COD EGGS IN MASSACHUSETTS BAY, 1924-1925 



283 



of No. 108, from the same station, was 2.9 miles. It is hardly justifiable to give the 

 average rate of all bottles for this cruise, because the courses taken by those within 

 Cape Cod Bay are not definitely known, and such bottles as Nos. 112 and 118 

 evidently had been on the beach for some time. 



The returns from the bottles placed along the north shore of the bay (stations 

 36 to 38) proved rather surprising. The general courses taken agreed with expecta- 

 tions, being carried either directly inshore by the tide or drifting westward with 

 the set of the current. (Nos. 136 to 141.) However, it was not expected that the 

 rates would be so slow. It is hardly probable that they could have grounded at 

 such widely separated places and, after lying on the shore for several days, all be 

 found within such a short period. No. 136 evidently had been ashore for some time 

 when recovered, but the other four bottles set out on May 22 were recovered on 

 May 27, 28, 31, and June 1. The average rate of Nos. 137 and 141, which were 

 carried west, was 0.92 mile per day. Bottle No. 120, found drifting 75 miles off 

 Highland Light, had traveled a minimum distance of 91 miles at a rate of 4.1 miles 

 per day. 



To summarize the evidence shown by bottle movements in Massachusetts 

 Bay, the greater part of the cod eggs spawned in winter and early spring probably 

 move east directly across the bay at a rate of 3 to 4 miles per day. In the late spring 

 the drift certainly is not diminished and, as shown by bottle No. 120, may retain 

 a rate of 4 miles for at least 90 miles. 



The spawning grounds in Ipswich Bay, situated just north of Cape Ann, are 

 in a favorable position to form a source of supply for Massachusetts Bay, for they 

 lie in the path of the westerly drift. Regarding this drift, Bigelow and Welsh (1925, 

 p. 75) state that "fish eggs and larvae, and for that matter every member of the 

 plankton, animal or vegetable, tend to follow the same peripheral migration zone 

 as do the immigrants that enter the eastern side of the gulf in the upper 50 meters. 

 Only such buoyant eggs as are spawned among the islands, in bays, or close in along- 

 shore (as most of the cunners are) are likely to escape this dominant set. " 



Three trips were made to the regions lying between the Isle of Shoals and Cape 

 Ann. (Fig. 5.) The data obtained from these few observations are hardly suffi- 

 cient to explain the conditions existing throughout the season but clearly indicate the 

 movement of the eggs. At the time of the first trip (March 12) considerable spawning 

 was taking place, and an average of 64 cod-haddock eggs was obtained at each of five 

 stations. (See Table 5.) On March 25 the average rose to 117 and on April 7 to 127 

 eggs per station. 



The stations were arranged in two parallel lines (fig. 5), and on every trip the 

 number of eggs taken on the western (inshore) line was by far the greatest, thereby 

 indicating an alongshore and not a seaward drift. The following table, giving the 

 quantitative distribution of eggs on trip 10, illustrates this movement. The two 

 lines were only about 2 miles apart. 



IPSWICH BAY 



