1. Toward the Sustainability of Oyster Aquaculture in Kinmen Island, Taiwan 黃守忠、謝蕙蓮、陳章波 Shou-Chung Huang a, Hwey-Lian Hsieh a, Chang-Po Chen a,b a Research Center for Biodiversity, Academia Sinica, Taipei, Taiwan b Institute of Fisheries Sciences, National Taiwan University, Taipei, Taiwan

2. Outlines Oyster cultures in Kinmen: “Rock oysters” vs. “Hanging oysters” A research project in 2003 -Background -methods -results -conclusions Suggestions for sustainable oyster aquaculture in Kinmen

3. “Rock oysters”

4. “Hanging oysters”

5. Rock oysters Hanging oysters

6. Background Production declines in the past two decades. –1982: 1255 tons –1992: 521 tons –2002: 227 tons Fishermen reported mass mortality in summer and fall in recent years.

7. Questions Did mass mortality really occur? What factors affect oyster’s growth & mortality? Oysters Water T, S, DO Sediment silt, organic % Food seston, phytoplankton Parasites flat warms, oyster drills Disease

8. Study sites 北山 湖下 水頭

9. Approaches Temperature Salinity DO Seston (~= SS) Chlorophyll a Particulate organic carbon Particulate organic nitrogen Shell length Mortality ratio Condition index (CI) Respiration rate Excretion rate Environmental parametersOyster parameters Study period: late July to early December 2003 Sampling frequency: every 2 to 4 weeks

15. Winter Monsoon started

19. Shuei-TouHu-SiaBei-Shan August-2.7%9.0%- September9.2%11.4%4.4% October8.5%12.3%1.3% November7.1%7.7%2.2% Monthly mortality rate

20. Shuei-TouHu-SiaBei-Shan August16.2%10.3%- September12.2%9.9%36.2% October1.7%-0.1%10.5% November---1.0% Monthly growth rate

22. Conclusions Winter monsoon started in late September and resulted in poor growing environments for oysters in Kinmen. Mass mortality did not occur, but conditions of hanging oysters began to deteriorate in October, right after winter Monsoon started. Rock oysters performed better than hanging oysters with lower mortality and higher growth rates during winter Monsoon season. The poor adaptation of hanging oysters was resulted,we hypothesized, from importing their spats from southwest coasts of Taiwan.

23. Suggestions Active management –Adjusting rearing and harvest time –Rotation of culture locations

25. Suggestions Active management –Adjusting rearing and harvest time –Rotation of culture locations Environmental monitoring –Pollution watch on Jiulong river

26. Jiulong River Xiamen Kinmen

27. Suggestions Active management –Adjusting rearing and harvest time –Rotation of culture locations Environmental monitoring –Pollution watch on Jiulong river Improve marketing, esp. the rock oysters Open oyster farms for tours Need more studies!!!

28. Thank you & a major help from our research assistant Ms. Yeh Hsin-Yi

30. October 22, 2003