Reproductive strategy and fecundity of the keystone species Paralonchurus brasiliensis (Teleostei, Sciaenidae): an image processing techniques application

Knowledge of oocyte development and fecundity type (or oocyte recruitment process) is essential to understand the reproductive strategy of any fish species (Hunter et al. 1992; Murua and Saborido-Rey 2003; Richard and Kestenmont 2003; Murua and Motos 2006). This strategy has been assessed based mainly on the knowledge of the stage-specific oocyte size-frequency distribution during the reproductive cycle, evolution of the number of advanced yolked oocytes in the ovary, seasonal variation in the mean diameter of the advanced vitellogenic oocytes and incidence of atretic oocytes through the spawning season (Walker et al. 1994; Murua and Saborido-Rey 2003). Reproductive strategy among fish species can acclimate to climate and/or anthropogenic changes (Stearns 1992). Thus, the results of these studies are of great importance and widely applied in fisheries science because, to some extent, the fecundity studies, including the description of the reproductive strategy, determine the resilience of fish populations to fishing (Morgan 2008). Moreover, the studies on reproductive strategies of fishes determine the type of method chosen for estimating the individual fecundity and egg production method for the assessment of the spawning stock biomass (Armstrong andWitthames 2012; Ganias 2013), as well as for understanding fish phenology in a world of changing climate (Soria et al. 2008; Miranda et al. 2009; Pankhurst and King 2010; Strussmann et al. 2010). Fecundity can also be used as an indicator of population’s reproductive potential, being a reference point for the management and sustainable fisheries (Hunter et al. 1992). Nevertheless, there are many more data available on other life history parameters of fish than on the fecundity (Tomkiewicz et al. 2003). Fecundity comes from a relatively small number of species, the majority of which are of commercial importance (Tyler and Sumpter 1996). Paralonchurus brasiliensis (Steindachner, 1875), commonly known as the Banded Croaker, is widely distributed along the Atlantic Coast from Central to South America (Menezes and Figueiredo 1980). This species is the most frequently and abundant sciaenid captured as by-catch by shrimp fishery trawls in southeastern Brazil (Nonato et al. 1983; Braga et al. 1985; Braga 1990; Haimovici et al. 1996; Souza et al. 2008). It can reach 300 mm in total length (common to 250 mm), feeding mainly on crustaceans and polychaetes (Menezes and Figueiredo 1980; Branco et al. 2005). Environ Biol Fish (2015) 98:2093–2108 DOI 10.1007/s10641-015-0432-2