Improvements Of Fish Tagging Methods And Its Application On Yellowfin Seabream(Acanthopagrus Latus)

Acanthopagrus latus,one of the main stocking species in the northern South China Sea,was employed to conduct three indoor experiments in this paper.The optimal procedures using T-bar anchor tags were analyzed and a field protocol suggestion was proposed.Then,the suitable body size of A.latus for tagging with T-bar anchor tags was evaluated.Moreover,a novel external attachment method for ultrasonic transmitters was examined.These results will provide references for other fishes tagging studies in the future.The main results are described as follows:1.The optimization study of key procedures for tagging on A.latusAccording to a 2×2×2 factorial design,the experiment was divided into 8 tagged groups and 1 control group,with 3 replicates per group and 30 juvenile A.latus[initial average body length?10.05±0.39?cm]per replicate.Rates of growth,survival and tag retention after 40 days were evaluated quantitatively by multifactor analysis of variance.The results showed that there was no significant difference in the specific growth rate among groups?P>0.05?.Anesthetized or not was the factor that produced very significant difference in survival rate?P<0.01?.Tagging locations and implanted angles produced significant difference in tag retention rate?P<0.05?.Tagging by T-bar anchor tags with 45°for the anterior dorsal muscle of A.latus was the optimal procedures,which had the highest survival rate of 95.56%with tag retention rate of98.89%.Finally,the field protocol suggestion was proposed:?1?the fish should be reared no less than 3 days before tagged;?2?the tagging equipment should be sterilized using 75%alcohol for 5 minutes;?3?the fish should be anesthetized using30mg/L clove oil or MS-222 until they could not maintain equilibrium;?4?the fish should be tagged with angles of 45°for the anterior dorsal muscle;?5?the fish should be sterilized using 5%povidone iodine or KMnO₄ for 30 minutes;?6?the tagged fish should be then reared for 7 days before released.2.The suitability evaluation study of body size for tagging on A.latusFour sizes of A.latus?average body length of 5 cm,7 cm,11 cm and 14 cm?were tagged with T-bar anchor tags.4 tagged groups and 4 control groups were set,with 2 replicates per group and 20 juvenile A.latus per replicate.The relationship between probability of survival and body length of A.latus was fitted via logistic regression model.The results showed that there was no significant difference in the specific growth rate among groups?P>0.05?.Rates of tag retention after 40 days are high?97.5%for 7 cm group,100%for 11 cm group and 100%for 14 cm group?.The tagged fish of 5 cm group all died in a week,Rates of survival increase with the increases of body length?77.5%for 7 cm group,92.5%for 11 cm group and 100% for14 cm group?.The formula of logistic regression model is Pro=exp?0.099X-6.900?/[1+exp?0.099X-6.900?].According to the formula,the probability of survival was>95%for body length>10 cm.It is recommended that the body length of A.latus should be>10 cm for tagging and releasing.3.The feasibility study of a novel external attachment method for ultrasonic transmitters on A.latusThe experiment was divided into a dorsal fin spine drilling group,a anal fin spine drilling group and a control group,with 3 replicates per group and 30 juvenile A.latus[initial average body length?14.09±0.44?cm]per replicate.Rates of growth,survival and tag retention after 40 days were evaluated quantitatively by one-way analysis of variance and Kaplan-Meier survival analysis.The results showed that there was no significant difference in the specific growth rate among groups?P>0.05?.The survival rate was in a descending order of control group?97.78%?>dorsal fin spine drilling group?96.67%?>anal fin spine drilling group?94.44%?,and the tag retention rate was in a descending order of anal fin spine drilling group?100%?>dorsal fin spine drilling group?98.89%?,but there was no significant difference in both them?P>0.05?.We conclude that dorsal fin spine drilling is feasible as a method to attach the ultrasonic transmitters on the hard-fin spine fish like A.latus.