World Aquaculture Singapore 2022

November 29 - December 2, 2022

Singapore

DEVELOPMENT OF CRYOGENIC SPERM BANK OF SILVER CARP Hypophthalmichthys molitrix AND SEED PRODUCTION IN COMMERCIAL HATCHERIES FOR BROOD BANKING

M Matiur Rahman*, M Abdur Razzak, M Rafiqul I Sarder, Mariom and Terrence R Tiersch

 

*Department of Fisheries Biology and Genetics

 Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

 



Quality of hatchery produced seeds of the exotic species, Silver carp (Hypophthalmichthys molitrix) is deteriorating day by day in Bangladesh due to intergeneric hybridization with other Chinese carps resulting in failure of achieving expected production by the farmers. Therefore, development of cryogenic sperm bank of silver carp has become a demanding issue to overcome such problems. This investigation was carried out for standardization of sperm cryopreservation protocol of silver carp and production of quality seeds using cryopreserved sperm in commercial fish hatcheries. Broodstock of silver carp was developed by rearing newly imported silver carp fingerlings from China in earthen ponds using supplementary feeds. Activation of sperm motility was evaluated with different concentrations of NaCl solution (0.1% to 1.2% NaCl) among which 0.4% showed the highest motility (97.3±0.9%) and swimming duration (28.12±1.5 min). Motility of sperm was severely inhibited at 1.2% NaCl. The toxicity of cryoprotectant (DMSO and methanol) to sperm was tested at different concentrations (5%, 10%, and 15%) and with incubation time (5-40 min) with two extenders (Alsever’s solution and egg-yolk citrate). Cryoprotectants at 5% and 10% concentrations produced better motility during 5- and 10-min incubation periods, respectively. Alsever’s solution with 10% DMSO at 1:12 dilution (sperm: diluent) with 15 min incubation time displayed highest equilibration motility (93.3±1.2%) and post-thaw motility (91.0±0.6%) during cryogenic freezing. The quality of sperm in cryogenic sperm bank was assessed by observing post-thaw motility at 30 days interval over the twelve-month storage period and a slight decrease in motility from 82.67±1.5% to 87±1.7% was observed. Seeds of silver carp were produced through induced breeding in 10 commercial government and private hatcheries in different geographic locations using both cryopreserved sperm (treatment) and hatchery-originated fresh sperm of males (control).  The average fertilization and hatching rates of eggs for cryopreserved sperm and fresh sperm were determined as 39.73% and 29.95±8.74%, and 73.16±10.49% and 59.24±9.95%, respectively. The seeds produced from both treatments and controls are separately stocked in respective hatcheries as well as in some technology adoption hatcheries and are being reared for observing growth performances. The initial sampling data revealed higher growth in cryopreserved sperm-originated seeds compared to control.