Salinity responses of the juvenile penaeid shrimp Penaeus japonicus: I. Oxygen consumption and estimations of productivity

The oxygen consumption of Penaeus japonicus was measured in relation to low salinity stress and crowding. Within 48 h, Penaeus japonicus shows no mortality in a salinity range of 25–40‰ and a mortality of only 25–30% within a salinity range of 10–55‰. With a change in salinity from 37‰ to 10‰, oxygen consumption increases rapidly to 300% of the initial value and stabilizes at 200% after a few hours. After the initial conditions are restored, oxygen consumption remains raised for at least 6 h. The calculated loss of productivity caused by a reduction of salinity can amount to 33% of total animal weight. Crowding also increases oxygen consumption at a stocking density above 400 postlarval prawns/m². In consequence, a stable environmental salinity range of 30–40‰ and low stocking densities are recommended for extensive aquaculture.