Shelters for aquaculture of Octopus sinensis: preferences for gap width and horizontal versus vertical plates

Abstract

It is difficult to keep a large number of cultured octopuses together in the same holding tank due to the high incidence of cannibalism. Appropriate shelters within which the octopuses can more readily avoid their peers are expected to ameliorate this problem. Shelters can be constructed from square plates assembled with appropriate spacing (gap) between them. The purpose of this study was to ascertain the optimum plate orientation and gap width between plates for shelters to maximize the accommodation of octopuses. It was found that the number of shelter occupants increased with the number of gaps available, such that more than half of the individuals in the experimental tank used the same shelter simultaneously. Octopuses tested singly to determine preferences for shelters placed vertically or horizontally preferred the vertical arrangement. Octopuses of more than 300 g tested singly in aquaria given shelters with different gap widths (20–100 mm) were found to not enter shelters with gap widths of 20 or 40 mm. It is concluded that octopus shelters constructed from square vertical plates spaced with gap widths suitable for octopuses are a useful contribution towards maximizing the number of octopuses that can be maintained in culture conditions.

Evaluation ofOctopus mayaenzyme activity of the digestive gland and gastric juice

“…To design and develop formulated feed for cephalopods, understanding their digestive physiology is essential. Given the carnivorous feeding habits of octopuses, proteolytic enzymes play a key role in their digestive process; among them are trypsin and chymotrypsin, both from salivary (García-Garrido et al, 2016; Grisley et al, 1996; Morishita et al, 1974; Omedes et al, 2022; Suzumura et al, 2023) and digestive glands, which are the most widely studied enzymes in cephalopods (Mancuso et al, 2014; Martínez et al, 2011; Martínez et al, 2012; Pereda et al, 2009; Rosas et al, 2011). In comparison to proteases, studies on carbohydrases and lipases in cephalopods are limited to Octopus cyanea (Boucher-Rodoni, 1973; Omedes et al, 2022), Eledone cirrosa (Boucher, 1975), O. vulgaris (Boucher-Rodoni and Boucaud-Camou, 1987; O’dor et al, 1984), Octopus maya (Aguila et al, 2007; Gallardo et al, 2017; Moguel et al, 2010), O. bimaculoides (Ibarra-García et al, 2018; Solorzano et al, 2009) and O. mimus (Linares et al, 2015).…”

The effectiveness and impact of disinfection with chlorine on embryos and early hatchlings of two Western Pacific octopus species

“…Amphioctopus fangsiao is a holobenthic octopus with a maximum size <200 g and produces small egg clutches of a few hundred embryos, which develop directly into juveniles (Jereb et al, 2014; Jiang et al, 2020a; Pang et al, 2020). Octopus sinensis is a medium‐sized merobenthic octopus that can reach over 3000 g and produces large egg clutches of up to 500,000 embryos, which have an indirect development from paralarvae through a settlement stage before they become fully benthic juveniles (Jereb et al, 2014; Joll, 1976; Mangold, 1983; Suzumura et al, 2022). Recent decline in annual catches for both species because of overfished wild stocks has stimulated research on various aspects of their biology, habitat requirements, reproduction, and commercial culture (Cai et al, 2007; Dan et al, 2019; Hamasaki et al, 1991; Hamasaki & Takeuchi, 2001; Jiang et al, 2020a, 2020b; Pang et al, 2020; Tziouveli & Yokoyama, 2017; Zheng et al, 2023).…”