A new tagging method and its early stress effect on the sea cucumber Apostichopus japonicus

The sea cucumber Apostichopus japonicus is a widely exploited species that is highly valued as a traditional medicine and as a food product in China, Singapore, Japan and many other countries of Southeast Asia. With the fast development of sea cucumber fisheries and aquaculture, in-situ investigation is necessary to assess the stock amount, growth and migration of cultured sea cucumbers. Unfortunately, this work is limited for the lacking of effective tagging method for the species. In this study, a calcareous-ring-threading method (CRT method) was tried to tag the sea cucumber A. japonicus. The early stress response of the sea cucumber to tagging operation and invasive tag was monitored so as to evaluate the reliability of the new method. This method had a tag retention rate of 84%, which was higher than the T-bar method (65%), during a 1-month experiment. The results showed that the side effects on large individuals (wet weight above 40 g) disappeared after 2 days. The individuals with a wet weight below 40 g had less tolerance on the new tagging method and couldn't recover after 7 days. It is feasible to select large A. japonicus individuals with a wet weight above 60 g for this new tagging method. Based on the result of present study, the CRT method is considered to be applicable for tagging A. japonicus individuals with wet weights above 60 g.