JOURNAL OF THE WORLD AQUACULTURE SOCIETY Vol. 42, No. 4 August, 2011 GnRHa-induced Multiple Spawns and Volition Spawning of Captive Spotted Rose Snapper, Lutjanus guttatus , at Mazatlan, Mexico Leonardo Ibarra-Castro and Luis Alvarez-Lajonch` ere 1,2 Centro de Investigaci´ on en Alimentaci´ on y Desarrollo, A. C., Avenida S´ abalo Cerritos S N, Mazatlan, C.P. 82010, A.P. 711, Sinaloa, Mexico Abstract. – Sexual maturation and induced spawning treatments were carried out with captive spotted rose snap- per, Lutjanus guttatus. A total of 3013 × 10 6 eggs (64.7% were floating) were produced from eight treated females in 42 spawns induced with GnRHa implants during the course of the present study. GnRHa ethylene-vinyl acetate copolymer effective doses were 204 ± 11 μg/kg in June 2005, and 224 ± 13 μg/kg in July 2005. General fertil- ization was 50.9 ± 34.5% and 12–14 h after spawning, viability of floating eggs was 90.4 ± 12.4%. Mean incuba- tion period at 29–31 C was 18–20 h, and mean hatching was 94.4 ± 8.2% (73–100%). Newly hatched larvae were 2.18 ± 0.15 mm in total length (TL). One month after the last hormone experiment, previously GnRHa-treated and untreated fish began spawning voluntarily. Hormone-treated breeders had higher fecundity than untreated fish, producing 72.5 million eggs versus 13.9 million eggs for the untreated fish, over the following 11 mo. Combined data of volitional spawning for total egg fertilization, viability, hatching, and larval TL were 77.7 ± 1.8%, 90.3 ± 1.3%, 87.9 ± 2%, and 2.50 ± 0.12 mm, respectively. These results can ensure the sustainability of a commercial hatchery. Snappers (Family Lutjanidae) are highly val- ued as food fishes and achieve high market prices worldwide. Several snapper species are commercially cultured in floating cages and coastal ponds, mostly in Asia, with a total pro- duction of 7302 t in 2007 (FAO 2010). Owing to current difficulties in spawning and rear- ing of snapper, much of this production is derived from the culture of snapper juveniles captured from the wild. The commercial pro- duction of any marine fish species-based wild juveniles can be unsustainable because the cap- ture of wild juveniles is unsustainable, limited, unpredictable, and costly. Therefore, a reliable, 1 Corresponding author. 2 Present address: Calle 41 No. 886, Nuevo Vedado, Plaza, La Habana, CP 10600, Cuba. cost-effective, and stable technology with con- sistent results for mass production of good qual- ity fry must be developed to meet growing demand and reduce pressure on wild popula- tions. The above goal has led to a general strat- egy for the establishment of captive broodstock of many marine fish species, as it is the basis of successful culture operations in many countries especially in Asia and the Mediterranean (Lee et al. 1993; Moretti et al. 1999). Spotted rose snapper, Lutjanus guttatus, is a popular food fish in several American countries with coasts on the Pacific Ocean. Studies on induced and natural reproduction of spotted rose snapper are currently underway in several Latin American countries to meet the growing need (Cano 2003; Boza-Abarca et al. 2008; Alvarez-Lajonch` ere et al. 2010; Herrera-Ulloa et al. 2010). Fattening of wild juveniles is growing in Sinaloa, Mexico, because of its local popularity and high market value. A spawning protocol using mature fish taken from the wild was developed by Ibarra-Castro and Duncan (2007), while previous efforts to establish a captive broodstock were not successful, although vitellogenesis was observed to start after a period of 8 mo in captivity (Ibarra- Castro et al. 2008). A very brief summary of some results of the induced spawning of captive fish was included by Ibarra-Castro and Alvarez-Lajonch` ere (2009). Spotted rose snapper is a batch spawner with asynchronous ovarian development, and a long reproductive season with two main spawning periods (Cruz- Romero et al. 1996). This article presents the methods and results of establishing a captive broodstock of the spotted rose snapper, as well © Copyright by the World Aquaculture Society 2011 564