266 



BULLETIN OF THE BUREAU OF FISHERIES 



distribution of the pelagic eggs. The slight variation in the depth of the vertical 

 hauls (a matter of a few meters at most) becomes insignificant when included with 

 a 20-minute horizontal haul. 



In examining the eggs the following stages were distinguished and recorded: 

 Early cleavage, late cleavage, early embryo, and late embryo. Later, in preparing 

 the charts, only the early-cleavage and the late-embryo records were used. 1 This 

 extreme contrast facilitated the plotting and also simplified the results. 



In making composite charts to show the general movements of the eggs the first 

 eight cruises and the last four have been combined in two groups. This was done in 

 order that the first group would not be complicated by the great influx of haddock 

 eggs from the northeast in the late spring. 



SUMMARY OF OBSERVATIONS 



GENERAL CONDITIONS 



The problem, as already stated, involved a determination of the value of Massa- 

 chusetts Bay as a production center for cod and also as a nursery for the large number 

 of eggs and larvae that we had reason to believe were being transported in continually 

 as contributions from the spawning grounds to the north and east. It is known that 

 of the millions of eggs liberated on cod banks, probably few escape fertilization, and 

 also that under normal conditions these eggs tend to float near the surface. (Prince, 

 1909.) Ample stations were selected to allow for a determination of the distribution 

 of eggs and larvae within the bay at any one time. By preparing charts on the 

 distribution of eggs in various stages of development it was hoped that the directions 

 and rate of dispersal would be shown. 



THE ABSENCE OF FEY 



On the 14 trips hundreds of hauls were made and thousands of eggs were obtained, 

 but not one larval cod appeared. It was evident that the eggs were disappearing 

 before they hatched. To ascertain whether they were concentrated at some par- 

 ticular depth, hauls were made at all levels but without success. No cod fry appeared 

 although larval pollock and later larval haddock were fairly numerous sometimes. 



DEFINITE DRIFT OF EGGS 



Charts based on the distribution of eggs almost without exception indicated a 

 concentration of early stages over the spawning grounds and of later stages along the 

 lower arm of Massachusetts Bay, and particularly in the outer parts. (See figs. 6 and 

 7.) Thus, on the first 8 cruises, 88.7 per cent of the eggs taken at station 11 (in the 

 heart of the Plymouth grounds) were in early-cleavage stages and only 11.3 per cent 

 contained embryos. These figures become even more significant when divided into 

 four groups, 30.8 per cent of the eggs being in early cleavage, 57.9 per cent in late 

 cleavage, 7.9 per cent containing early embryos, and 3.4 per cent late embryos. Con- 

 trasted with this, station 3 (at the outer entrance to the bay) yielded not one egg in 

 early cleavage, but 40 per cent were late embryos. 



> These two stages in the present paper are distinguished as follows: Early cleavage extends from fertilization to a point where 

 the exact cleavage stage can not be distinguished easily (32 to 64 cell stage). In late embryos the chromatophores are arranged in 

 groups and give the characteristic banded appearance. 



