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BULLETIN OF THE BUREAU OF FISHERIES 



In protected areas where no dominant drift occurs it is possible that young 

 pelagic forms oscillate back and forth on the rising and falling tides, later descending 

 to the bottom in approximately the same place from whence they originated. How- 

 ever, if we exclude such exceptional cases as inclosed bays and harbors, it is highly 

 improbable that a single one of the individuals seeking the bottom along our coast 

 succeeds in locating itself within miles of its point of origin. 



The importance of drifts in governing animal distribution is by no means con- 

 fined to invertebrate bottom forms. The relative importance of fish-spawning grounds 

 as production centers is to a large degree dependent upon ocean currents. When one 

 considers that for weeks and even months the helpless eggs and fry drift about at 

 the mercy of the winds and tides, battered by storms and surrounded by enemies, 

 it is not surprising that so small a percentage ever lives to reach maturity. Bigelow 

 (1926, p. 69), in discussing drifts, states: "Outside the outer headlands, however, the 

 journeyings of floating fish eggs are, generally speaking, so considerable that they are 

 often measured better by degrees of latitude and longitude than by miles." Off the 

 northern coast of Norway, Hjort (1914) found that young cod fry sometimes were car- 

 ried for hundreds of miles. He also found that the actual quantity of eggs produced 

 often is not in itself a factor sufficient to determine the numerical value of a year 

 class. A rich spawning year may yield a very disappointing year class, while a large 

 year class may have its origin in a very poor spawning year. This has been observed 

 repeatedly in Lofoten. 



However, it has also been found that the abundance of any age group probably 

 is determined by conditions in the very early stages. As early as 1914 Hjort 

 (1914, p. 204) stated: "The rich year classes thus appear to make their presence felt 

 when still quite young; in other words, the numerical value of a year class is appar- 

 ently determined at a very early stage and continues in approximately the same rela- 

 tion to that of other year classes throughout the lifetime of the individual." Again^ 

 in discussing which stage of development forms the most critical period, he added; 

 "Such data as are available, however, appear to indicate the very earliest larval and 

 young-fry stages as most important." 



In studying the distribution of fish eggs and larvae it is necessary to distinguish 

 between those species that collect on definite grounds to spawn and such pelagic 

 forms as the mackerel, which appear to spawn over extended areas, irrespective of 

 depth or bottom. The different starting points of the eggs must be taken into con- 

 sideration in interpreting movements in the latter species. The gadoids (cod, 

 haddock, and pollock), which have limited spawning areas, may be included as one 

 group, although they are not particularly favorable for a group study, having different 

 spawning areas as well as somewhat different breeding seasons. For that reason 

 only the cod (Gadus callarias) will be considered in the present paper. 



The breeding areas of the cod may be divided into two groups — the inshore 

 grounds and the offshore grounds. Among the latter may be mentioned Nantucket 

 Shoals, Georges Bank, Western Bank, and the Grand Bank. Ipswich Bay and the 

 spawning area off Plymouth are perhaps the most important of the inshore grounds 

 on the New England coast. 



The present paper is concerned with the results of an investigation to determine 

 the importance of Massachusetts Bay as a production center for cod and also its part 



