EFFECT OF MONTHLY VARIATION IN WATER TEMPERATURE ON ARTIFICIAL BREEDIN…
The effect of monthly variation in water temperature on artificial breeding of common carp, Cyprinus carpio using ovaprim as an ovulation stimulator was studied. Two years old common carp broodstocks weighing 800-2500grams were obtained from Panyam fish farm in Jos, Nigeria. They were transported to the Department of Biological Sciences, Ahmadu Bello University, Zaria, Nigeria and maintained on commercial feed at 3% body weight for a period of two months before the breeding exercise. A total eighteen (18) broodstock were divided into three (3) temperature groups of 23±1, 26±1 and 29±1°C. Each group had three (3) female and three (3) male brooders. Effect of female body weight on fecundity of common carp was also evaluated. Ovaprim hormone at dosage of 0.5ml/kg and 0.2ml/kg was administered intramuscularly to female and male brooders respectively and simultaneously. Temperature has significant effect (p≤0.05) on latency period of C. carpio; latency period decreased with increase in temperature. At 23±1°C, latency was found to be 16.55±0.13 hours, at 26±1 and 29±1°C latency was 13.00±0.13 and 11.32±0.07 hours respectively. While temperature had no significant effect on the weight of eggs, fecundity and viability of the eggs of C.carpio, increase in female body weight yielded a significant increase (r= 0.97) in the weight of eggs and fecundity of C. carpio. The present results showed that temperature has a significant effect (p≤0.05) on fertilization and hatchability. C. carpio performed best at 26±1°C in terms of fertilization (89.00±3.00%) and hatchability (67.50±2.50%) followed by the temperature of 23±1°C with fertilization of 72.67±1.76% and hatchability of 46.83±0.84%, while the temperature of 29±1°C gave fertilization of 52.30±10.49% and hatchability of 28.98±0.96%. There was also a high significant difference (p≤0.05) in hatching duration of C. carpio eggs incubated at different water temperatures, increase in temperature leads to decrease in the hatching duration of C. carpio eggs. Hatching duration was found to be 41.96±0:42 hours at the temperature of 23±1°C, at 26±1°C hatching duration was 37.18±0:04 hours and 28.98±0.96 hours at 29±1°C. There was an increase in survival of larvae with increase in temperature (r = 0.67) though there was no significant difference (p≤0.05) in the survival of larvae between the three temperature groups. At 23±1°C survival was 15.27±0.52% while at 26±1 and 29±1°C survival was 33.20±1.60 and 30.13±6.29% respectively. It is concluded that C. carpio can be successful reproduced artificially with ovaprim within the temperature range of 23±1 to 29±1°C, and optimally at 26±1°C. It is therefore recommended that the temperature of 26±1°C be used during artificial breeding of C.carpio in Nigeria.
1.1 Background of the Study
Breeding performance is an important parameter to evaluate the success of artificial reproduction of fish species in captive, which also depend on the environmental conditions, type of hormone used and its potency, dose of hormone and maturity status of the fish (Sahoo et al., 2007). The success of induced breeding also depends on the latency period (Bogdan et al., 2010); appropriate combinations of inducing agents and stripping time always yield maximum egg output during induced breeding while improper coordination between these two will lead to breeding failure (Kiran etal., 2013).
Fish reproduction is regulated by a number of environmental factors which stimulates internal mechanisms into action; the final product of the reproductive cycle is the release of eggs and sperm, which can be controlled by either placing fish in an appropriate environment or by stimulating the fish‟s internal regulating factors with hormones or other stimulants (Amer et al., 2009). The precise combination of environmental factors and hormonal treatments required for maturation, ovulation and spawning when available, brings about an accelerated release of gonadotropin from the pituitary into the blood stream. As a result, gonadotropin, which was hitherto being secreted only at a tonic level for the maintenance of yolky oocytes, suddenly appears as a surge, and then the elevated titres of gonadotropin bring about maturational changes culminating in the act of spawning (Pao et al., 2003).