FISHES OF THE GULF OF MAINE 



251 



trawled on the southern part of the Newfoundland 

 Bank in bottom water as cold as 33° F. (0.6° C), 

 while others reported from Bay Bulls, on the east 

 coast of Newfoundland and from Cut-throat 

 Harbor on the outer coast of Labrador (p. 254) 

 doubtless were in water equally cold. 



At the opposite extreme, it has been found that 

 only a few halibut are taken in the parts of the 

 North Sea where the bottom water is warmer than 

 46°^47° (go c ) ( none a t a ll where it is warmer 

 than 59° F. (15° C). And there is no reason to 

 suppose that halibut ever were plentiful anywhere 

 in the western side of the Atlantic in temperatures 

 much higher than about 46°-47°, for while the 

 bottom water warms locally to 50°-52° on Georges 

 Bank in summer, and to 52°-59° on Nantucket 

 Shoals, it was only during the winter and spring 

 that there ever was any regular fishing for halibut 

 on either of these grounds. 



On the other hand, the halibut that summer on 

 banks where the bottom chills below about 36° in 

 winter have been described repeatedly as with- 

 drawing to deeper (i. e., to warmer) water for the 

 coldest part of the year. Perhaps the best known 

 example is off west Greenland. Here the halibut work 

 in over the banks regularly in summer, from the 

 deeper waters of Davis Strait, as the temperature 

 rises, but work out again, and deeper, in autumn, 

 as the water cools again. 29 Thus it was only 

 deeper than 350 fathoms that long liners, fishing 

 there in 1926-28 30 found halibut in paying quan- 

 tities at the beginning of June, when the bottom 

 temperature on the banks was about 33°-37°. 

 But good catches were made as shoal as 200 

 fathoms by the middle of the month when the 

 temperature had risen to 35°-38°. And there was 

 good fishing as shoal as 70 fathoms by mid-July, 

 when the banks had warmed to 37°-39°, though 

 many of the halibut were in deeper water still. 



Halibut have been described as shifting ground 

 in the same way in the coastal belt of the Gulf of 

 Maine (p. 257) from season to season. On the 

 other hand, we suspect that halibut finding them- 

 selves in water shoaler than 30 fathoms or so in 

 the southernmost part of the range of the species, 

 on the American side, at the onset of summer may 



withdraw to slightly deeper water for the time 

 being, but definite information is lacking. 



The seasonal movement of halibut in onto the 

 Greenland Banks as early in the summer as 

 temperature allows seems to be in search of food, 

 as Jensen points out, for a much richer supply of 

 small fish is available to them on these shoaler 

 bottoms than deeper down the Davis Strait 

 slope, where they must depend chiefly on large 

 shrimps (p. 252). And we suspect that the food 

 supply is equally important in influencing the 

 seasonal movements of halibut in our Gulf. 31 



If the prevalent view is correct, the Atlantic 

 halibut resort to rather definite and circumscribed 

 ground to spawn, much as the Pacific halibut do. 



Halibut have also been credited with extensive 

 wanderings from bank to bank, for no evident 

 reason. And recent tagging experiments carried 

 out off Nova Scotia by the Fisheries Research 

 Board of Canada, 32 have proved that some of them 

 certainly do so, in American waters. Thus fish 

 that were marked on German and Browns Banks 

 have been recaught as far to the eastward as 

 Western Bank and in the general vicinity of 

 Sable Island, while one that was tagged at Anti- 

 costi was recaught at Seven Islands more than 100 

 miles to the westward. But most of the recaptures 

 were* made within a few miles of the places where 

 the fish had been tagged. And available evidence 

 as to halibut migrations in the Gulf of Maine and in 

 Nova Scotian waters is so contradictory, and 

 so greatly complicated by the local effects of hard 

 fishing, that it is not worth while to attempt any 

 further discussion here. 



Food. — The halibut is very voracious, preying 

 chiefly on other fishes, a long list of which have 

 been reported from their stomachs, including cod, 

 cusk, haddock, rosefish, sculpins, grenadiers, silver 

 hake, herring, launce on which they often gorge 

 in northern seas, 33 capelin, flounders of various 

 sorts (these seem to be their main dependence), 

 skates, wolffish, and mackerel. Halibut are also 

 known to eat crabs, lobsters, clams, and mussels; 



"Jensen (Meddelelser, Dansk Komm. Havunders., Ser. Flskert vol. T, 

 No. 7, 1925, pp. 17-18) seems to have been the first to bring this to scientific 

 attention. 



» Baldersheim, Rapp. Proc. Verb. Consell Internat. Explor. Mer, vol. 86, 

 1K29, pp. 25-28. 



« For a further discussion of the range and movements of the halibut m 

 relation to temperature, with references, see Thompson and VanCleve, Rept. 

 Internat. Fish. Comm. No. 9, 1936, pp. 22-38. 



« Martin and McCracken, Fish. Res. Board Canada, Progress Rept., 

 Atlantic Coast Station, No. 50, 1950, pp. 3-8. 



35 Capt. Baldersheim described halibut off west Greenland as sometimes 

 in schools, preying on launce (Rapp. Proc. Verb. Consell Internat. Explor. 

 Mir., vol. 5fi, 1929, p. 25). 



