Abstract
Lutjanid species exhibit multiple spawning behaviour during an extended spawning season in warm months, asynchronous oocyte development and indeterminate fecundity. Although early studies have contributed to knowledge of the reproductive cycle of many species within the group, they have not considered aspects about the number of cortical alveoli oocyte stage throughout maturity phases along spawning season. The latter aspect is also considered very important to confirm indeterminate fecundity hypothesis. In the present study, were analyzed 154 Brazilian snapper Lutjanus alexandrei female gonads obtained from artisanal fisheries in Pernambuco State (Brazil) between October 2010 and March 2011. Were measured oocyte size frequency distribution for maturity phases (developing, spawning capable and actively spawning), and oocyte development stage (unyolked oocytes, cortical alveoli, primary, secondary and tertiary vitellogenic oocytes and hydrated oocytes), and also the oocyte stage frequency during spawning season. The frequency of cortical alveoli oocyte stage was constantly found in the spawning period (>37%), showing slight variation throughout maturity phases. The absence of gap in the oocyte size frequency distribution between primary and secondary oocyte growth stages during spawning season is a strong indicator of continuous oocyte recruitment from reserve stocks. In addition, co-occurrence of tertiary vitellogenic oocytes, hydrated oocytes, post-ovulatory follicles and yellow-brown bodies in the histological sections of ovaries reinforce indeterminate fecundity hypothesis.
Highlights
The snappers, family Lutjanidae, are reef and mangrove fish species, commonly known as red fishes
During vitellogenesis the oocytes develop from primary growth stage to cortical alveolar (CA) which is the early stage of the secondary growth (Figure 2a-b), to progress throughout primary Vtg1 and secondary Vtg2 (Figure 2c), and tertiary vitellogenesis stages Vtg3 (Figure 2d)
The oocyte maturation begins with germinal vesicle migration (GVM, early hydration), going to germinal vesicle breakdown (GVBD, middle hydration) and hydrated oocyte stage (HO, final hydration) when it is previous to spawning (Figure 2e-f)
Summary
The snappers, family Lutjanidae, are reef and mangrove fish species, commonly known as red fishes. The Brazilian snapper Lujanus alexandrei (Moura and Lindeman, 2007) is a recently described species of Lutjanidae, a family which includes thirteen species with confirmed occurrence in Brazil (Floeter et al, 2003; Freire and Carvalho-Filho, 2009). Some interesting features of this particular species are its endemic nature, a trait that had never been reported before for any other snapper in Brazil, and its limited area of occurrence along the coastline between the state of Maranhão and Bahia (Moura and Lindeman, 2007). Because of the recent description, very little information is available on the Brazilian snapper on its reproductive biology
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