Improved hatchery-rearing techniques for juvenile production of blue swimming crab, Portunus pelagicus (Linnaeus, 1758)

Abstract

The effects of tank colour, larval stocking density, antibiotic administration and water exchange on survival and moulting of blue swimming crab, Portunus pelagicus, were determined. Circular 4-m 3 experimental larval-rearing tanks were used in triplicate for all treatments. White, dark grey, blue and brown were tested as tank background colours. The stocking densities tested were 10, 20, 40, 60, 80 and 100 larvae L À1 . The effect of oxytetracycline was estimated by comparing a treatment with oxytetracycline to a treatment without oxytetracycline administration. The daily water exchange rates tested were 0%, 25%, 50% and 100% of the tank volume. In all treatments, the larvae were fed with Artemia nauplii, rotifers and encapsulated Spirulina. The highest percentage survival was observed in the dark-grey tanks when the stocking density of larvae was 20 larvae L À1 .No larva reached the juvenile crab size in white tanks. No significant difference in survival was found between treated and non-treated larvae with oxytetracycline when the daily water exchange rate was more than 50%.

Systems and techniques used in the culture of soft‐shell swimming crabs

“…However, methods of obtaining swimming crabs are directly dependent on natural stocks which, in turn, are vulnerable to pressure from overfishing, pollution or climate changes. Different combinations of these factors have been responsible for the decline of populations in recent years in many regions of the globe (Lindner 2005;Paolisso 2007;Shelley 2008;Zohar et al 2008;Johnston et al 2011;Shelley & Lovatelli 2011;Ikhwanuddin et al 2012).…”

Impact of tank background on the welfare of the African clawed frog, Xenopus laevis (Daudin)

“…Sherwin and Glen, 2003;Rahnama et al, 2015), immunosuppression (Eslamloo et al, 2015), mortality (e.g. El-Sayed and El-Ghobashy, 2011;Sykes et al, 2011;Ikhwanuddin et al, 2012), and behaviour (e.g. Höglund et al, 2002;Cobcroft et al, 2012) in a range of taxa.…”

“…Downing and Litvak, 1999;Karakatsouli et al, 2015) and crustaceans (e.g. Ikhwanuddin et al, 2012;Maciel and Valenti, 2014). Research investigating the effect of background colour on amphibians is more limited, despite crypsis camouflage requirements being important for species that exhibit a background choice (Jonnalagadda et al, 1993;Garcia and Sih, 2003;Wente and Phillips, 2005) or alter their skin colour to match the background (Garcia and Sih, 2003;Segev, 2009).…”

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“…Some efforts have been made to identify the factors, which can be manipulated in laboratories such as tank colour, stocking density, antibiotic administration and water exchange. However, only some of them have been found to improve the survival such as dark tank color (Ikhwanuddin, Monsoor, Bolong & Long, 2012), stocking density, artificial foods and feed supplements (Heasman & Felder, 1983;Williams, Wood, Dalliston, Shelley, & Kuo, 1999;Hamasaki, Suprayudi & Takeuchi, 2002;Mann, Asakawa, Kelly, Lindsay & Paterson, 2007). The present experiment was an attempt towards developing a reliable nursing system such as the use of Cups and application of supplements e.g.…”