Ovarian maturation and spawning in the white shrimp, Penaeus vannamei, by serotonin injection

The effect of serotonin (5-hydroxytryptamine, 5-HT) injection on the ovarian maturation and spawning of wild Penaeus vannamei was investigated. The neurotransmitter was evaluated at 15 mu g g(-1) body weight (b.w.) and 50 mu g g(-1) b.w., applied at day 1, 11 and 21. The effect was compared against a control group, which received the injection of the sterile vehicle solution (NaCl 0.85%), and an unilaterally eyestalk ablated group. 5-HT induced ovarian maturation and spawning at both doses tested, generating more spawnings at 50 mu g g(-1) b.w.; however, unilateral eyestalk ablation induced a sooner and a higher rate of maturation and spawning. Our findings may be the result of 5-HT interaction with the release of different neurohormones and inhibition of methyl farnesoate synthesis. Additionally, gonad inhibiting hormone may have an intense control over ovaries and hepatopancreas. Spawnings obtained by serotonin treatment showed excellent quality, and it was not statistically different (P > 0.05) from unilaterally eyestalk ablated females. Further research is necessary in order to increase the spawning activity and define the duration of the reproductive performance of serotonin treated females. (C) 2000 Elsevier Science B.V. All rights reserved.