Evaluation of different induced molting methods in Callinectes ornatus (Crustacea, Decapoda, Portunidae) as a tool for the commercial production of soft-shell crabs.

Camila P.S Tavares,Antonio Ostrensky,Leandro Ângelo Pereira,Ubiratã A.T Da Silva

doi:10.1590/0001-3765202120190580

Abstract

We investigated the effects of eyestalk ablation and cheliped autotomy in inducing molting in Callinectes ornatus. The specimens in intermolt stage were divided into two size classes: 1 (30-50 mm) and 2 (51-70 mm) and were further divided into four experimental groups. In the CA group (Cheliped Autotomy, n=76), crabs were submitted to cheliped autotomy; in the UA group (Unilateral Ablation, n=66) and BA group (Bilateral Ablation, n=66) to unilateral and bilateral eyestalk ablation, respectively. The C group (Control, n=70) was used as control. The animals were individually kept in tanks interconnected to a recirculation system for 30 days. The highest frequency of premolt was recorded in the BA group (32%), followed by the CA group (16%). The premolt frequency of class 1 (28%) was significantly higher (p<0.05) than of class 2 (8%). The mean time until molt in the BA group was significantly lower (p <0.05) than other groups tested. The highest mortality rates were 55% and 25% in crabs from the BA and CA groups, respectively. The results indicate bilateral eyestalk ablation and cheliped autotomy are potentially capable of inducing molt in C. ornatus, but these techniques have limited efficiency for the commercial application of large-scale soft-shell crab.

Highlights

The Portunidae family, composed of crustaceans popularly known as swimming crab, is characterized by the presence of morphological adaptations that allow them to explore the water column
As a way to fill this gap in the literature, this study aimed to test three techniques of molt induction in Callinectes ornatus, to evaluate their efficacy and effect on mortality rates of
The crabs were protected by plastic screens, to minimize mortality during transport to the Centro de Aquicultura Marinha e Repovoamento (CAMAR), belonging to the Grupo Integrado de Aquicultura e Estudos Ambientais (GIA), from the Universidade Federal do Paraná (UFPR), located 10 km from the fishing site (25°41’29.94”S/48°27’57.09”W)

Summary

Introduction

The Portunidae family, composed of crustaceans popularly known as swimming crab, is characterized by the presence of morphological adaptations that allow them to explore the water column. One of these adaptations, perhaps the most obvious one, is the modification of the last pair of pereiopods, in the shape of oars for swimming function. Callinectes ornatus is a species of swimming crab distributed from North Carolina, USA, to Rio Grande do Sul, Brazil (Williams & Williams 1984, Branco et al 2002) It is a species of great abundance in the coastal region of several Brazilian states, where its biology and distribution have been much studied (Mantelatto & Christofoletti 2001, Baptista et al 2003, Watanabe et al 2014, Tudesco et al 2012). Crabs of this species are often caught as bycatch in shrimp fishing, and individuals caught are often killed and discarded in the environment

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