40 Tj. s. bureau of fisheries 



investigations of fish and fisheries 

 atlantic coast 



LIFK HISTOKIES AND MIGRATIONS OF COD, POLLOCK, AND HADDOCK 



An investigation of the early development of cod, pollock, and 

 haddock off the New Engjland coast, begun on May 1, 1924, by Dr. 

 Charles J. Fish, was continued throughout the past year. The 

 problem — an exhaustive study of conditions existing during the 

 period of incubation of the eggs, the early larval history, the food 

 during this period, the enemies, and the gradual changes in the 

 feeding habits and migrations during the first year of existence — 

 has been divided into two parts. The first part covers the period of 

 the ]5elagic existence of the young, and consists of hydrographic and 

 plankton surveys of the breeding grounds. The cleterniination of 

 the exact location of the spawning centers, the period of spawning, 

 and the relative production and distribution of eggs form an essen- 

 tial part of this work. An investigation of the migrations, feeding 

 habits, and enemies of the young fish after they leave the surface 

 waters and enter the shallow shore zone forms the second part and 

 necessitates seining and trawling over extensive areas along the 

 shore. 



In order not to delay the work, the second part of the problem was 

 begun first, and throughout the summer of 1924 the steamers Gaiinet 

 and PhalarojJe were utilized in a survey of the coast from Mount 

 Desert, Me,, to Woods Hole, Mass. During August and September 

 the Gannet covered 1,545 miles and towed the Petersen young-fish 

 trawl over 1,100 miles. 



As the lack of an adequate ship prevented a survey of the outer 

 banks, Massachusetts Bay was selected as the most suitable area in 

 which to begin observations on the early life history of the cod. 

 The Fish Hawk was assigned to this work in November, when the 

 fall spawing season began. Cruises were made covering the in- 

 shore breeding grounds of the bay south of Cape Ann. The Ply- 

 mouth grounds were found to be by far the most important cod- 

 spawning area in the bay, while pollock eggs were found in the 

 greatest numbers in the region of Stellwagen Bank. 



The steamer Gannet Avas occupied in similar observations in the 

 Gulf of Maine, concentrating particularly on the region about 

 Sheepscot Bay, where each year at the height of the spawning season 

 great quantities of fresh water pour out from the rivers over one 

 of the most important spawning areas of the coast. What effect thi^ 

 influx of low-density water has upon the eggs is as j'et unknown. 



As the work has just begun any conclusions made at this time must 

 necessarily be of a very general nature. However, some very signifi- 

 cant and interesting results have been obtained. Upon reaching the 

 post-larval stage the cod and pollock seek shalloAv water, and in 

 April and May are taken, often in large numbers, along the shores. 

 The smallest specimens of both species taken with the seine were 

 found to be feeding almost entirely on Harpactid copepods, probably 

 most nearly like the free-SAvimming copepods of the surface waters. 

 Later they Avere taken filled with mysids, amphipods, and in fact 



