Zoological Studies

Vol. 60, 2021

(update: 2021.06.18; 09.07)
 

Reproduction and Early Juvenile Growth of the Giant Clams Tridacna noae and Tridacna maxima in Taiwan

Po-Wei Su1, Gwo-Liang Zhang2,*, Bonien Chen3, Keryea Soong4, and Li-Lian Liu4,5,*

doi:10.6620/ZS.2021.60-49

1Fisheries Agency, Council of Agriculture, Executive Yuan, Taipei, Taiwan. E-mail: c7921640@gmail.com (Su)
2Department of Aquaculture, National Penghu University of Science and Technology, Penghu 880, Taiwan. *Correspondence: E-mail: c5875yo@gmail.com (Zhang)
3Department of Aquaculture, National Kaohsiung University of Science and Technology, Kaohsiung 811, Taiwan. E-mail: cbnabalone@gmail.com (Chen)
4Department of Oceanography, National Sun Yat-sen University, Kaohsiung 804, Taiwan. *Correspondence: E-mail: lilian@mail.nsysu.edu.tw (Liu). E-mail: keryea@mail.nsysu.edu.tw (Soong)
5NSYSU Frontier Center for Ocean Science and Technology, National Sun Yat-sen University, Taiwan, Kaohsiung 804, Taiwan.

Received 29 June 2020 / Accepted 31 May 2021
Communicated by Benny K.K. Chan

The reproductive cycle, larval development, and juvenile growth of Tridacna noae and Tridacna maxima were investigated to improve their hatchery production for conservation and commercial use in Taiwan. To study the giant clam reproductive cycle, hypodermic extraction of oocytes from T. noae and T. maxima was conducted in Dongsha and Kenting, Taiwan, from March 2013 to May 2014; ripe eggs were observed in both species from March to August. There was no apparent correlation between reproduction and water temperature. Artificial fertilization was successfully conducted in T. maxima, T. noae, and a hybrid of T. maxima♀/T. noae♂. The diameter of fertilized eggs was 99.0 ?8.1, 113.8 ?18.5, and 116.3 ?6.2 μm, respectively. On day 6, the hybrid died. Tridacna maxima grew more than T. noae in both 1- and 10-month-old juveniles. The juvenilegrowth of T. noae was compared between the artificial breeding sites of Penghu and Linbian, which represent the main ornamental aquatic animal culture areas of Taiwan. Starting with individuals with a shell length of 15.9 ?2.5 mm (265 days old), the juveniles observed in Linbian were significantly larger than those in Penghu, i.e., 26.6 ?3.6 mm on day 307 vs. 18.6 ?2.9 mm on day 321 (p < 0.001). This might be linked to the differences in local water temperatures between the two locations, i.e., 20.3–27.0oC vs. 16.9–23.9oC, respectively. These results can be used to further research ways to maximize spat production and minimize giant clam operational costs.

Key words: Reproductive cycle, Hybrid, Larval development, Temperature, Dongsha, Kenting.

Citation: Su PW, Zhang GL, Chen PN, Soong K, Liu LL. 2021. Reproduction and Early Juvenile Growth of the Giant Clams Tridacna noae and Tridacna maxima in Taiwan. Zool Stud 60:49. doi:10.6620/ZS.2021.60-49.