Gonad maturation in Octopus vulgaris during ongrowing, under different conditions of sex ratio

Abstract

Estefanell, J., Socorro, J., Roo, F. J., Fernández-Palacios, H., and Izquierdo, M. 2010. Gonad maturation in Octopus vulgaris during ongrowing, under different conditions of sex ratio. – ICES Journal of Marine Science, 67: 1487–1493. Octopus vulgaris is a suitable candidate for aquaculture, but there are problems with breeding in captivity, such as aggressive behaviour among males and the frequent death of females after the eggs hatch. To avoid these problems and further understand the sexual maturation of common octopus in captivity, males and females were reared together and separately under similar culture conditions. In all trials, the initial rearing density was 10 kg m−3. Females (n = 15, sex ratio 0:1) and males (n = 11, sex ratio 1:0) were kept in circular tanks, and a mixed group (n = 209, sex ratio 4:1) in floating cages. Trials started in November 2008 and octopuses from each treatment were examined macroscopically and histologically in December and January to assess sexual maturation. All the males matured, regardless of the sex ratio during rearing, as did all females in the mixed group. In contrast, a large proportion of the females kept isolated from males was still immature in December and January. Although maturation was successful in floating cages, there was 76% mortality there, in contrast to the zero mortality in tanks. Moreover, most of the dead octopuses from the cages were in post-reproductive condition, with a low digestive gland index, suggesting that this was natural post-reproductive mortality. Therefore, sex segregation is deemed advantageous to avoiding early mortality.

Comparison Between Individual and Group Rearing Systems in Octopus vulgaris (Cuvier, 1797)

“…Prior to the beginning of this trial, males and females were separated upon arrival to our facilities, so sexual interaction probably occurred in nature or most likely in the trawl, where octopus may be kept for a few days until transport to lab facilities. Also, low DGI in comparison with octopus reared in Trial 1 is related to poor condition (Cerezo Valverde et al 2008; Estefanell et al 2010).…”

“…Particularly in Trial 1, low growth rates observed in females and the presence of egg masses evidenced reproductive behavior (Iglesias et al 2000), which is associated to the end of O. vulgaris life cycle in both sexes (Estefanell et al 2010). Also, different growth rate and final weight between sexes led to high weight dispersion, which also increases mortality in O. vulgaris under rearing conditions, due to hierarchical behavior and cannibalism (Socorro et al 2005; García García et al 2009).…”

“…Indeed, octopus industrial farming is carried out in floating cages provided with shelters (Chapela et al 2006; Rodríguez et al 2006). Particularly in O. vulgaris , mortality under rearing conditions is associated to hierarchical behavior, cannibalism, and reproductive processes (García García et al 2009; Estefanell et al 2010). In contrast, high survival rates were observed in octopuses reared in confinement in individual tanks (Petza et al 2006; García García and Cerezo Valverde 2006; Miliou et al 2007; García Garrido et al 2011) or in individual net cages placed inside tanks (400–1000 L) (Biandolino et al 2010; Estefanell et al 2009; Prato et al 2010).…”

Identification of a Δ5-like Fatty Acyl Desaturase from the Cephalopod Octopus vulgaris (Cuvier 1797) Involved in the Biosynthesis of Essential Fatty Acids

“…The common octopus (Octopus vulgaris, Cuvier 1797) is a prime candidate for diversification of marine aquaculture, and extensive research efforts have been devoted over the last decade to investigate several aspects of octopus culture including husbandry (Iglesias et al 2006), reproduction (Estefanell et al 2010;Otero et al 2007;Wodinsky 2008) and nutrition Villanueva 2000, 2003;Quintana 2009;Villanueva et al 2009). Although considerable progress has been made and on-growing wild-captured octopus in floating cages is now possible (Iglesias et al 2007), a major, yet unresolved, problem in octopus culture is the high mortality of paralarvae, early pelagic life stages, which massively die during metamorphosis to benthic life stages, and consequently, the octopus life cycle in captivity has not yet been closed.…”

Biological performance ofOctopus vulgarisin ‘integrated aquaculture’ models: effect of two potential fresh diets, sex and sexual maturation during the grow-out phase

“…Increased mortality associated with reproductive processes has been observed under rearing conditions in both sexes (Estefanell et al . ). In contrast, several authors reported a high biological performance in males and females of O. vulgaris reared together in floating cages (Rodríguez et al .…”