In the group of females receiving 10 daily injec- 

 tions of 5 mg, three fish were refractory with low 

 GSI values (10-15'^>f ), and three hydrated but did 

 not ovulate. Two of the latter fish contained a 

 small number of Stage II ova; the other developed 

 a cloacal plug of membranous tissue and Stage I 

 ova. 



In the group receiving 10 daily injections of 10 

 mg, all were refractory with low GSI values (9- 

 1 17( ), except for one fish that hydrated but did not 

 ovulate. A membranous plug developed in the 

 cloaca of this fish, and it was bloated. A very small 

 number of Stage II ova were found in the ovaries. 

 There was no indication of sexual ripening in the 

 uninjected control fish, and their GSI values were 

 low dO-lS'^). Copious semen was obtained from 

 the males injected at all three dosages; however, 

 fertilization was not attempted. It was reasoned 

 from the first trial that low GSI values (7-159r ) of 

 females coupled with low water temperatures 

 (3°-6°C, mean 5.1°C) that were less than optimum 

 inhibited the effectiveness of the hormones, for 

 although some fish hydrated, they did not ovulate. 



Second Trial • 



The results obtained from the second trial were 

 variable (Table 2). All but one fish receiving injec- 

 tions of 2 mg hydrated and ovulated. Two fish died 

 during the trial; one, after yielding spawn on two 

 occasions, developed a membranous plug and be- 

 came grossly bloated. 



In the group receiving injections of 5 mg, two 

 fish ovulated but the eggs obtained were not fer- 

 tile. Three other fish developed plugs and hy- 

 drated to the point of death. Injections were dis- 

 continued at the first sign of abnormal hydration, 

 but the fish continued to imbibe water. 



In the group that received 10 mg, five fish ex- 

 perienced excessive hydration manifestated by 

 bloating, plug formation, and, in two instances, 

 death. The membranous plugs were identical to 

 those that developed in the test group that re- 

 ceived hormone dosages of 5 mg. The controls had 

 four fish with signs of hydration but no Stage III 

 ova were found in their ovaries. 



Third Trial 



The results of the third trial paralleled those of 

 the second trial at a dosage of 2 mg. Seven of the 

 experimental females hydrated normally and ovu- 

 lated (Table 3). Fertilization and hatching of these 



eggs were satisfactory and the larvae were nor- 

 mal. The remaining two fish died during the trial, 

 and their ovaries had a small number of Stage III 

 ova. The control fish neither hydrated nor ovu- 

 lated; GSI values were fairly high, but Stage III 

 ova were absent. 



The anomalous hydration with bloating and 

 formation of membranous plugs during hormonal 

 induction is not unique. Clemens and Grant ( 1964) 

 injected female goldfish, Carassius auratus, with 

 carp pituitary and observed that the gonadal 

 water content increased, apparently in association 

 with ovulation. The hormone regulating the hydra- 

 tion process appeared to be a gonadotropin. 



Shehadeh and Ellis (1970) reported the forma- 

 tion of plugs in the cloaca in striped mullet, Miigil 

 cephaliis, treated with a combination of salmon 

 pituitary and Synahorin. Sinha ( 1971 ) studied the 

 gonadal hydration response of Puutis gonionotus 

 using the second fraction of molecular seived carp 

 pituitary extract and suggested that the second 

 fraction is involved in osmoregulation, since an 

 injection of an additional amount enhances the 

 rate of water transport resulting in maturation. 



Hirose and Ishida (1974) studied the effects of 

 Cortisol and human chorionic gonadotropin 

 (HCG) in ayu., Plecoglossus altiuelis, and reported 

 that the water content of the ovary from 

 hormone-treated fish increased by 6%. Smigielski 

 (1975b) reported a similar response in winter 

 flounder injected with pregnant mare serum 

 (PMS) and HCG. Hirose ( 1976) demonstrated that 

 gonadotropin-treated ayu imbided a greater quan- 

 tity of water than control ayu. He suggested that 

 gonadotropin may act on the sodium and po- 

 tassium system or permeability of the egg mem- 

 brane. 



Hydration is a normal and necessary prelude to 

 maturation and ovulation. The cases of abnormal 

 hydration experienced with yellowtail flounder 

 may be attributed to an adverse reaction to hor- 

 mone dosage. Most of the test fish that hydrated 

 abnormally and became bloated had an increase in 

 body weight of more than 10%. The increase in 

 body weight appeared to be a result of the fish 

 imbibing an excess amount of water. An excessive 

 amount of introduced hormone may upset the 

 water transport or sodium potassium systems, re- 

 sulting in more water bing imbibed. 



In conclusion, it appears that water tempera- 

 tures higher than 6°C and GSI values approaching 

 209^^ coupled with carp pituitary injections ap- 

 proximating 2 mg/kg offish is an effective combi- 



933 



