Evaluation of laser labeling on growth and survival of the freshwater pearl mussel, Hyriopsis cumingii

Laser labeling techniques have been developed for breeding programs in aquatic organisms through this study. This study assessed their use in Hyriopsis cumingii, an important Chinese freshwater pearl mussel. In preliminary studies, H. cumingii juveniles between 55 and 95?days old were labeled by a laser engraving machine. The mortality rate decreased in an age-dependent manner, no differences in growth between treated and unlabeled juveniles at 85 and 95?days of age. Hundred-day-old juveniles were labeled with four different sized labels. The mortality rate and growth inhibition were significantly higher with the largest label size (2.55?cm) compared to the smaller size and control. Four different types of laser intensity were applied to 100-day-old juveniles, but mortality rates and growth inhibition after high current treatments were significantly higher than the lower currents and control. The wing part, center, lower edge, left edge and right edge were labeled in different 100-day-old juveniles. Labeling of the left edge caused higher mortality and growth inhibition than the other sites. No significant differences were found after either side of the shell was labeled compared to the control. All labels remained clear without any deformation after several months. In summary, the optimal strategy for the laser labeling of H. cumingii would be in juveniles >85?days. The label size, laser intensity and positions could affect their growth and survival. There was no difference labeling either side of the shell. This study showed laser labeling is a relatively simple and practical marking method for mussels such as H. cumingii.