Abstract
Chinese carps, namely silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis) and grass carp (Ctenopharyngodon idella) have the largest annual production in freshwater aquaculture globally. Induced breeding of these species enlarged the geographical range for their culture as well as permitted more reliable seed supply. For the assessment of efficiency, long-term data from 18 spawning seasons on induced breeding of Chinese carps at a large-scale hatchery were evaluated. Assessment of ovulation was carried out by determining the ovulation ratio (number of ovulated females / number of injected females) × 100. The relative amount of stripped eggs (pseudo-gonadosomatic index, PGSI) was calculated as follows: (weight of stripped egg mass / body weight before stripping) × 100. We also analyzed the ovulation ratio and the PGSI relative to three different weight classes of females (small, medium and large).Over the 18 spawning seasons, 555 silver carp, 300 bighead carp and 1175 grass carp females were selected for propagation. Almost 80% of silver carp females selected belonged to categories between 4 and 7 kg. For grass carp and especially for bighead carp, breeders preferred higher weight categories.Ovulation ratios were similar between silver carp (80.9%), bighead carp (77.3%) and grass carp (79.1%). Mean PGSI for grass carp (9.3 ± 4.26%) was significantly lower than that for silver carp (10.5 ± 4.85%) and bighead carp (10.1 ± 3.96). In silver carp and bighead carp, there were no significant differences in ovulation ratios and mean PGSI values among different weight classes. Mean PGSI values were also similar among different weight classes of grass carp females. Ovulation ratios, however, were different among the three different weight classes in grass carp being the lowest in the “small” weight class and the highest in the “large” weight class. These results will provide guidelines for Chinese carp breeders to select optimal brood fish for ovulation induction and calculate their hatchery's larval production in advance.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.