Aspectos reprodutivos e caracterização dos otólitos do agulhão Tylosurus acus acus (Lacepède, 1803) no Arquipélago de São Pedro e São Paulo, Brasil

Abstract

The sailfish Tylosurus acus acus is a subspecies of belonid resident and abundant in the São Pedro and São Paulo archipelagos, for which there are no documented data on its biology throughout the South Atlantic Ocean. Reproduction and characterization of otoliths are important aspects to be studied, and unknown for T. acus acus. This study will provide the first information on the biology and characterization of otoliths of this species. From March 2019 to March 2020, 120 gonads were collected, measured, weighed, and used for the reproductive study, while 101 pairs of otoliths were collected. Gonads were classified macroscopically according to the Brown-Peterson scale. The ratio of gonads to each other was proposed by Schaeffer (1956). Mean length at sexual maturity was calculated using the relative frequency of adults per length class. Morphological characters were rostrum, antirostrum, acoustic sulcus, ostium, tail, and margins. The measures used for the calculated heights were morphometric measurements, length, and weight of the otolith, which were correlated with each other and with length. The observed sex ratio was 3.4F:1M, which could be due to sex separation. The monthly distribution of the proportion of maturation periods indicates that the site is likely a breeding area for the species. Abiotic and biotic factors, especially temperature, are essential for biological changes in the species. Correlations between high individuals suggest that measures of growth together and how they grow, as well as otolith changes. The information obtained in this study may contribute to the conservation of the Atlantic Ocean.