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

“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

WaterT, S, DO

Sedimentsilt, organic %

Foodseston, 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 parameters Oyster parameters

Study period: late July to early December 2003Sampling frequency: every 2 to 4 weeks

Winter Monsoon started

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

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 assistantMs. Yeh Hsin-Yi

October 22, 2003