606 U. S. BUREAU OF FISHERIES 
stages to find the conditions that determine the number of individuals in any 
year class. In discussing the cod, Hjort stated as early as 1914 that the 
numerical value of a year class.apparently is determined at a very early stage 
and continues in approximately the same relation to that of the other year 
classes throughout the lifetime of the individual, and that such data as are 
available indicate that the most important determining stages are “the very 
earliest larve and young fry stages.” 
Therefore, if the numerical value of a year class is determined in the early 
stages, and the actual quantity of eggs produced is not necessarily the deter- 
mining factor, then we must look to the pelagic eggs and fry for an explanation. 
The cod-spawning areas along the New Hngland coast fall into two natural 
groups—the inshore grounds and the oftshore grounds. Because*of the lack of 
a suitable ship, the former were selected for investigation first, with the field 
work centered in and about Massachusetts Bay. As a result of the investiga-- 
tions by Doctor Bigelow, there was available considerable information on the 
seasons of spawhing, the seasonal variation in the plankton communities, and 
the general movements of the water in the @ulf of Maine. Drift-bottle experi- 
ments and observations on plankton distribution had established the existence 
of a definite southerly drift or set along the whole western margin of the gulf. 
This has long been known to the fishermen as the “so’west current.” Fish eggs 
in progressively later stages of development have also been found as one 
approaches Cape Ann from the east. Again, the catches extending over a long 
period of years have shown that the bay itself harbors one of the largest 
inshore breeding centers—the Plymouth grounds. 
The immediate problem involved a determination of the value of Massa 
chusetts Bay as a production center and also as a nursery for the large numbers. 
of eggs and larve that we had reason to believe were constantly being trans- 
ported in as contributions from the spawning grounds to the east. Here the 
young fry could find ample food and be protected from the storms and ocean 
waves until large enough to care for themselves. It has even been suggested 
that this limited area might form one of the most important sources of supply 
for codfish on the whole Atlantic coast. 
The work was to consist of an investigation of the Massachusetts and 
Ipswich Bay grounds, the conditions existing during the period of incubation of 
the eggs, the early life history, the food during this period, the enemies, and 
the distribution and migrations during the first year. 
In November, 1924, 2 visits were made to the Plymouth grounds, and between. 
December 3, 1924, and June 17, 1925, 14 cruises were made on the Fish Hawk, 
covering the area between Ipswich Bay and Provincetown. At 41 stations 
physical observations and net collections were made. 
Charts based on the distribution of eggs in various stages of development 
show clearly the spawning center and the drift of the eggs, the greater propor- 
tion of late stages being taken about the Provincetown region. Drift bottles 
also substantiated the current movement as indicated by the eggs. 
The results so far indicate that a very definite and constant counterclockwise 
drift carries all 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 the 14 cruises faiied to yield 
a single young cod. Drift bottles took the same general course as the eggs. 
those not fetching up on the inner arm of the bay dividing after passing beyond 
Provincetown. A part of the latter completed the circle and appeared on the 
Nova Scotia coast, or, if they turned south, passing into the region about Nan- 
tucket. One apparently drifted farther to the eastward and was carried in 
the Gulf Stream to the beach of Lands End, Cornwall, England, where it was 
recovered on June 15, 1926. 
Investigations carried on in Ipswich Bay, an important adjacent spawning 
ground to the north, yielded similar results, showing that here the eggs were 
carried out east or south, beyond Cape Ann, at even earlier stages than those 
of Massachusetts Bay. 
We must therefore conclude that local production in Massachusetts Bay is 
not sufficient to maintain the inshore stock, and were it not for constant immi- 
gration from the outer waters the supply would soon be exhausted. 
At the time, the lack of a suitable ship prevented an extension of the survey 
to the outer waters to determine the fate of the cod eggs after leaving the bay, 
the next logical step in the program. No doubt many of the eggs carried 
beyond the cape survive and perhaps help stock the outer banks, or else work 
ri 
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