Dinâmica reprodutiva da sardinha-laje Opisthonema oglinum, Lesueur, 1818 capturada no litoral norte de Pernambuco, Brasil

Abstract

This work deals with the reproductive strategies of Thread herring, Opisthonema oglinum, a teleost fish belonging to the Clupeidae family, abundant in the Brazilian Northeast coast. Sampling was carried out in the northern coast of the state of Pernambuco between May 2016 and April 2018. A total of 497 specimens were collected and sexed, 304 gonads sectioned for maturational evaluation. Females were more frequent than males, with a sex ratio of 1.5 females: 1 male. The total length of the females ranged from 8.0 to 28.3 cm and that of males from 8.1 to 28.0 cm. The first maturation size was estimated at 11.43 cm of total length for females and 12.5 of total length for males. The Gonadosomatic Index (GSI) in conjunction with the monthly frequency distribution of the gonad maturation stages, indicated a seasonal reproductive cycle with spawning occurring from August to February, with a peak for females November and February and for males in September and February. The values indicate a potential number of 19 spawns during the year using the OH method and 25 using the POF method. The absolute fecundity of 15 mature females ranged from 44,100 to 86,513 oocytes. Histological analyzes of 70 gonads allowed to describe the characteristics of oocyte growth for the species. The diameters of oocytes phases of sexual maturity, "developing", "able to spawn" and "active spawning" were measured and all ovocitários stages (alveolar cortical primary vitelogenesis, secondary, tertiary, hydrated oocytes and migration and vesicle breaks germinal) were measured and the frequency of occurrence during the spawning period evaluated. The absence of a range in oocyte diameter frequency across all phases of gonadal maturity is a strong indicator of continuous recruitment of oocytes from the stock stock. The presence of oocytes at various stages of development and distinct diameters in the same ovary confirms spawning type spawning with asynchronous oocyte development. Knowledge of the reproductive biology of Opisthonema oglinum in Pernambuco coast are fundamental to guide management measures and preservation of the species, thus contributing to a better understanding of their population dynamics in the region, generating information that is capable of ensuring the conservation of the species and sustainability of fishing activity.