Total egg harvest by the calanoid copepod Acartia tonsa (Dana) in intensive culture – effects of high stocking densities on daily egg harvest and egg quality

Understanding the factors limiting copepod productivity in dense cultures is a prerequisite for the partial or entire replacement of Artemia and rotifers as live feed for finfish larvae. In dense cultures, high encounter rates between individuals may increase stress, cannibalism incidents and potentially trigger resting egg production. We conducted an experiment to evaluate the potential egg production and egg quality of Acartia tonsa stocked at densities ranging from 10 to >5000 ind. L⁻¹. Egg Production (EP), Delayed Hatching Eggs production (DHE), hatching success (HS), egg mortality and water quality were used as end points. In the present system, A. tonsa was raised at >5000 ind. L⁻¹ without affecting the mortality, confirming that attaining this high density in culture is possible. However, egg harvest reached an optimum of 12 000 egg L⁻¹ day⁻¹ at ~2500 ind. L⁻¹ indicating that increasing stocking density above this level is not of practical interest. Calculations showed that the loss in egg harvest at stocking densities