The Analysis of reproductive characteristics of the rainbow trout

SUMMARY The Analysis of Reproductive Characteristics of the Rainbow Trout (Oncorhynchus my kiss). The main objectives of this study were to determine the total fecundity, fertilization, eyeing and hatching rates, larval development and survival of rainbow trout (Oncorhynchus mykiss). The study started stripping of the broodstock on 30 January 1995 and continued until 19 July 1995 (133th day after hatching). After weighing both males (n=22) and females (n=25), females were stripped into separate bowls and milt from at least two males were used for fertilizing the eggs. Total egg volumes and egg diameters for each females were measured using a measuring cylinder and a von Bayer trough, respectively. Five hatching trays were divided into five compartments and were used for incubation. Development of fertilized eggs and hatched larvae were observed until fingerling stage. Mean total and relative fecundities were 2304±425 egg/individual and 1364±281 egg/kg body weight, respectively, while egg diameter varied between 4.9 -5.7 mm with a mean of 5.19±0.21 mm. On average 24.9% of those stripped died during first 3 days, i.e. fertilization rate was 75.1% of total egg number. 87.8% of the fertilized eggs was eyed and 96.4% of eyed was hatched. Larvae reached free swimming stage after 23 days and survival rate was determined as 98.9% of total hatched larvae. Larvae reached a mean weight of 305±56 mg at 40*1 and 19.2±5.41 g 133*1 days after hatching. There was not any significant relationship between weights of hens and fecundity, egg diameter, fertilization, eyeing and hatching rates and larval quality. It has been concluded that those values determined during this study seems to be quite satisfactory for a trout farm which has not got any broodstock management strategy other than renewing 1/4 of the stock every year. Keywords: Trout, The Rainbow trout, Oncorhynchus mykiss, Egg Production, Reproduction VI