Artisanal fisheries in a Brazilian hypereutrophic reservoir: Barra Bonita reservoir, middle Tietê river
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Data
2011-11-01
Autores
Novaes, J. L. C.
Carvalho, Edmir Daniel [UNESP]
Título da Revista
ISSN da Revista
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Editor
Instituto Internacional de Ecologia
Resumo
Esse estudo avaliou aspectos quantitativos qualitativos do desembarque pesqueiro no reservatório hipertrófico de Barra Bonita. Os dados foram coletados mensalmente (julho/2004-junho/2006) em três localidades e informações sobre captura, esforço de pesca e técnicas de pesca foram registrados de 745 desembarques, totalizando 86.691,9 kg de pescado capturados. As espécies mais capturadas foram as exóticas tilápias, especialmente a tilápia-do-nilo (Oreochromis niloticus L.), que representaram 82,5% da biomassa total. A produtividade pesqueira do reservatório foi de 11,1 kg/ha-1/dia-1 com uma Captura Por Unidade de Esforço de 62,4 kg/pescador-1/dia-1 . Cinco técnicas de pesca foram identificadas: tarrafas, rede de espera, rede de arrasto, pesca da batida e pesca da batida + rede de espera. Análise de DCA relacionou as estratégias ativas com a captura de tilápia, as estratégias passivas com a captura de Pimelodus maculatus (Lacepède) e Triporthues angulatus (Spix & Agassiz) e a estratégia mista com a captura de tilápia, cascudos e Prochilodus lineatus (Valenciennes). Os resultados da ANCOVA foram significativos para todas as variáveis analisadas (época, local de pesca e técnicas de pesca). Os resultados mostram uma substituição da pesca da corvina, Plagioscion squamossisimus (Heckel) na década de 1990, pela tilápia-do-nilo. A substituição pode ter sido provocada pelo aumento da eutrofização do reservatório, aliado à mudança das estratégias de pesca. A pesca no reservatório de Barra Bonita seguiu padrões de outros reservatórios eutrofizados brasileiros, com a pesca sustentada pela exótica tilápia-do-nilo.
This study examines the qualitative and quantitative aspects of fishery landings at the hypereutrophic Barra Bonita reservoir, Brazil. Data were collected each month (July/2004-June/2006) at three localities and the reported catch, fishing effort and fishing techniques were recorded from 745 landings, comprising a total fish catch of 86,691.9 kg. The most caught species were exotic tilapias, especially the Nile tilapia (Oreochromis niloticus L.), which represented 82.5% of the total biomass. The reservoir's fishery productivity was 11.1 kg/ha-1/day-1 with a Catch Per Unit Effort of 62.4 kg/fisher-1/day-1. Five fishing techniques were identified: cast net, gill net, trawl net, beating gill net, and beating gill net + gill net. The analysis of DCA related the active strategies for the tilapia catch, to the passive strategies for the Pimelodus maculatus (Lacepède) and Triportheus angulatus catches (Spix & Agassiz), and the mixed strategies for the tilapia, catfish and Prochilodus lineatus (Valenciennes) catches. ANCOVA results were significant for all the variables analysed (season, fishing location and fishing technique). The results showed that fishing for corvina Plagioscion squamosissimus (Heckel), predominant in the 1990s, had been replaced by fishing focused on the Nile tilapia. This substitution appears to be due to the increasing levels of eutrophication in the reservoir, combined with changes in fishing techniques. The pattern of the fisheries in Barra Bonita Reservoir follow those in other eutrophic Brazilian reservoirs, with catches of the exotic Nile tilapia predominating.
This study examines the qualitative and quantitative aspects of fishery landings at the hypereutrophic Barra Bonita reservoir, Brazil. Data were collected each month (July/2004-June/2006) at three localities and the reported catch, fishing effort and fishing techniques were recorded from 745 landings, comprising a total fish catch of 86,691.9 kg. The most caught species were exotic tilapias, especially the Nile tilapia (Oreochromis niloticus L.), which represented 82.5% of the total biomass. The reservoir's fishery productivity was 11.1 kg/ha-1/day-1 with a Catch Per Unit Effort of 62.4 kg/fisher-1/day-1. Five fishing techniques were identified: cast net, gill net, trawl net, beating gill net, and beating gill net + gill net. The analysis of DCA related the active strategies for the tilapia catch, to the passive strategies for the Pimelodus maculatus (Lacepède) and Triportheus angulatus catches (Spix & Agassiz), and the mixed strategies for the tilapia, catfish and Prochilodus lineatus (Valenciennes) catches. ANCOVA results were significant for all the variables analysed (season, fishing location and fishing technique). The results showed that fishing for corvina Plagioscion squamosissimus (Heckel), predominant in the 1990s, had been replaced by fishing focused on the Nile tilapia. This substitution appears to be due to the increasing levels of eutrophication in the reservoir, combined with changes in fishing techniques. The pattern of the fisheries in Barra Bonita Reservoir follow those in other eutrophic Brazilian reservoirs, with catches of the exotic Nile tilapia predominating.
Descrição
Palavras-chave
eutrofização, Oreochromis niloticus, pesca de pequena escala, espécie exótica, estratégias de pesca, eutrophic, Oreochromis niloticus, small-scale fisheries, exotic species, fishing strategies
Como citar
Brazilian Journal of Biology. Instituto Internacional de Ecologia, v. 71, n. 4, p. 821-832, 2011.