THE KOREA-USA JOINT STUDY ON BAY ECOSYSTEM MODELLING
WITH OYSTERS
 
 

 THIS JOINT STUDY AIMS TO 

 
PARTICIPANTS INSTITUTION ADDRESS RESEARCH AREA
Dr. Pang, Ig-Chan Dept. Oceanography, Cheju Natl. Univ (CNU). 1 Ara 1 Dong, Cheju City, Cheju, 690-756  
Korea  
pangig@cheju.cheju.ac.kr		 Physical Oceangraphy
Dr. Lee, Joon-Baek Same Above jblee@cheju.cheju.ac.kr Phytoplankton Ecology and Taxonomy
Dr. Choi, Kwang-Sik Dept. Aquaculture, CNU skchoi@cheju.cheju.ac.kr  
http://shellfish.cheju.ac.kr		 Marine Biology and Physiology
Dr. Rho, Sum Dept. Aquaculture, CNU sumrho@cheju.cheju.ac.kr Fish Breeding and Aquaculture
Dr. Park, Kyung Dept. Oceanography,  
In-Ha Univeristy		 kpark@dragon.inha.ac.kr Physical Oceanography
Dr. Eric Powll Haskin Shellfish Research  
Laboratory		 eric@vertigo.hsrl.rutgers.edu  
http://www.hsrl.rutgers.edu		 Marine Ecology
Dr. Eileen Hofman Old Dominian University hofmann@ccpo.odu.edu  
http://www.ccpo.odu.edu		 Physical Oceanography
Dr. John Klinck Old Dominina University klinck@ccpo.odu.edu Physical Oceanography
 
 
OYSTERS used in this study :  Crassostrea gigas (Pacific oysters, "Cham-Gull")  
  • Kamakman Bay is a semi-closed Bay and famous for oyster culture.  In 1995,  a total of 191,156 metric tons of oysters are produced by aquaculture, and 20% of the total oyster yields are from Kamakman bay.  The Kamakman is also certified as "clean sea" for FDA of USA for oyster productions. Oysters prouduced from this bay is also exported to USA. 
  • The local government lease the oyster ground to the oyster growers, known as "liscence"  Each grower may get one to two hectar of the sea surface  as a oyster farm.  The growers also form a union, helping each other for oyster aquaculture. Two oyster grower unions are known in this area.  They are please to help us for the study of oyster ecology in this area.  All of the oysters produced in this bay are hanging culurture with lines (lan) of rope and rifters (buoys). 
  • Oysters in Kamakman spawn in late June to late August when seawater temperature reaches 20 to 25 C.  However, spats for the oyster farming are usually in short, not enough spats are collected for culture, they import the spats from other bays.
 

Bottom Topography of Kamakman Bay


 
 
  • Southcoast of Korea is strongly influenced by tidal current.  Tidal range in this area is known to be 3 m during springe tide.  Primary production in the bay is very high, very favorable for oyster culture.
  • In general, Kamakman Bay appears as a big lake; sea surface is very calm.  The bay has rich bottom fauna.  The bay is 15 km from north to south, 9 km from west to east, average depth of 9 m, and its volume is calculated to be 10.2 x 108 ton. 
  • Oysters and mussels (Mytilus edulis) are commercially raised in this bay, mostly oysters.  In 1993, a total of 100 oyster lease have been reported and the oyster production from this area accounts for 29% of total oyster production in Korea. 
 

OYSTER CULTURE GROUND IN KAMAKMAN BAY
 
  • In this Bay, oysters are hanging cultured with lans (lope) and buoys.  The oyster culture facility consists of two long lines which is 100m in length.  Those two lines are 40cm apart by buoys.  Each facility contains 20 buoys, 5m apart each.  Each end of the horizontal lines are anchored with 100 kg cement block. 
  • The local government lease the oyster culture ground to the oyster growers by hectar.  Each oyster lease contains 20 facilities (20 100m oyster hanging lines)
  • Oyster spats for culture are collected from elsewhere in this bay.  When not enough spats are collected, they purchase spats from other place.  To collect oyster spats, they use a 3 m long long-line (string).  Each long-line has 10 to 14 oyster shells inserted, "called  cluster".  Each cluster (oyster shells for the settlement of oyster larvae) is 30 cm apart. 
  • How many oysters in the oyster culture ground ?  There are 100 lease reported in 1993.  Each lease has 20 facilties.  Since each oyster string is 30cm apart and each facility has two 100 m horizontal lines for hanging oyster string, 300 x 2 = 600 oyster string/lease.  Each oyster string contains 10 oyster shells as spat colletor (cluster)  and may contain 12 oysters, therefore each string has 120 oysters. It is possible that each lease has 600 x 120 = 72,000 oysters.  Since there are 100 lease in Kamakman Bay, we can estimate 7,200,000 oysters in this bay in 1993.  However, this number is not fixed and varies year to year and season to season 
  • This photos shows the oyster hardening ground in Kamakman.  When oyster spats are collected using spat collector (right), they are transported to the hardening ground and the oysters are harden for 7 to 10 months.  This hardening process involves periodic exposure of oyster spats to atmosphere, simulating an intertidal environment. 
  • After hardening, oysters are transported to the main culture ground.  They are transplanted during late May to early June in this Bay
  • A fishmen is making oyster string with plastic line and oyster shells.  Each oyster string is 2.5 to 3 m long and  has 10 to 14 oyster shells as a spat collector.  Lee (1993) reports that each oyster shell in the oyster string (cluster) contains an averge of 20 oyster spats.  The survival rate of those spats vary year to year, an average of 60% indicating that 12 to 14 mature oysters are harvested. 
 

Oysters from Kamakman Bay
 
Oyster strings ; each of 3 m Crasssotrea gigas ; 10 month after hanging culture
 
Oyster cluster (cultch)
 
  • There are several species of marine organisms that compete with oysters for food and space.  Mytilus edulis is one of the competitor both for space and foods.  We have also observed that millions of caprallid amphipods from each oyster string.  It is possible that the amphipods also compete with oysters for foods.