Studies On Key Techniques In Incubation, Culture And Transportation Of American Shad Alosa Sapidissima

With growth and development, the larvae and fingerlings showed obviously stressful to flash light, noise, handling, and transportation, which would cause the low survival rate and low growth rate in culture. Tank transference and long-distance transportation of fingerlings could hardly realized for the subsequent high mortality of the fish, which had became the bottlenecks in scale-cultivation and industrialization of the American shad. The author mainly studied on the transport stress and transport technology. Conclusions of the studies are as follows:1 Water temperature, water quality and dissolved oxygen (DO) were the important factors in incubation and culture of American shad. The suitable water temperature for incubation is between 17℃ and 20 ℃ and larvae died soon after hatch when the water temperature was above 23 ℃ . The Hatch rate in underground water with high concentration of the heavy metals was lower than in lake water. The larvae and fingerlings were observed died when the DO were below 2.5mg/L and 3.2mg/L respectively. Regular water exchanging and dirt cleaning, good water quality and high DO will make for better growth and development of American shad.2 Larvae in early stage(8-20 day-age) after hatch had high survival rates in the incubation barrel with the high density of plankton and turbulent current contrary to larvae in latter stage(20-33 days old). High survival rates were obtained in capacious tanks from larvae to fingerlings.3 Larvae and fingerlings of American shad were obviously stressful to flash light, noise, handling, and transporting, which were the main factors on limiting the survival, growth and development of the fish.4 MS-222, clove oil and bezuocaine had the same anaesthesia effect to American shad fingerlings, which would stop opercular movement in high concentrations and even could not be recovered, while could not be well anaesthetized in low concentration. The anaesthesia effects were enhanced in higher water temperature while were no obviously different with fish size. The concentration of MS-222 with 20-30mg/L, clove oil with 8-10mg/L and benzuocaine with 20-30mg/L were thought to be suitable for short or long distance transport.5 Behaviors of the American shad fingerlings in stages of anaesthesia or recovery were observed and the results showed that whether the fish were anaethetic or not, they collided with the container when they were transferred to smaller containers. Four hours later in fresh water, serum cortisol of the unanaesthetic fish increased 5-7 times higher than the initial lever. With the time went on, the blue-green back of the fish would got red and the head, eyes and the base of the each fims of the fish would hemorrhage and then the fish would die. So, this behavior would caused the failure in long distance transport ofthe fish. Short distance transference of the fish with anaethetics between the tanks were successfully realized. The 2500 fingerlings were successfully distributed to 10 tanks with 100% survivial rate.6 Long distance transport of the American shad fingerlings from Jingzhou to wuhan were conducted with plastic container by truck(PCT) and live-fish carrying truck(LFCT). The results showed that fish transported with no anaethetic were all died and the survival rate of the fish transported with PCT with 1 fish/bag and 5 fish/bags were 63.3% and 56% respectively, higher than that transported with LFCT(36.6%). It was the colliding of hard carriage wall with the fish that caused the failure in transport with LFCT. Follow this, the author designed the ideal container for the long distance transportation with LFCT.7 hi order to understand the mechanism of the high mortality in transportation, we investigated the changes of hormonal (cortisol) and blood biochemical parameters in 1+ year old American shad fingerlings with unstressed fish before transport (Initial-fish), fish after 2 hrs transport without anesthetics (I-fish) and fish after 2 hrs transport with 20mg/L anesthetic benzocaine (BZ-fish). The results showed that the serum cortisol and blood biochemical parameters were obviously changed after transportation. The serum cortisol in I-fish and BZ-fish are obviously higher than in Initial-fish and serum cortisol in I-fish was alse obviously higher than BZ-fish (p<0.05). The concentrations of serum TP, AP, AKP, CHE, ALT, K+ and Ca2+ in I-fish were obviously higher but values of AP/GP and AST/ALT were obviously lower than in Initial-fish(p<0.05). No significant difference of the blood biochemical parameters mentioned above were observed between BZ-fish and Initial-fish. The concentrations of serum LDH and AST in I-fish and BZ-fish were no obviously higher than Initial-fish (P>0.05) The concentrations of serum y-GT> GLLU TCn TG in I-fish showed no significant difference with Initial-fish but were obviously different to BZ-fish (p<0.05). The results also showed that the anesthetic benzuocaine had catabatic effect to the transport stress.8. Serum cortisol hi fingerlings after 2hrs transport with 20mg/L MS-222 or 10 mg/L clove oil with 10%o NaCl were obviously lower than that without NaCl(p<0.05) and it was not different after 2hrs transportation with 20 mg/L benzuocaine with or without l%NaCl.The results showed that NaCl also had catabatic effect to the transport stress. More proofs were required.