Environmental capacity of cultured scallop in Ogatsu Bay

Representative Organization: Tohoku University

2013/12/01 - 2013/12/31
once a year

Two stations of Ogatsu Bay (St 1 & 2)

Field survey

The growth condition is calculated as a production per line based on the number of facility and annual production in the bay and compared to pre-quake level. In parallel with it the scallops cultured by ear hang method at two stations of Ogatsu Bay are also used for another estimation of growth condition. Shell size, weight of softbody and indicates of each organ is evaluated and compared to pre-quake level. The environmental capacity for scallop culture in Ogatsu Bay is considered by growth condition and food availability based on a primary production.

The number of facility for scallop culture recovered to about 40% and the annual production of the cultured scallop recovered to about 70% in the Ogatsu Bay before the earthquake disaster in fiscal 2013. To evaluate productivity of scallop in the Ogatsu Bay the production of each rope by which scallops are ear-hung was calculated. In fiscal 2013 the productivity of each rope showed higher level of 31 kg than the pre-quake level of 20 kg. Chlorophyll a concentration varied within anrange from 0.3 to 15.0 ug/L throughout the year, which is the same fluctuation as past. The poor growth in shell size of scallop cultured in deeper layer found before earthquake was not observed and the adductor muscle index (adductor muscle weight/whole soft body weight*100) showed a higher value of 35 in both layers compared with pre-quake level of 30. These results suggest that a food availability for good growth of scallop is guaranteed in the Ogatsu Bay at the moment and the scallop calture in the Ogatsu Bay is conducted under environmental carrying capacity.

FY2013 Environmental capacity of cultured scallop in Ogatsu Bay