Induced reproduction in a migratory teleost species by water level drawdown

Abstract

Captive reproduction is one of the problems faced in aquaculture requiring the manipulation of environmental factors and/ or hormonal treatment. Thus, we seek to verify experimentally which gonadal changes were present in mature individuals of Astyanax altiparanae arising from decreased water level. Collections were made every four hours, initiated four hours before and finished 28 hours after stimulation, at the Fish Farming Station of Companhia Energética de São Paulo, São Paulo, Brazil. The gonads were analyzed by light microscopy. The females had ovaries in the spawning capable phase until 12h; in 16h, in a more advanced stage of spawning capable phase; and, from 20h, in the regressing phase. Males had testes in the spawning capable phase until 8h; in 12h, in a more advanced stage of spawning capable phase; and, from 16h, the return to the spawning capable phase. The morphological description was corroborated by the proportion of cell classes. Females presented variation on the gonadosomatic index, but it was not found an emptying of the gonad for neither sex. The process of inducing reproduction with water level drawdown was considered satisfactory, since both sexes presented a reduction in the number of mature gametes at the end of the sample period.Reprodução em cativeiro é um dos problemas enfrentados na aquicultura exigindo a manipulação de fatores ambientais e/ ou tratamento hormonal. Assim, verificou-se experimentalmente as alterações gonadais presentes em indivíduos adultos de Astyanax altiparanae decorrentes da diminuição do nível da água. As coletas foram realizadas a cada quatro horas, iniciadas quatro horas antes e encerradas 28 horas após a estimulação, na Estação de Piscicultura da Companhia Energética de São Paulo, São Paulo, Brasil. As gônadas foram analisadas por microscopia de luz. As fêmeas apresentaram ovários na fase de apto à reprodução até 12h; em 16h, um estágio mais avançado desta fase; e, a partir das 20h, na fase de regressão. Os machos tiveram os testículos em fase de apto à reprodução até 8h; em 12h, um estágio mais avançado desta fase; e, a partir das 16h, o retorno à fase de apto à reprodução. A descrição morfológica foi corroborada pela proporção das classes celulares. As fêmeas apresentaram variação no índice gonadossomático, mas não foi estabelecido o esvaziamento das gônadas para nenhum dos sexos. O processo utilizado para a indução à reprodução foi considerado satisfatório, uma vez que ambos os sexos apresentaram redução no número de gametas maduros no final do período de amostragem.

Environmental manipulation on Astyanax altiparanae out of season spawning

“…In this study, it was found that the percentage of spawned females, the number of eggs produced, and the absolute fecundity were higher in G2 group (81.25; 220,250; 8,471.14 ± 860.08%, respectively) than in G1 group (9.38; 8,930; 2,976.57 ± 1,085.71%, respectively). Although A. altiparanae only reproduce in captivity after reproductive management and many management techniques have already been used and standardized for this species (Felizardo et al, 2012;Chehade et al, 2015;Cassel et al, 2017), hypophysation has been widely used since it leads to greater egg production and allows controlling the breeders and the time of spawning (Felizardo et al, 2012). Also, hormonal induction with CCPE has shown great results in inducing reproduction of native fish (Arantes et al, 2011;Sanches et al, 2011;Freitas et al, 2013).…”

Ovarian development and the reproductive profile of Astyanax altiparanae (Teleostei, Characidae) over one year: Applications in fish farming

“…The other female tank served as a control group in which no reproductive management practices were performed at any time during the collection periods. The reproductive management practice used in this study has been briefly described by Chehade et al [20]; however, the exact method used herein was as follows:…”

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“…Astyanax altiparanae OVARIAN MATURATION… A. altiparanae attains full maturity relatively fast (only four months) and spawns easily with the slightest variation in water levels in captivity (CHEHADE et al, 2015), but in order to ensure the production of a sufficient number of fingerlings, hormonal induction protocols are applied for farming purposes (FELIZARDO et al, 2012). A. altiparanae is an egg laying without parental care (SUZUKI et al, 2005), multiple spawning fish (SATO et al, 2006;CHEHADE et al, 2015) which can spawn over the year; however, the peak of its spawning activity happens in the warmer months -spring and summer (PRADO et al, 2011;CASSEL et al, 2017;JESUS et al, 2017). Differently from most tropical egg layers (ZANIBONI-FILHO and WEINGARTNER, 2007;PORTO-FORESTI et al, 2010;SCHORER et al, 2016;PEREIRA et al, 2017), A. altiparanae's final maturation and ovulation are achieved through a single carp pituitary extract (CPE) dose (SATO et al, 2006).…”

“…Even with a significant increase in its annual production (6% between 2013 and 2014 (IBGE, 2014)), currently it does not meet the existing demand (ROSA and SIMÕES, 2016). This species is also important for fishing, as well as for restocking programs (HASHIMOTO et al, 2015), and has been widely used as a model in studies concerning fish reproduction (SILVA et al, 2011;WEBER et al, 2013;GOMES et al, 2013;ADOLFI et al, 2015;CHEHADE et al, 2015;YASUI et al, 2015;SANTANA et al, 2015;KIDA et al, 2016).…”