Dose-dependent effect of a single GnRHa injection on the spawning of meagre (Argyrosomus regius) broodstock reared in captivity

Abstract

Abbreviations used: EVAc (ethylene vinyl acetate); GnRHa (gonadotrophin-releasing hormone agonists); LH (luteinizing hormone); mGnRHa (mammalian gonadotrophin-releasing hormone agonists); PIT (passive integrated transponder).

Reproduction of hatchery-produced meagre Argyrosomus regius in captivity III. Comparison between GnRHa implants and injections on spawning kinetics and egg/larval performance parameters

“…In general, however, results indicated that the produced egg quality and larval survival remained high in response to subsequent injections, or even improved slightly. The present results are in complete agreement with a recent work examining the dose-dependent effect of GnRHa injections on the spawning of meagre (Fernández-Palacios et al, 2014). In that study, up to nine consecutive weekly injections of GnRHa were used, resulting in a maximum of two spawns per injection, with a fecundity ranging between~98,000 and 247,000 eggs kg −1 injection −1 , which is very similar to the fecundities obtained here.…”

“…In that study, up to nine consecutive weekly injections of GnRHa were used, resulting in a maximum of two spawns per injection, with a fecundity ranging between~98,000 and 247,000 eggs kg −1 injection −1 , which is very similar to the fecundities obtained here. The higher fecundity values from the study of Fernández-Palacios et al (2014) were obtained with a dose of 15 μg kg −1 GnRHa, which is similar to the doses used here (15-25 μg kg −1 GnRHa). Fertilization, hatching and larval survival were also very similar between the two studies.…”

“…Experiments with GnRHa treatments were effective in inducing maturation of both wildcaught (Duncan et al, 2012) and hatchery-produced broodstocks (Fernández-Palacios et al, 2014;Mylonas et al, 2013a). Both liquid injections and controlled-release delivery systems (implants) that release GnRHa for a prolonged period of time have been shown to be effective in inducing maturation in females (Duncan et al, 2012(Duncan et al, , 2013Fernández-Palacios et al, 2014;Mylonas et al, 2013a).…”

“…Experiments with GnRHa treatments were effective in inducing maturation of both wildcaught (Duncan et al, 2012) and hatchery-produced broodstocks (Fernández-Palacios et al, 2014;Mylonas et al, 2013a). Both liquid injections and controlled-release delivery systems (implants) that release GnRHa for a prolonged period of time have been shown to be effective in inducing maturation in females (Duncan et al, 2012(Duncan et al, , 2013Fernández-Palacios et al, 2014;Mylonas et al, 2013a). In the case of a single injection of GnRHa, lower total fecundity was obtained due to the fact that a GnRHa injection induced only 2-3 spawns (Duncan et al, 2012(Duncan et al, , 2013Fernández-Palacios et al, 2014), while the species has the capacity for multiple spawns (Gil et al, 2013;Mylonas et al, 2013b).…”

“…Both liquid injections and controlled-release delivery systems (implants) that release GnRHa for a prolonged period of time have been shown to be effective in inducing maturation in females (Duncan et al, 2012(Duncan et al, , 2013Fernández-Palacios et al, 2014;Mylonas et al, 2013a). In the case of a single injection of GnRHa, lower total fecundity was obtained due to the fact that a GnRHa injection induced only 2-3 spawns (Duncan et al, 2012(Duncan et al, , 2013Fernández-Palacios et al, 2014), while the species has the capacity for multiple spawns (Gil et al, 2013;Mylonas et al, 2013b). On the other hand, GnRHa implants produce multiple daily spawns (Mylonas et al, 2013a), as described in various other fishes with a protracted spawning season and asynchronous or group synchronous ovarian development, which undergo many cycles of oocyte maturation in the course of many weeks (Guzmán et al, 2009;Kokokiris et al, 2005;Larsson et al, 1997;Zohar et al, 1995).…”