1Tohoku National Fisheries Research Institute, Fisheries Research Agency, Shiogama, Miyagi 985-0001, 2Miyako Laboratory, Tohoku National Fisheries Research Institute, Fisheries Research Agency, Miyako, Iwate 027-0097, Japan
We examined the effectiveness of punching based on the small regenerated scales on the ocular side as a new method for the external marking of spotted halibut Verasper variegatus and compared it with conventional branding. Juvenile spotted halibut (9.8 cm in total length) were individually marked by punching from the ocular side or branding from the ocular or abocular side, and the wound healing process was observed. Results showed the presence of small regenerated scales in all experimental groups that did not disappear two years after marking. Less variation in perforation diameter was observed on the ocular side after punching, and punching demonstrated the highest distinguishability rate. No mortality or growth suppression was observed due to punching. The mean rate at which juveniles could be marked by punching was 504 individuals per hour per worker. Therefore, punching was more effcient than the other marking and tagging methods. These results show that punching could be a useful method for marking juvenile spotted halibut for seed stocking.