Influences of trans-molting retentive external eye (TRAMORE) tagging on predator avoidance ability in kuruma prawn (Penaeus japonicus) juveniles

The trans-molting retentive external eye (TRAMORE) tag is inexpensive, easy to apply, and immediately detectable without specialized detection devices. Its conspicuousness ensures almost no risk of consumption by humans, and it does not affect the survival and growth of Penaeus japonicus juveniles under experimental conditions without predation risks. However, during predator escape, the TRAMORE tag may become an obstacle during submerging into sand and/or swimming. Similar to traditional marking methods such as uropod ablation for identifying released individuals, little is known about whether TRAMORE tagging increases predation risk. If it does, the effectiveness of stock enhancement programs might be underestimated. This study aimed to determine whether TRAMORE tagging and uropod ablation marking influence the predator avoidance of P. japonicus juveniles through laboratory experiments. The time required to submerge into sand was not significantly affected by TRAMORE tagging nor uropod ablation marking. Neither TRAMORE tagging nor uropod ablation marking significantly affected the angle and distance of escape jumps. However, uropod ablation marking significantly slowed escape speed. These results indicate that the newly developed TRAMORE tag is more suitable for identifying released P. japonicus juveniles than the traditional uropod ablation marking method.