawns so generally 

 throughout the whole area that it inhabits, there 

 is evidence that different regions differ in their 

 suitability as nurseries, either for its eggs or for 

 the larvae. The southwestern part of the Gulf 

 of Maine must be favorable in this respect, for 

 we have taken larval dabs at 14 stations there, 

 most of these off the Massachusetts Bay region. 

 And they have also been taken at various localities 

 off the southeast coast of Nova Scotia; on the 

 Newfoundland Banks; in the Gulf of St. Lawrence; 

 along the east coast of Newfoundland; in the 

 Strait of Belle Isle; and northward for some dis- 

 tance along the outer coast of Labrador. But it 

 seems that reproduction does not succeed in the 

 Bay of Fundy, for neither the larvae nor the 

 young fry have ever been found there, although 

 dabs spawn there and the eggs develop, at least 

 partially. Failure to find any dab larvae off the 

 coast of Maine east of Penobscot Bay, though 

 eggs are produced there in abundance may be 

 due to the prevailing drift from northeast to 

 southwest along this part of the coast, because 

 of which buoyant eggs produced there are likely 

 to hatch a considerable distance to the west of 

 where they were spawned. The influence that 

 this drift may have on the distribution of larval 

 fish in the Gulf of Maine offers a fertile field for 

 future study. 



