Fin-spines attachment,a novel external attachment method for the ultrasonic transmitters on hard fin-spines fish (Sparidae)

The purpose of this study was to develop a novel method for the external attachment of ultrasonic transmitters on hard fin-spines fish (Sparidae). Acanthopagrus latus, one of the main stocking Sparidae fishes in the northern South China Sea, was employed to conduct the 40-day tank experiment by using dummy ultrasonic transmitters. The experiment consisted of 3 treatment groups, i.e., drilling on dorsal fin-spine (DD) group, drilling on anal fin-spine (DA) group, and control (C) group, with each group having 3 replicates and 30 fish per replicate. The feasibilities of DD and DA for the external attachment of ultrasonic transmitters were tested and evaluated using parameters: the specific growth rate, survival rate, and tag retention rate of each group. And the tagging procedures for the external attachment of hard fin-spines fish were also proposed. The results showed that there were no significant differences in the specific growth rate of fish between groups. Both the survival rates of DD group (96.67%) and DA group (94.44%) were less (but not significant) than C group (97.78%), while the tag retention rate of DA group (100%) was higher (but not significant) than DD group (98.89%). These results demonstrate that drilling on dorsal or anal fin-spines is feasible as an external attachment method of ultrasonic transmitters on Sparidae fishes. In addition, considering the friction between the tagged transmitters and rocks at the bottom of natural waters, which possibly affect the fish behaviors such as swimming, feeding, etc., or lead to tag loss, so drilling on the dorsal fin-spine is preferred for rocky-bottom Sparidae fishes like A. latus as small as 14 cm body length.