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Larval culture of Atlantic cod (Gadus morhua) at high stocking densities

Baskerville-Bridges, B., Kling, L.J.
Aquaculture 2000 no.1/2 pp. 61-69
Gadus morhua, fish culture, larvae, stocking rate, mortality, feed rations, fish feeding, length, weight, water quality, rearing, intensive forestry
Experiments were conducted to investigate the growth and survival of Atlantic cod (Gadus morhua) larvae at high stocking densities. The larvae were reared in replicated 221 tanks that were part of a 7500-l recirculating system. Survival through day 44 was 41.6% +/- 1.9 (Mean +/- SE) at 300 larvae/l, which verifies that they can be reared at high densities. However, lower growth rates were experienced at 300 larvae/l than at 150 larvae/l as food appeared to be a limiting factor at the higher density. As a result, a second experiment was performed where cod larvae were reared at 50, 100, 200, and 300 larvae/l and food was not limiting. No differences were observed in survival, length or dry weight among the four treatments through 36 days post-hatch (dph). High stocking density also had no effect on specific growth rate, supporting the proposition that food was a limiting factor in the earlier trial. However, there is greater risk of mortality at high stocking densities as a result of deteriorating water quality. In the light of these findings, optimal stocking densities need to be reexamined under commercial culture conditions.