Résumé
Flow-through planktonkreisels designed for lobster culture, consisting of circular 40-1 tanks with a hemispheric bottom, were modified for culture of
Cancer irroratus. The main modifications were: use of a 280-μm mesh screen around the overflow system; filtration of sea water to 50 μm during the development from zoeae 1 to zoeae 5; no filtration thereafter; flow-rate of 2.5–3 1 min
−1 during the development from zoeae 1 to early megalopa, then 1–1.5 1 min
−1 thereafter.
Under these conditions, survival rate to megalopa stage was 69%, yielding over 10 000 megalopae. Comparative experiments under static conditions, with addition of antibiotics, resulted in lower survival rate and absolute numbers of megalopae, and smaller size of zoeae and megalopae.
Modified planktronkreisels were well adapted to production of megalopae, but they failed to overcome the high rates of mortality that occur during the metamorphic transition from megalopae to the first crab stage. Maximum survival to crab stage was 12.7%. Future studies should address the need for an improved food and a tank design that will better serve the bottom-dwelling behaviour in the late megalopae.