Population structure and reproductive biology of Astyanax gymnodontus (Characiformes: Characidae), a poorly known endemic fish of the Iguaçu River basin, Brazil
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| Format: | Artículo científico |
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Universidad de Costa Rica
2016
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| author | Matheus Tenório Baumgartner |
| author_facet | Matheus Tenório Baumgartner |
| contents | Population structure and reproductive biology of Astyanax gymnodontus (Characiformes: Characidae), a poorly known endemic fish of the Iguaçu River basin, Brazil Matheus Tenório Baumgartner Pedro Rogério Leandro da Silva Gilmar Baumgartner Biología RAI fish ecology gonadosomatic index Reproductive biology Success in fish breeding depends on reproduction intensity, periodicity and the place where it occurs.Information about fish species reproduction is important to assist managers, and to determine conservation andmanagement strategies. The fish assemblage of the Iguaçu River basin is already known for its high endemism,and despite this privilege, the large number of dams built along it, threat this particular biodiversity. Astyanaxgymnodontus is an endemic fish species and studies on its population structure and reproductive biology areimportant, since they represent the first step for further community studies. Our objective was to evaluate someaspects of the population structure and reproductive biology of A. gymnodontus in the influence area of SaltoSantiago dam, Iguaçu River, Paraná State, Brazil. Sampling was made monthly from July 2003 to June 2005, andbimonthly from July 2005 to March 2013, at five sites in the influence area of Salto Santiago dam. Fishes werecollected using 10 m length gillnets with meshes ranging from 2.5 to 6.0 cm between non-adjacent knots andtrammel nets with inner meshes of 6.0 cm between non-adjacent knots. Nets were arranged on surface, bottomand margins of each site, exposed for 24 h. Additional drags on littoral areas were performed from January toMarch and October to December from 2009 to 2011, with 50.0 m nets, 0.5 cm mesh size, for juveniles capture.We captured and analyzed 21 932 individuals, being 9 249 females and 12 683 males, representing 42.2 % and57.8 %, respectively. The average body length was 8.8 cm for females and 8.3 cm for males. The average weightwas 18.8 g for females and 16.0 g for males. Sex ratio calculated for the entire period was 1.8 males/female.Males were more abundant than females in 73.2 % of samples and significant differences were observed in 35.3% of samples. The estimated length at first maturity (SL50) was 6.4 cm for females and 6.2 cm for males. We suggestthat sexual differences in body length and weight, and sex ratio occurred as a result of sexual differences inenergy allocation. Females spend more energy on body growth, which means more eggs production and higherfecundity. As an integrated response, males spend more energy on sperm production, in competition with othermales, leading to a smaller body size. Differences in estimated SL50 might be an indicator of this sexual differencein energy allocation. The reproduction period was from September to February, with greater intensity at thebeginning of this period, and the sites of highest reproductive intensity were those immediate downstream fromdams, and therefore with more riverine characteristics. 2016 artículo científico 0034-7744 https://www.redalyc.org/articulo.oa?id=44943437007 en http://www.redalyc.org/revista.oa?id=449 Revista de Biología Tropical application/pdf Universidad de Costa Rica Revista de Biología Tropical (Costa Rica) Num.1 Vol.64 |
| format | Artículo científico |
| id | redalyc_44943437007 |
| institution | Redalyc |
| language | en |
| publishDate | 2016 |
| publisher | Universidad de Costa Rica |
| spellingShingle | Population structure and reproductive biology of Astyanax gymnodontus (Characiformes: Characidae), a poorly known endemic fish of the Iguaçu River basin, Brazil Matheus Tenório Baumgartner Biología RAI fish ecology gonadosomatic index Reproductive biology Population structure and reproductive biology of Astyanax gymnodontus (Characiformes: Characidae), a poorly known endemic fish of the Iguaçu River basin, Brazil Matheus Tenório Baumgartner Pedro Rogério Leandro da Silva Gilmar Baumgartner Biología RAI fish ecology gonadosomatic index Reproductive biology Success in fish breeding depends on reproduction intensity, periodicity and the place where it occurs.Information about fish species reproduction is important to assist managers, and to determine conservation andmanagement strategies. The fish assemblage of the Iguaçu River basin is already known for its high endemism,and despite this privilege, the large number of dams built along it, threat this particular biodiversity. Astyanaxgymnodontus is an endemic fish species and studies on its population structure and reproductive biology areimportant, since they represent the first step for further community studies. Our objective was to evaluate someaspects of the population structure and reproductive biology of A. gymnodontus in the influence area of SaltoSantiago dam, Iguaçu River, Paraná State, Brazil. Sampling was made monthly from July 2003 to June 2005, andbimonthly from July 2005 to March 2013, at five sites in the influence area of Salto Santiago dam. Fishes werecollected using 10 m length gillnets with meshes ranging from 2.5 to 6.0 cm between non-adjacent knots andtrammel nets with inner meshes of 6.0 cm between non-adjacent knots. Nets were arranged on surface, bottomand margins of each site, exposed for 24 h. Additional drags on littoral areas were performed from January toMarch and October to December from 2009 to 2011, with 50.0 m nets, 0.5 cm mesh size, for juveniles capture.We captured and analyzed 21 932 individuals, being 9 249 females and 12 683 males, representing 42.2 % and57.8 %, respectively. The average body length was 8.8 cm for females and 8.3 cm for males. The average weightwas 18.8 g for females and 16.0 g for males. Sex ratio calculated for the entire period was 1.8 males/female.Males were more abundant than females in 73.2 % of samples and significant differences were observed in 35.3% of samples. The estimated length at first maturity (SL50) was 6.4 cm for females and 6.2 cm for males. We suggestthat sexual differences in body length and weight, and sex ratio occurred as a result of sexual differences inenergy allocation. Females spend more energy on body growth, which means more eggs production and higherfecundity. As an integrated response, males spend more energy on sperm production, in competition with othermales, leading to a smaller body size. Differences in estimated SL50 might be an indicator of this sexual differencein energy allocation. The reproduction period was from September to February, with greater intensity at thebeginning of this period, and the sites of highest reproductive intensity were those immediate downstream fromdams, and therefore with more riverine characteristics. 2016 artículo científico 0034-7744 https://www.redalyc.org/articulo.oa?id=44943437007 en http://www.redalyc.org/revista.oa?id=449 Revista de Biología Tropical application/pdf Universidad de Costa Rica Revista de Biología Tropical (Costa Rica) Num.1 Vol.64 |
| title | Population structure and reproductive biology of Astyanax gymnodontus (Characiformes: Characidae), a poorly known endemic fish of the Iguaçu River basin, Brazil |
| topic | Biología RAI fish ecology gonadosomatic index Reproductive biology |
| url | https://www.redalyc.org/articulo.oa?id=44943437007 |