Gonadal steroids levels and vitellogenesis in the formation of oocytes in Prochilodus lineatus (Valenciennes) (Teleostei: Characiformes)

Abstract

The objective of this study was to obtain information about the possible mechanisms related to poor reproductive performance in tropical rheophilic fish. To that effect, cages (Cs) and earthen ponds (EPs) were used as experimental systems to provide unsuitable and suitable conditions, respectively, for curimbatá (Prochilodus lineatus) breeders. Fish were maintained under experimental conditions for 18 months, and during this period females were randomly sampled every two months for biometric analysis (n=30), blood (n=5/sampling) and ovary (n=5/sampling). After this period EPs females (EPFs) and Cs females (CFs) were submitted to the induced breeding experiments. The results showed that rearing curimbatá for such long time in a cage at this stocking density, reduces its growth, plasma E2 levels and vitellogenesis. During vitellogenesis, the mean plasma estradiol levels of CFs were three times lower than those of EPFs (P<0.01). CFs presented poorer results than EPFs for all the examined parameters of reproductive performance. Taken together these data showed that the reduced estradiol levels during vitellogenesis (and the consequently less intense transition from the previtellogenic to vitellogenic phase) and reduced amounts of yolk are mechanisms associated with the formation of low quality oocytes and shortened and delayed breeding season in this species. Moreover, our data showed that the onset of vitellogenesis (six months before the spawning season) must be considered as a key period related to the formation of oocytes of good quality, and adequate management should be provided throughout the year.Este estudo teve como objetivo gerar informações básicas sobre os possíveis mecanismos relacionados com os resultados desfavoráveis obtidos com o desempenho reprodutivo em peixes reofílicos tropicais. Para isso tanques-rede (Cs) e viveiros escavados (EPs) foram utilizados como sistemas experimentais para propociar respectivamente condições inadequadas e adequadas para reprodutores de Prochilodus lineatus. Os peixes foram mantidos por 18 meses em viveiros escavados (EPs) e tanques-rede (Cs), e durante este período, foram aleatoriamente coletados a cada dois meses para análise biométrica (n=30), coleta de sangue (n=5/tratamento) e amostragem do ovário (n=5/tratamento). Após este período as fêmeas mantidas em EPs (EPFs) e as fêmeas mantidas em Cs (CFs) foram submetidas aos experimentos de reprodução induzida. Os resultados mostraram que manter curimbatás por este período em Cs, na densidade de estocagem utilizada, reduz seu crescimento, níveis plasmáticos de E2 e vitelogênese. Durante a vitelogênese, os níveis plasmáticos de estradiol das CFs foram três vezes menores do que os das EPFs (P <0,01). As CFs apresentaram resultados inferiores aos das EPFs para todos os parâmetros analisados de desempenho reprodutivo. Em conjunto, estes dados mostram que os níveis reduzidos de estradiol durante a vitelogênese (bem como o consequente atraso na transição da fase previtelogênica para a vitelogênica) e as quantidades reduzidas d...

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“…In other studies, however, has been no such correlation (Linhares et al, 2014). In this population the size of the oocytes can also be affected adverse habitat (Hainfellner et al, 2012) and how many times they consisted of female eggs (in the first spawning are larger oocytes) (Kjesbu, 1989).…”

Reproductive cycle of the Amazonian planktivorous catfish Hypophthalmus marginatus (Siluriformes, Pimelodidae)

“…The vitellogenic process of H. marginatus was like that of other tropical Characiformes rheophilic species (Hainfellner, Souza, et al, ; Schorer et al, ), occurring in October or November, approximately 2 months before the spawning season (spring/summer). In the first reproductive cycle, an abrupt increase in E 2 levels between November and December was concomitant with a GSI elevation and with the occurrence of maturing and mature females.…”

“…Similar to that of its congener, Hypophthalmus edentatus (Carvalho, ), H. marginatus exhibited a very well‐defined spawning season from November to February that was more intense from November to December. We described a long resting period (approximately six months during the autumn and winter months) typical of migratory total spawners in natural (Alvarenga, Bazzoli, Santos, & Rizzo, ; Lima‐Junior & Goitein, ; Narahara, Basile‐Martins, Godinho, & Cipolli, ) or captive conditions (Ganeco, Nakaghi, Urbinati, Dumont‐Neto, & Vasques, ; Hainfellner, Souza, Moreira, Nakaghi, & Batlouni, ; Schorer, Moreira, & Batlouni, ). All these characteristics indicate that the species presents a reproductive cycle typical of tropical migratory total spawners (Borella et al, ; Rizzo & Bazolli, ; Vazzoler, ; Zaniboni‐Filho & Nuñer, ); however, the presence of three batches of oocytes in mature females indicated that the species may spawn more than once within the same breeding season.…”

“…For the congener species H. edentatus (Carvalho, ), GSI values reported for mature females were also relatively low (6.4%), indicating that the maparás may present small GSI values in comparison to other tropical migratory fish. The GSI values of mature females of Brycon orbignyanus (Ganeco et al, ), Piaractus mesopotamicus (Romagosa, Paiva, Godinho, & Storfer, ), Pseudoplatystoma fasciatum (Romagosa et al, ), Prochilodus lineatus (Hainfellner, Souza, et al, ), Leporinus piau (Araújo, Oliveira, Costa, & Novaes, ), Salminus hilarii (Honji et al, ; Moreira et al, ), Rhamdia quelen (Reidel et al, ), Brycon amazonicus (Hainfellner, de Souza, Munoz, & Batlouni, ) and Leporinus elongatus (Pereira, Boscolo, Moreira, & Batlouni, ) were 15%, 15%, 15%, 19%, 20%, 16%, 10%, 15% and 16% respectively. The relatively small GSI values of species belonging to the Hypophthalmus genus may be associated with the small celomic cavity and the displacement of the organs towards the ventral part of the animal, whereas the caudal portion of the animal is entirely occupied by muscles, which is associated with its high fillet yield (Souza & Inhamuns, ), and also attributable to the fact that these species do not form fat deposits; rather, the fat is diffused in muscle tissue, giving the fillet its high fat content (Carvalho, ).…”

Development of the Vertebral Column and Caudal Skeleton in Prochilodus lineatus Larvae under Laboratory Conditions

“…mance in culture, highlighting the fast growth and good use of low quality foods (Croux, 1992). Several studies were performed on the histology of the digestive tract (Domitrovic, 1983), reproduction (Croux;Hainfellner et al, 2012), embryonic development (Botta et al, 2010) and growth (Furuya et al, 1999). On the other hand, studies on abundance as part of ichthyoplankton were also carried out in relation to the growth chronology from yolk larvae stage to juvenile (Sverlij et al, 1993;Fuentes, 1998).…”