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

The effect of serotonin (5-hydroxytryptamine, 5-HT) injection on the ovaria n maturation and spawning of wild Penaeus vannamei was investigated. The ne urotransmitter 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 soluti on (NaCl 0.85%), and an unilaterally eyestalk ablated group. 5-HT induced o varian maturation and spawning at both doses tested, generating more spawni ngs 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 th e result of 5-HT interaction with the release of different neurohormones an d inhibition of methyl farnesoate synthesis. Additionally, gonad inhibiting hormone may have an intense control over ovaries and hepatopancreas. Spawn ings obtained by serotonin treatment showed excellent quality, and it was n ot statistically different (P > 0.05) from unilaterally eyestalk ablated fe males. Further research is necessary in order to increase the spawning acti vity and define the duration of the reproductive performance of serotonin t reated females. (C) 2000 Elsevier Science B.V. All rights reserved.