Induction of spawning and spermiation in captive Peruvian anchovy Engraulis ringens (Jennyns) using GnRH analogue injection

In order to achieve spawning in captive Engraulis ringens that would result in eggs and larvae for experimental assays, the present work evaluated the effect of buserelin acetate (an analogue of GnRH; GnRHa) injections on spawning and spermiation. Domperidone (DOM) was also used in order to reject a possible dopaminergic control in the release of endogenous gonadotropins for this species. Ripe fish were injected intraperitoneally with 0.005 μg GnRHa g^-1 fish (H), 0.005 μg GnRHa g^-1 fish + 0.01 mg DOM g^-1 fish (HD) or saline solution at 0.9% (SS). The GnRHa and GnRHa+DOM treatments showed an inductor effect on spawning, which occurred between 24 and 48 h post injection (p.i.). The results were significantly different (P < 0.05), with total percentages of 57.3% (GnRHa) and 20.9% (GnRHa+DOM). The effect of the hormone on spermiation was immediate, with the GnRHa (44.4%) treatment, and percentages of spermiated males at 0 hours p.i. differed significantly from the control (P < 0.05). Spermiation was highest 12 hours p.i., with values of 85.7% (GnRHa) and 75.0% (GnRHa+DOM). These values did not differ significantly (P > 0.05). Our results indicate the absence of a dopaminergic control in this species, since gametes were expelled with without domperidone. On the contrary, the percentages of spawned and spermiated fish after being injected with DOM were significantly lower.