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Toward the Sustainability of Oyster Toward the Sustainability of Oyster Aquaculture in Kinmen Island, TaiwanAquaculture in Kinmen Island, Taiwan
黃守忠、謝蕙蓮、陳章波黃守忠、謝蕙蓮、陳章波Shou-Chung HuangShou-Chung Huangaa, Hwey-Lian Hsieh, Hwey-Lian Hsiehaa, Chang-Po Chen, Chang-Po Chena,ba,b
a a Research Center for Biodiversity, Academia Sinica, Taipei, TResearch Center for Biodiversity, Academia Sinica, Taipei, Taiwanaiwan
b b Institute of Fisheries Sciences, National Taiwan University, TInstitute of Fisheries Sciences, National Taiwan University, Taipei, Taiwanaipei, Taiwan
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
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
WaterT, S, DO
Sedimentsilt, organic %
Foodseston, phytoplankton Parasites
flat warms, oyster drills
Disease
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 parameters Oyster parameters
Study period: late July to early December 2003Sampling frequency: every 2 to 4 weeks
Shuei-Tou Hu-Sia Bei-Shan
August -2.7% 9.0% -
September 9.2% 11.4% 4.4%
October 8.5% 12.3% 1.3%
November 7.1% 7.7% 2.2%
Monthly mortality rate
Shuei-Tou Hu-Sia Bei-Shan
August 16.2% 10.3% -
September 12.2% 9.9% 36.2%
October 1.7% -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
• Environmental monitoring– Pollution watch on Jiulong river
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!!!