FISHERY BULLETIN: VOL. 73, NO. 2 



allowed to continue to develop without interrup- 

 tion. After 46 days they ovulated and were 

 stripped. 



The ability of carp pituitary as an aid in induc- 

 ing spawning in winter flounder was dramatically 

 shown in these trials. At least six additional weeks 

 of research time was able to be realized when carp 

 pituitary was administered in conjunction with 

 low water temperatures (1.5°-2.5°C). It is hoped 

 that future tests will be initiated to evaluate the 

 effectiveness of various dosage levels and at 

 warmer water temperatures. By controlling pho- 

 toperiods and water temperatures and injecting 

 carp pituitary it may be possible to extend the 

 research time on the eggs and larvae of this 

 species of flatfish in the laboratory for several ad- 

 ditional months through induced spawnings. 



In conclusion, it would appear that water 

 temperature may be the most critical factor in 

 producing ovulation; and while the administering 

 of hormones was effective in producing hydration, 

 hydration alone is not suflScient to initiate ovula- 

 tion. Low GSI levels below 12% in conjunction with 

 water temperatures above 6°C resulted in the 

 majority of test fish not hydrating regardless of 

 the hormone administered. 



Hormone treatments had a range of effects 

 depending on the degree of ovarian maturation; 

 test fish in the later stages of development re- 

 sponded while less mature fish developed higher 

 GSI levels but did not ovulate and spawn. No 



evidence was discovered indicating that spawning 

 induced by hormones produced abnormal larvae. 



ACKNOWLEDGMENTS 



The author wishes to express his appreciation to 

 Hugh A. Poston of the Tunison Laboratory of Fish 

 Nutrition and Geoffrey C. Laurence of the Na- 

 tional Marine Fisheries Service, NOAA for their 

 many helpful criticisms of the manuscript. 



LITERATURE CITED 



BiGELOW, H. B., AND W. C. SCHROEDER. 



1953. Winter flounder Pseudopleuronectes americanus 

 (Walbaum) 1792. In Fishes of the Gulf of Maine, p. 276- 

 283. U.S. Fish Wildl. Serv., Fish. Bull. 53. 

 Dunn, R. S., and A. V. Tyler. 



1969. Aspects of the anatomy of the winter flounder ovary 

 with hypotheses on oocyte maturation time. J. Fish. Res. 

 Board Can. 26:1943-1947. 



Haydock, I. 



1971. Gonad maturation and hormone-induced spawning of 

 the Gulf croaker, Bairdiella icistia. Fish. Bull., U.S. 

 69:157-180. 



Pickford, G. E., and J. W. Atz. 



1957. The physiology of the pituitary gland of fishes. New 

 York Zoological Society, N.Y., 613 p. 

 Shehadeh, Z. H., and J. N. Ellis. 



1970. Induced spawning of the striped mullet Mugil 

 cephalus L. J. Fish. Biol. 2:355-360. 



Smigielski, a. S., and C. R. Arnold. 



1972. Separating and incubating winter flounder 

 eggs. Prog.-Fish Cult. 34:113. 



Stevens, R. E. 



1966. Hormone-induced spawning of striped bass for reser- 

 voir stocking. Prog.-Fish Cult. 28:19-28. 



438 



