Avaliação das relações morfométricas da Matuta lunaris Forsskal (1775) capturado como fauna acompanhante na pesca semi-industrial de arrasto de camarão na Baía de Maputo

Abstract

The present research had with the aim of evaluating the morphometric relationships of the crab Matuta lunaris Forsskal (1775) captured as by-catch in semi-industrial fisheries shrimp trawling in Maputo Bay. The study was carried out in trawling fishing activities of shrimp in the 2020 fishing season. In the trawls they were selected and separated from the others species the crabs targeted by the study and preserved in plastic bags later preserved in containers with ice, for later analysis in the laboratory of the History Museum Natural. The differentiation between male and female was through morphological characters with a focus to the abdomen as described in the literature. Carapace width (CL), carapace length (CL), same (CW) were determined using the standard steel caliper (0.01 mm). The weight total body weight (W) was determined using a standard electronic scale with a precision of 0.01g. The relationships morphometric data were determined using the formula W = a × CL b and the CPUE using the formula n CPUE = t . Results: Forty-one Matuta lunaris crabs (34 males and 7 females) females) with average body weights of 24.3 g (M) and 13.6 g (F), carapaces with lengths of 63.9mm (M) and 57.7mm (F) and widths of 38.5mm (M) and 37.9mm (F). Relationships analyzed morphometrically, females have an allometric coefficient ‘b’ greater than 3, meaning a positive allometric growth for both W/CL and W/CW meaning higher rate of growth in body weight than in length and width while males both relations (W/CL and W/CW) have coefficient ‘b’ less than 3, indicating a growth negative allometric with r 2 equal to 0.76 and 0.79 respectively meaning that there is a higher rate growth in carapace width and length than in weight. At the level of damage the most predominant were males with paws (18%) and chelae (12%) absent from the total number of individuals males collected and only 15% of females were missing only one or both chelae of the total number of females collected. Conclusions: males of the crab Matuta lunaris have a larger body size compared to females, demonstrating sexual dimorphism. The weight/width and weight/length ratio showed positive allometric growth in females and negative allometric growth in males of M. lunaris. The capture per unit of effort (CPUE) ranged from 0.009 to 0.05 (Kg*day -1 ) throughout the quarter (May to July 2020)(TRADUÇÃO NOSSA)