Nursery and adult culture experiments of Tapes dorsatus in Beihai, Fangchenggang and Qinzhou sea areas

In order to explore the suitable breeding density and effective culture mode of Tapes dorsatus in three sea areas of Beibu Gulf, Guangxi, we had carried out basket nursery culture, basket adult culture and net cage hanging experiments of T. dorsatus in mudflat of three sea areas in Qingzhou, Beihai and Fangchenggang from May 2021 to January 2023. The results show that: 1) The suitable nursery culture density for T. dorsatus were 2 000, 1 500 and 1 500 grains·basket⁻¹, respectively, and the growth indexes and survival rate of T. dorsatus decreased with the increase of nursery culture density. The survival rates of all density groups in Beihai were significantly better than those in Fangchenggang and Qinzhou (P<0.05). Except that the growth indexes (Shell length, shell width and body mass) in d₅ group (3 000 grains·basket⁻¹) in Beihai were lower than that in Fangchenggang, the growth indexes of other groups were all higher than those of Fangchenggang and Qinzhou. 2) The suitable culture densities of T. dorsatus in Beihai, Fangchenggang and Qinzhou were 40, 40 and 20 grains·basket⁻¹, respectively. The growth indexes and survival rate of T. dorsatus at adult stage were Beihai>Fangchenggang>Qinzhou, and the survival rate decreased with the increase of cultivation density. When the density of net cage suspension in Fangchenggang was 30 grains· cage⁻¹, all growth indexes were the highest. There were no significant differences in shell length, shell width, shell height, body mass and survival rate among different density groups in net cage suspension (P>0.05). The results of environmental factors show that the water temperature, beach temperature, salinity, transparency, pH and DO in Beihai were slightly higher than those in Fangchenggang and Qinzhou, with relatively stable water quality. The water quality environment in Qinzhou and Fangchenggang changed greatly and was unstable. The diameter of plasmid at the bottom of Beihai mudflat was mainly coarse sand (49.00%), Fangchenggang was mainly composed of medium sand (59.28%), and Qinzhou was mainly composed of fine sand (77.33%). The results of phytoplankton quantity show that the species and quantity of phytoplankton algae in Beihai were the largest, and the least species and quantity of phytoplankton algae were in Qinzhou. The research indicates that T. dorsatus is suitable for nursery and adult culture in three sea areas of Beibu Gulf, and the breeding effect in Beihai is better than that in Fangchenggang and Qinzhou. Besides, 1.5-year-old T. dorsatus is suitable for net cage hanging culture in Fangchenggang sea area.