| dc.description.abstract | Naturalized rainbow trout (Oncorhynchus mykiss) populations form important recreational fishing resource in the world. Globally, rainbow trout is among the most widely introduced fish species and has been translocated outside its native home range, into at least 99 countries including the tropical regions where it has established naturalized populations. Information on the performance of the hatchery and wild populations of O. mykiss following spawning interactions has not been adequately explored especially in the tropical environments. The current study aimed at evaluating the spawning interactions between naturalized and wild O. mykiss from the high altitude second order stream, the Sagana in Kenya. Spawning and incubation were performed under controlled conditions in a hatchery facility to assess their performance. In each spawning process, total length, weight, condition factor and fecundity of the brooders were recorded. Fertilization rate, hatchability and survival of the fry were determined. Egg diameters were modelled as a function of biometric and reproduction parameters, using generalized linear model. Total fecundity of the broodstock differed significantly among the wild strain, hatchery reared and the cross between hatchery and wild stock (F = 8.934, df = 2, P = 0.0045). The fecundity of the broodstock varied with the average weight of the brooders where brooders with high average weight had a high fecundity. Relative fecundity was significantly different among the three groups of fish (F = 6.134, df = 2, P = 0.0217) but the differences between the hatchery and cross strain of wild and hatchery fish were not significant. Fertilization rate showed significant differences among fish in the three experimental groups (F = 10.136, df = 2, P = 0.0057), Eyed egg survival was lowest among the wild fish but showed no significant differences between the hatchery and cross between wild and hatchery strains. The study recommends the use of hatchery and wild crossed fish to support fry production for use in subsequent restocking of all trout streams in the country. Based on this study, management strategies involving restoration of trout population that would benefit anglers without reliance on importation of eyed eggs are recommended. | en_US |
