Estudos dos aspectos alimentares e reprodutivos do ariacó Lutjanus synagris (Linnaeus, 1758) (Perciformes: Lutjanidae) capturado na costa amazônica do Maranhão, Brasil

Abstract

The feeding habit and aspects of the reproductive cycle of Lutjanus synagris were analyzed for one year (June 2018 to May 2019) based on 359 organisms acquired monthly through artisanal fishing, in a fishing area on the Amazon coast of Maranhenses, Brazil. The specimens were captured with a standard set of longline and gillnet type of sawmill type, stored in isothermal boxes and transported to the Laboratory of Fishery Biology - Biopesq, of the State University of Maranhão. Biometric data such as total length (LT), furcal length (FL) and standard length (SL), total weight (WT), gutted weight (GW), gonad mass (MG) were obtained. For the study of biological aspects, processing of the gonads was carried out and for the study of dietary aspects, an assessment and identification of stomach contents was made, classifying them at the lowest possible taxonomic level. Numerical and gravimetric methods were used to obtain the feed data. For the processing of the gonads, the samples went through specific protocols. The sexual proportion, the weight-length ratio, gonadosomatic index and condition factor, length of first maturation and temporal variations in the gonadal development of females and males were evaluated monthly and established. The environmental data - temperature and precipitation, were obtained through INMET - National Institute of Meteorology and NUGEO - Geoenvironmental Nucleus of the State University of Maranhão and related to feeding and reproduction regarding seasonality in the sample period. Throughout the sample period, fully filled stomachs were the least representative compared to the other replenishment classifications. In the quantification of stomachs 54 were empty due to regurgitation. The values of the degree of repletion were influenced by the sampled months (ANOVA, p<0.05). The diet presented a cumulative curve of 272 items, classified in 9 categories: crustaceans, mollusks, porifers, vegetables, vertebrates, annelids, fragments of fish and shrimp, unidentified organic matter (OMNI) and polymers. The identification of the items showed that decapod crustaceans were the most significant prey observed in the stomachs of L. synagris. The main food items were Brachyura and Carídeos. Reproductive results revealed a sex ratio of 1.40F:1M, with a favorable proportion for females in June and December. Females were predominant in the length class of 36.0 to 40.0 cm of LT and males of 32.0 to 36.0 cm of LT. The LWR presented an allometry coefficient less than three (b <3). The maturational aspects indicated five reproductive stages for males and females: immature, in development, capable of spawning, regression and regeneration. The species showed reproductive activity throughout the year and two reproductive peaks, one during the dry season, the other during the rainy season. The estimate of the average length of the first sexual maturity (L50) for grouped sexes was 26.16 cm 11 LT and can be considered a good indicator of a stock not yet explored, however, the knowledge of the reproductive characteristics of the species L. synagris can be used to define appropriate management and management policies for the species.