Detailed Explanation of Key Points in Sea Cucumber Breeding and Seedling Rearing Technology

Seedling rearing process flow

Collection and keeping of parent sea cucumbers→artificial spawning induction and insemination→fertilized egg incubation and larval selection and breeding→rearing management (controlling a reasonable rearing density, water exchange and water quality management, suitable feed and feeding, production and placement of attachment devices)→juvenile sea cucumber rearing.

Feed

Feed should be given immediately after the larvae are selected into the pond. Feeding sufficient and suitable feed is the prerequisite for normal growth, development and smooth metamorphosis of the larvae. Suitable feeds include Dunaliella salina, Dicrateria zhanjiangensis, Chaetoceros muelleri, Phaeodactylum tricornutum and Nitzschia closterium f. minutissima. Feeding these feeds alone or in combination can achieve good rearing results. However, feeding a mixture of 2-3 kinds of feed gives better results, as mixed feeding can provide complementary nutrition and meet the nutritional needs of the larvae. For the first 3 days, the feeding amount can be 15,000-20,000 cells/ml, and thereafter 30,000 cells/ml. If the feed is insufficient, 0.5 ppm yeast powder supernatant can be added. Although Platymonas and Heterogloea have a certain feed effect, they are not suitable as feed during the larval stage of Apostichopus japonicus. When the larvae metamorphose into doliolaria larvae, in order to fully utilize the water body and increase the attachment area, and because of the change in feeding habits, suitable attachment materials should be placed at this time. Benthic diatoms are inoculated onto the attachment materials assembled from corrugated plates. About 10 days before use, the attached benthic diatoms should be brushed off, repeatedly filtered again with N×103 mesh silk, removing large algae and aged algae, and then inoculated again, so that a thin layer of benthic diatoms is evenly reattached to the plates for early consumption by juvenile sea cucumbers.

Disease prevention and control

To strengthen the reproduction of benthic diatoms, lighting can be appropriately adjusted, but the light intensity should be controlled at about 1000 lux; too strong light easily grows green algae and Oscillatoria. During the culture period, weak aeration should be provided. To effectively kill copepods, copepods should be killed in advance before the attachment devices are placed, and after the attachment plates are put into the pond, medication should be applied once every 7-10 days. During the high water temperature period (above 20°C), after daily water exchange, 1-3 ppm antibiotics should be applied alternately to prevent disease occurrence.