78 BULLETIN OF THE BUREAU OF FISHERIES 



certainly one of the most important off the American coast, may even contribute 

 to the fish stock of the Grand Banks. 



Haddock or any other bouyant eggs spawned on Browns Bank, or German 

 Bank to the north of it, would probably tend either northward into the gulf or west- 

 ward toward Georges Bank, depending upon the precise state of the Nova Scotian 

 current at the time; and it is probable that this was the source of the cod-haddock 

 eggs towed over the eastern side of the basin on May 6, 1915 (station 10270), and 

 on April 17, 1920 (station 20112). Larva? hatched on Browns and German Banks 

 might be expected to follow the same route during the spring, if living at about 40 

 to 50 meters, which it is probable that most of them do. Eggs spawned on Browns 

 and German Banks after the rush of water past Cape Sable has slackened, would 

 be more apt to be drifted northward toward the Bay of Fundy, but this would apply 

 mostly after the spawning season of the haddock had passed. 



It is obvious that if practically no production of the species of gadoids and 

 flatfishes that lay buoyant eggs takes place in the Bay of Fundy, and if most of those 

 produced along the northern side of the gulf drift away to the southwestward, as 

 the evidence marshalled above seems to prove, there must be as regular an immigra- 

 tion of the older fry back again to maintain the stocks of adult fish. However, this 

 subject does not immediately concern the plankton. 



It is interesting to compare the chart of gadoid and flatfish fry (fig. 35) with 

 the corresponding chart for the rosefish (Sebastes), a viviparous species (Bigelow 

 and Welsh, 1925, fig. 120), as an illustration of the degree to which the dispersal 

 of larval fishes depends on the precise locality where they are produced. In the case 

 of the former this happens chiefly inside the 100-meter contour, with the result just 

 described. No doubt, when young rosefish are born in that belt and chance to rise 

 near the surface they follow the same route, journeying with the dominant set. But 

 rosefish also produce their young generally over at least the northern half of the 

 deep basin of the gulf, where the dominant anticlockwise eddy is felt less. It is 

 also probable that in most cases the young Sebastes, like their parents, live 

 rather below the level of the most active currents, hence are less apt to be caught 

 up by them. Further (though less important in its effect than is the location of the 

 breeding grounds in relation to the circulation of the gulf) , Sebastes is so compara- 

 tively large and strong at birth that its involuntary migrations cover a shorter period 

 than those of most of the fishes that lay floating eggs, and consequently its larvae 

 are to be found widespread, except close to land, and not concentrated in any one 

 part of the gulf. 



QUANTITATIVE DISTRIBUTION OF THE ZOOPLANKTON 



To give an adequate quantitative picture of the plankton would require a far 

 greater number of vertical hauls than have yet been made in the Gulf of Maine. Not 

 only are the seasonal gaps in the series serious, but hauls should be located closer 

 together than has been feasible for us, even in July and August, unless the plankton is 

 more uniform than our work suggests. However, even a cursory examination of the 

 zooplankton, if extended over a considerable area or through a considerable period of 

 time, is certain to reveal wide fluctuations in abundance as well as in its qualitative 



