Estimativa do comprimento de primeira maturação em espécies de peixes de dois reservatórios da bacia hidrográfica do rio Apodi/Mossoró, Semiárido brasileiro

Abstract

In between the species that may be hydrographed in the Eastern Northeast Atlantic of Brazil, is the Apodi / Mossoró River, covering a total area of 14,271 km². It is calculated by 618 reservoirs and 51 reservoirs. Among the reservoirs that make up the Apodi /Mossoró basin, two were used for the development of the present study, being they the Pau dos Ferros reservoir and the Santa Cruz reservoir. The objective of this study was to estimate the length of first maturation of the abundant species that make up the fish assembly of the reservoirs of the Apodi /Mossoró river basin and compare the results obtained in the study with the literature data in unmodified environments. The collections were performed quarterly between February 2010 and November 2016, at eight distinct points in the Santa Cruz reservoir and between February 2011 and November 2012 at the Pau dos Ferros reservoir. The fish were caught with mesh waiting nets ranging from 12 to 70 mm. In order to estimate the value of L50 the fish were separated in males and females and according to their stage of maturation, in juveniles (immature stage) and adults (other stages). Logistic regression was used to estimate the possibility of mature males and females. For species common to both reservoirs, ANCOVA was applied to verify if there was difference in maturation length. The data obtained in the analyzes were compared with results described in the literature, by searching the Scielo, Scopus, ISI web ofSciences platforms, using the words fish (fishes), first maturity, lenght at first maturity) and the name of the species studied. A total of 8,023 individuals were captured in the two reservoirs under study. The results of the estimation of first maturation length (L50) of male individuals of the species captured in the Santa Cruz reservoir ranged from 8,29 cm (C. lepidura) to 16,99 cm (H. malabaricus), for females ranged from 8,64 cm (C. lepidura) and 19,4 cm (H. malabaricus). The first maturation length (L50) estimate of the male individuals of the species captured in the Pau dos Ferros reservoir ranged from 8,58 cm (C. lepidura) to 16,95 cm (H. malabaricus), for females ranged from 7,33 cm (C. lepidura) and 16,96 cm (H. malabaricus). The ANCOVA result was significant only for males of the species C. lepidura (p <0.001) and P. brevis (p <0.009). Through the results it is possible to affirm that unfavorable conditions and the limitation of the resources of the environment to which they are submitted to the species for an indeterminate time are the primordial factors to delimit the length of first maturation of some species.