Between 1996-2001, butyltin (BT) and phenyltin (PT) compounds were monitored in water, sediment, plankton mussels and fish from Otsuchi Bay. The changes of tributyltin (TBT) compounds in water and sediment were not observed during study period, however TBTs in plankton, mussels between 1997-1999 decreased in comparison with those in 1996. The current status of BTs and PTs in Otsuchi Bay was investigated. TBT in water, sediment, plankton, mussels and fish ranged of , 0.016-0.110mgkg^ dry, 0.010-0.255mgkg^ dry, 0.012-0.048mgkg^ wet and 0.009-0.029mgkg^ wet, respectively. TBT concentrations were high near the shipyard. Triphenyltin (TPT) compounds in water and mussel were not detected. TPT in sediment, plankton and fish ranged of dry, dry and wet, respectively
