Induction of spawning in gilthead seabream, Sparus aurata L., by a long-acting GnRH agonist and its effects on egg quality and daily timing of spawning

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

“…In the present study, increasing doses to higher than optimal doses (20, 30, 40 and 50 µg kg -1 ) resulted in a gradual reduction in latency period, fecundity and egg quality, fertilisation, percentage of viable eggs and percentage hatch. Studies on other species have also found that higher than optimal doses resulted in a shorter latency period (Wang et al, 2009), decreased fecundity (Garcia, 1989;Ibarra & Duncan, 2007) and decreased egg quality, percentage hatch (Garcia, 1989;Taranger et al, 1992;Ibarra & Duncan, 2007), fertilisation (Garcia, 1989;Taranger et al, 1992) and percentage of viable eggs (Barbaro et al, 1997). The present study appears to confirm that oocyte maturation was accelerated by the administration of GnRHa in a dose-dependent way.…”

“…In the present study, reducing the dose from the optimal dose (15 µg kg -1 ) to lower than optimal doses (0, 1, 5 and 10 µg kg -1 ) exhibited a gradual increase in latency period and decrease in fecundity and egg quality, fertilisation, percentage of viable eggs and percentage hatch. Studies on other species have also found that lower than optimal doses resulted in longer latency period (Yang & Chen, 2004;Wang et al, 2009), decreased fecundity (Garcia, 1989;Barbaro et al, 1997;Ibarra & Duncan, 2007) and decreased percentage hatch (Ibarra & Duncan, 2007). In the present study, increasing doses to higher than optimal doses (20, 30, 40 and 50 µg kg -1 ) resulted in a gradual reduction in latency period, fecundity and egg quality, fertilisation, percentage of viable eggs and percentage hatch.…”

“…Optimal GnRHa doses have also been found in similar studies on sea bass (Lates calcarifer) (Garcia, 1989), gilthead seabream (Sparus aurata) (Barbaro et al, 1997) and spotted rose snapper (Lutjanus guttatus) (Ibarra & Duncan, 2007). It has been demonstrated that GnRHa stimulates spawning in fish with arrested maturation by releasing LH from the pituitary, which in turn stimulates oocyte maturation and the fish to spawn (Zohar et al, 1995;Mañanos et al, 2002;Podhorec et al, 2012).…”

“…It has been demonstrated that GnRHa stimulates spawning in fish with arrested maturation by releasing LH from the pituitary, which in turn stimulates oocyte maturation and the fish to spawn (Zohar et al, 1995;Mañanos et al, 2002;Podhorec et al, 2012). Increasing doses (1-20 µg kg -1 ) of mammalian gonadotrophin-releasing hormone agonists, mGnRHa ([DAla 6 , Pro 9 , NEthylamide]-mGnRH) were positively correlated to levels of circulating LH and ovulation rate in tench (Tinca tinca) (Podhorec et al, 2011) and high GnRHa doses have been described to accelerate oocyte development (Mylonas et al, 1992;Barbaro et al, 1997;Mugnier et al, 2000;Duncan et al, 2003). In the present study latency time from the application of GnRHa to the time eggs were collected decreased linearly (R 2 = 0.93) and demonstrated an accelerating effect of an increasing GnRHa dose.…”

Mating behaviour and gamete release in gilthead seabream (Sparus aurata, Linnaeus 1758) held in captivity

“…Gilthead seabream is a protandrous hermaphrodite species with an asynchronous ovarian development (Zohar et al, 1995). Broodstock held in captivity under natural conditions typically start vitellogenesis in September-November, spawning begins during December-January and lasts for 3-5 months with daily spawning, leading to an annual fecundity of 2,000,000 eggs/kg (diameter<1 mm) with a fertilization rate of 80-85% (Barbaro et al, 1997;Arabaci et al, 2010;Mylonas et al, 2011). However, the reproductive behaviour of gilthead seabream has not been reported, despite an increasing need to understand the factors that influence a breeders participation in spawning in order to control the families produced from a broodstock (Gorshkov et al, 1997;Brown et al, 2005;Porta et al, 2009;Chavanne et al, 2012).…”