Seasonal studies of caviar production and the growth rate of the African catfish (Clarias gariepinus, Burchell, 1822)

Abstract

Issues of African catfish caviar production organization were studied in the present work. Prospects of all-season African catfish caviar production in recirculating aquaculture system were investigated. The purpose of the study was to evaluate season-dependent dynamics of caviar production, duration of pre-spawning period and dynamics of postembryonic ontogenesis of African catfish generations, reproduced within autumn-winter and spring-summer periods. The tasks of the study included: comparative analysis of male and female pre-spawning periods in different seasons; hormonal stimulation; eggs fertilization; eggs growth to larval stage; evaluation of dynamics of larvae and fry growth reproduced in spring and autumn period. The study results showed that caviar productivity of African catfish females, characterized by multiple spawning, decreased by two times in November as compared to spring period, and depended on the duration of pre-spawning period. Dynamics of gonads development was also season-dependent. In autumn period the duration of pre-spawning preparation, necessary for gonads maturation, was twice as long as spring one. Males and females did not respond to hormonal stimulation if pre-spawning conditions failed to comply. Growth rate of African catfish larvae and fry, reproduced in autumn period, was slower as compared to those that were reproduced in spring.