SMIGIELSKI: OVULATION OF WINTER FLOUNDER 



noted nor did any plugs form in the test fish. A 

 weight loss occurred in almost all of the test fish at 

 the lower temperatures. 



Administering DOCA at lower temperatures 

 resulted in GSI levels being higher in test fish at all 

 three dosage levels. Several fish hydrated and 

 although no ovulation occurred, some matured 

 eggs were present in the ovaries of two test fish 

 that received injections at the higher levels of 10 

 and 20 mg. No plugs were present in any of the 

 test fish and no abnormal hydrations were ob- 

 served. 



Tests with PMSG in the lower temperature 

 range resulted in some fish at all three dosage 

 levels hydrating but not spawning. Plugs formed 

 in the oviducts in two of the fish that received 

 dosage levels of 55 and 220 lU respectively. Eggs 

 were water hardened in one and were nonfer- 

 tilizable. Approximately 20% of the total eggs ob- 

 tained from the second fish were fertilized. These 

 eggs were normal in size and the majority of them 

 developed and hatched. The larvae obtained from 

 this induced spawning appeared to be normal in all 

 respects and several were reared through 

 metamorphosis. 



HCG administered at the level of 200 lU at 

 lower temperatures produced ovulation in one fish, 

 and 4 days after the last planned injection it was 

 spawned. The eggs obtained were normal in size 

 and appearance. Approximately 95% were fer- 

 tilized and approximately 80% developed and 

 hatched. The larvae obtained from this hormone- 

 induced spawning appeared normal in all respects 

 and many were reared through metamorphosis. 

 One other fish that received the higher dosage 



level of 400 lU had a plug form in the oviduct and 

 approximately 15% of the eggs present in the 

 ovaries were mature. These eggs were spawned 

 and fertilization was successful. All development 

 halted at the blastula stage and none survived to 

 hatch. 



The limited success that was obtained with the 

 hormones oxytocin, DOCA, PMSG, and HCG ad- 

 ministered alone is apparent. It is hoped future 

 studies will evaluate the synergistic actions of 

 various hormone combinations administered to 

 winter flounder. 



Two test fish that received injections of carp 

 pituitary at the level of 5.0 mg ovulated and were 

 stripped (Table 5). The eggs obtained from these 

 induced spawnings were in the normal size range 

 of winter flounder eggs and approximately 90-95% 

 were fertilized. The majority of them developed 

 normally and approximately 85% hatched. The 

 larvae appeared normal in all respects and many 

 were reared through metamorphosis. At the 

 dosage level of 0.5 mg, three fish ovulated and were 

 spawned after receiving three to six injections. 

 During the time of injecting these fish hydrated 

 normally. The eggs obtained from these induced 

 spawnings were normal in size and approximately 

 95% were fertilized. Their development was nor- 

 mal and approximately 70-85% survived to hatch. 

 Larvae obtained appeared normal in all respects 

 and several were reared through metamorphosis. 



All of the uninjected controls at the conclusion 

 of the trials displayed signs of hydrating. Four out 

 of the six fish were sacrificed and GSI levels 

 recorded. The remaining two fish that displayed 

 the best signs of hydration were spared and 



Table 5.-Effects of carp pituitary on Pseudopleuronectes americanus. All fish experienced a 9L:15D photoperiod, water temperature 



range 1.5°-3.5°C (x 2:5°C). Symbols (+ = Did, = Did not hydrate or ovulate). 



'Gonadosomatlc index. 



^Sexually immature. 



^Ovulated and spawned 46 days after termination of testing trials. 



437 



