Crescimento relativo e maturidade sexual de Callinectes ornatus Ordway, 1863 (Brachyura, Portunidae) coletados em São Francisco do Paraguaçu, Município de Cachoeira, Estado da Bahia

Abstract

Callinectes ornatus Ordway, 1863 is a swimming crab that occurs from North Carolina (USA) to Rio Grande do Sul (Brazil), in estuarine regions, being regularly extracted for food purposes. The size at the onset of maturity (L50) has biological and economic importance, serving to draft laws to regulate the capture and sustainable use of population stocks. Callinectes ornatus is economically important for the riverside population that lives at Todos os Santos Bay. Therefore, the present study aimed to study the relative growth and size at the onset of maturity of this species, integrating morphometric, morphological and physiological criteria. The specimens were sampled monthly, from August 2013 to July 2014, with the aid of traps, at São Francisco do Paraguaçu fishing community, state of Bahia. All captured individuals were sexed and had their largest carapace width (LC; excluding the lateral spine) measured. In addition, the length and height of the larger (AQM, CQM) and smaller (AQm, CQm) chelipeds were measured, as well as the width of the fifth abdominal segment (LA). For the analysis of relative growth, the entire data set from the measurements mentioned above was used; LC was considered independent variable, while the measurements of the chelipeds and abdomen were considered dependent variables. Morphometric maturity was estimated based on linear regressions for each of the studied morphometric relationships, inwhich the juvenile and adult phases were clearly determined. Morphological maturity was estimated based on the adherence (young) or non-adherence (adults) of abdominal somites to thoracic sternites. Physiological maturity was based on the maturation stage of the gonads, determined macroscopically. In total, 1,471 specimens of C. ornatus (943 males and 528 females) were analyzed. Comparisons between juvenile and adult linear regression equations showed significant value, except for the LCxLA relationship that was not significant in both life stages of males. Young males and females showed allometric similarity only for the LCxCQM relationship. In the case of adult males, positive allometry occurred for all relationships, while females showed positive allometry in the LCxLA, LCxCQM and LCxCQm relationships and isometry in the others. Mean sizes of morphometric maturity were 50.58 mm (males) and 44.48 mm (females). Morphological maturity was estimated at 42.42 mm for males and 42.14 mm for females. Finally, the physiological maturity of males was 55.15 mm and 40.43 mm in females. Therefore, females reached maturity earlier than males. The difference in size found between males and females, especially in the adult phase could be explained by differential growth after the puberty moult, since males direct energy for growth and females for reproductive aspects. Morphological and morphometric maturity of females were very close, indicating synchrony, whereas the physiological maturity occurred earlier. Males showed later morphometric maturity and there was a synchrony between the morphological and physiological maturities. There was a tendency of C. ornatus to reach sexual maturity with a smaller size in regions of lower latitude. It is necessary to create regulation law for the capture of C. ornatus, because this species is not covered by theexisting regulation.