Abstract
Abstract The purpose of this study is to determine the parameters of the reproductive biology of seven commercial species at the Ramsar Site of the Baixada Maranhense to support fisheries management measures. The collections were carried out between 2012 and 2016. The reproductive period, sex ratio, weight-length relationship and first sexual maturity were evaluated for seven species of commercial importance. The sex ratio showed that females are predominant for all species, except for Plagioscion squamossissimus. The weight-length relationship indicated a greater investment in weight for Cichla monoculus and Hassar affinis, and a greater investment in length for Hoplias malabaricus, Plagioscion squamosissimus, Prochilodus lacustris, Pygocentrus nattereri, and Schizodon dissimilis. The reproductive activity of the species was predominant in the rainy season, but C. monoculus, H. malabaricus and P. lacustris showed the ability to reproduce in both seasons. As management measures for the region, it is suggested a change in the closed fishing season established by IBAMA, from December 1 to April 30, to ensure the protection of all commercial species in this study.
Highlights
The growing number of studies on the reproductive biology of fish is the result of efforts to understand biological processes and the preservation of aquatic ecosystems to contribute to the productivity of fishing systems (Lowerre-Barbieri, 2009; Jakobsen et al, 2016)
The goal of this study was to determine the main parameters of reproductive biology in seven species with commercial importance that inhabit the Ramsar site in Brazil, by examining sex ratio, weight-length relationship, reproductive periodicity and spawning season, to verify: whether the closed fishing season established by IBAMA (Ordinance No 85/2003), which runs from December to March, covers all of the species in this study in relation to spawning seasons
According to the last fishing bulletin issued by the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio, 2011), these species are caught in large volumes by continental fisheries throughout Brazil: Cichla monoculus Spix & Agassiz, 1831 (Tucunaré – 9,304.4 t); Hassar affinis (Mandi – 6,479.9 t); Hoplias malabaricus (Bloch, 1794) (Traíra – 9,894.0 t); Plagioscion squamosissimus (Pescada – 13,150.3 t); Prochilodus lacustris Steindachner, 1907 (Curimatá – 28,643.0 t); Pygocentrus nattereri Kner, 1858 (Piranha – 3,672.8 t); Schizodon dissimilis (Garman, 1890) (Aracu – 5,211.3 t)
Summary
The growing number of studies on the reproductive biology of fish is the result of efforts to understand biological processes and the preservation of aquatic ecosystems to contribute to the productivity of fishing systems (Lowerre-Barbieri, 2009; Jakobsen et al, 2016). Fishing systems where artisanal fishing is the main activity and that might become environments with low fish stocks require more and deeper studies (LowerreBarbieri et al, 2011), especially in places where little is known about the fishery resources. This is the case of Brazil and its large number of rivers and artisanal fishing communities, as well as its large environmental Conservation Districts and protected areas used for fishing, mainly for subsistence purposes. In Maranhão State, there are large protected areas of ecological and economic importance, three of which can be mentioned here for their relevance in fishing: the Baixada Maranhense, the Reentrancias Maranhenses, and a portion of the Manoel Luís Marine State Park. Artisanal fishing is the main source of income and subsistence, and it occurs on a small scale, it has negative impacts on local fish fauna
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