PROGRESS IN BIOLOGICAL, INQUIRIES, 1931 455 



stocks of commercial-sized cod on the offshore banks — especially 

 whether these grounds are self-supporting or whether they depend 

 in a large measure on immigration of juveniles and adults from other 

 grounds. The continued marking of 1, 2, and 3 year old fish in 

 the shore waters along the coast of Maine, an important nursery for 

 3^oung cod, is expected to throw some light on this question. In past 

 experiments in this region the marked fish have been rapidly caught 

 up bj' local fishermen and the tags were seldom carried by the fish 

 for more than a year. However, by marking in localities not ordi- 

 narily visited by fishermen and by using improved types of tags it 

 is hoped to trace the migration of these young fish when they be- 

 come older and move offshore. 



WINTER FLOUNDER 



As mentioned in the previous annual report, such concern has been 

 felt over the welfare of the flounder fishery that certain waters have 

 been closed by State law to flounder draggers during a portion of 

 the season, A comprehensive investigation is therefore urgently 

 needed to determine whether in fact this species is being overfished ; 

 and, if so, what practical methods of conservation should be adopted. 

 Though the means for such an investigation have not been available 

 to the bureau, a limited program was begun in 1931 that throws some 

 light on the pertinent question of whether the winter flounder 

 Pseudoplewronectes wmericanus^ migrates widely from place to place 

 or whether the various grounds have separate, self-perpetuating 

 populations. In the one case overfishing at any one place would 

 reduce the population at other places also. In the other case the 

 effects of overfishing would be felt only in the locality in which it 

 occurred. Obviously, this information is a preliminary necessity for 

 an understanding of the ability of the species to support the com- 

 mercial fishery and for designing protective measures if such be 

 needed. 



In Waquoit Bay, near the United States Fisheries Biological Sta- 

 tion, Woods Hole, Mass., a concentration of winter flounders regu- 

 larly occurs, many of which are spawning fish. Mixed with the 

 spawners are juveniles, immatures, and spent individuals. During 

 the period from February 13 to April 3, 1931, 4,179 flounders, both 

 young and old, were tagged and released. The work was done by 

 Kobert A. Goffin and Henry M. Bearse under Kobert A. Nesbit's 

 supervision. The tag used was similar to the Scottish plaice label, 

 consisting of two celluloid disks held together by nickel wire passed 

 through their centers. About half of the flounders were tagged just 

 below the dorsal fin immediately posterior to the head ; the remainder 

 at a similar point midway between snout and tail. 



Keturns to December 31, 1931, totaled 84 fish, exclusive of 56 which 

 were taken by the hatchery's fishing crew within 40 days of the time 

 of tagging and again released. These recaptures show that there 

 is a definite movement of flounders in spring toward offshore waters, 

 mostly eastward through Nantucket Sound, but with a few straying 

 westward through Buzzards Bay or Vineyard Sound. By summer 

 time tagged fish were recaptured for the most part in the open waters 



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