Invasive Species Compendium

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Abstract

Reproduction of ablated and unablated Penaeus schmitti in captivity using diets consisting of fresh-frozen natural and dried formulated feeds.

Abstract

Shrimps (Penaeus schmitti) were held in a recirculating seawater system and fed on a fresh-frozen diet of oysters, shrimps, worms and squid, a dry pelleted feed, containing 65% protein, 6% lipid and a mineral plus vitamin supplement, or an equal amount of the 2 diets. Shrimps fed on the mixed and dry diets had a higher (P<0.05) spawning rate (0.729 per day) than those given the fresh-frozen diet (0.446 per day). Ablation of one eyestalk increased the occurrence of female maturation on the mixed and fresh-frozen diets, by 245 and 548%, respectively, but did not influence spawn size or spawning frequency. Spawn size did not decline during the 2-month study, but spawn frequency and number of matings were reduced towards the end of the period. Diet influenced all reproductive processes monitored during the study. Dry feeding induced the best maturation, spawning and fecundity; results using the mixed diet were slightly lower, but did not differ significantly. Compared with the dry diet, the mixed and fresh-frozen diets induced higher (P<0.05) moulting (1.525 vs. 0.940 per tank of 40 shrimps per day) and mating (0.080 vs. 0 per tank per day) frequencies than the dried diet. Over all traits, it was concluded that the mixed diet led to the best results. The lunar cycle influenced moulting and mating; mating peaked during full and new moons, while moulting generally occurred between these periods.