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

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

“Rock oysters”

“Hanging oysters”

Rock oysters Hanging oysters

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.

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

Study sites 北山 湖下 水頭

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

Winter Monsoon started

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

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

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.

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

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

Jiulong River Xiamen Kinmen

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!!!

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

October 22, 2003