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BULLETIN OF THE BUREAU OP FISHERIES 



as Massachusetts Bay. If such a drift should bring larvae to a depleted area, restora- 

 tion of the cod stock there might be rapid. For example, although the adult cod 

 from the region of Nantucket Shoals apparently do not migrate north of Cape Cod, 

 many of them may have originated from eggs transported from the Gulf of Maine. 

 Therefore, if Prince (1909) were correct in his view that the restoration would be a 

 matter of a long time, it would be necessary to assume that of the millions of fry that 

 Hjort (1914) found to be carried sometimes for hundreds of miles, being sown over 

 the coastal banks, few, if any, survive, and such a condition is inconceivable. 



SUMMARY 



1. Cod spawn at a wide range of temperature in Massachusetts Bay. Consid- 

 erable spawning was taking place on November 12, 1924, at a time when the surface 

 temperature had fallen to only 10.1° C. At Plymouth the height of production 

 continued through the coldest season (0° C. or even lower in places). In Norway 

 it has been found that spawning cod are limited strictly to a water layer between 

 4° C. and 6° C. 6 Spawning in the bay continued throughout April, but apparently 

 had ceased by May 20, 1925. These grounds could be established easily as the 

 production center for locally spawned eggs throughout the season. 



2. The results indicate clearly that a very definite and constant counterclock- 

 wise drift carries cod eggs spawned in Massachusetts Bay out before they hatch. 

 Throughout the breeding season eggs were found in abundance, particularly about 

 the Plymouth grounds, but the collections of 14 cruises failed to yield a single young 

 cod. 



Some of the drift bottles set out to indicate the rate and direction of the drift 

 fetched up on the inner arm of Cape Cod. Those escaping Massachusetts Bay 

 divided into two branches, one of which completed the circle about the margin of 

 the Gulf of Maine and appeared on the Nova Scotia coast. Those turning south 

 passed into the region about Nantucket. One apparently drifted farther to the 

 eastward and was carried in the Gulf Stream to Lands End, Cornwall, England, 

 where it was recovered more than a year later. 



Investigations carried on in Ipswich Bay (an important adjacent spawning 

 ground to the north) yielded similar results, showing that here the eggs are carried 

 east or south beyond Cape Ann at even earlier stages than in Massachusetts Bay. 



There is evidence that some of the eggs entering Massachusetts Bay from + he 

 east in the late spring hatch before leaving the bay, but this is of minor importance, 

 for the fry drift for two to two and one-half months, and the same current that car- 

 ries them in from the east transports them out again on the south. They are merely 

 transients. 



We must therefore conclude that local production in Massachusetts Bay does 

 not maintain the inshore stock, and were it not for constant immigration from the 

 outer waters the supply would be exhausted. As a nursery, its value can be no 

 greater than that of any other equal sector of the coastal belt, but as a source of 

 supply for offshore banks it may prove of significance. This will depend upon the 

 ultimate destination of the eggs passing beyond Cape Cod. It is probable that 

 Nantucket Shoals, Georges Banks, and the grounds in the Gulf of Maine may all 

 benefit by this dispersal. 



• Proces-Verbaux, Conseil Permanent International pour 1' Exploration de la Mer, Vol. XXXVIII, September, 1926, p. 82. 



