A atividade pesqueira na represa do Lobo-Broa (Itirapina, Brotas-SP): caracterização e composição da captura
Data
2017-11-15
Autores
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
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Descrição
Em 2002 a produção total de pescado no mundo foi de 133,0 milhões de toneladas. No Brasil, o volume total desembarcado foi de 822,2 mil toneladas, sendo cerca de 26,5% provenientes da pesca em água doce. A represa do Lobo-Broa (Itirapina, Brotas, SP; 22°15 S, 47°49 W) pode ter a sustentabilidade de seus recursos pesqueiros comprometida devido à proximidade de cidades como São Carlos e Itirapina. O objetivo geral deste trabalho foi estudar as pescarias esportivas e suas artes, realizar pescarias experimentais e estudar as composições das capturas de ambas pescarias. O trabalho foi apresentado em oito capítulos: (1) apresentação, (2) caracterização sócio-econômica dos pescadores esportivos, (3) descrição das capturas das pescarias esportivas, (4) descrição das capturas das pescarias experimentais, (5) análises estatísticas sobre as ambas, (6) estudo preliminar da seletividade das redes de emalhar utilizadas nas pescarias experimentais, (7) manejo de recursos pesqueiros em reservatórios e (8) considerações finais e recomendações. Entre setembro e novembro de 2004 foram aplicados 38 questionários para avaliação sócio-econômica dos pescadores esportivos e estes indicaram que as pescarias são praticadas principalmente por homens cujo padrão de vida se assemelha à média populacional do país. Entre setembro de 2002 a setembro de 2004 foram realizadas 1027 entrevistas sobre as capturas nos três principais locais de pescarias esportivas (praia, píer e horto florestal). As pescarias esportivas são praticadas com vara de pescar simples e com molinete, principalmente no horto florestal, local que apresentou maiores as cpues e onde foi registrado o maior esforço pesqueiro. A captura foi composta de Ciclídeos (cará, Geophagus brasiliensis, tilápia do Nilo, Oreochromis niloticus, tilápia do Congo, Tilapia rendalli e tucunaré Cichla monoculus), principalmente, embora a represa não tenha elevada produtividade pesqueira. A sazonalidade e o uso de isca/ceva não se mostraram estatisticamente significativos. Para avaliação da composição da ictiofauna da represa, foram realizadas sete pescarias experimentais entre novembro de 2002 e setembro de 2004 em três locais (horto/Itaqueri, meio e barragem), utilizando redes de emalhar. As espécies que tiveram maiores capturas relativas foram o cará e o lambari rabo amarelo (Astyanax altiparanae) e a região com maiores capturas relativas foi o horto/Itaqueri. A sazonalidade e a variação diuturna não foram significativas estatisticamente. Buscou-se detectar os fatores e a covariável estatisticamente significativos (P<0,05) sobre as capturas dos estudos acima, testando-se dois modelos de análise de covariância com três fatores (3 way ANCOVA). O estudo da seletividade das redes de emalhar para cada espécie por abertura de malha mostrou que as redes foram seletivas para os lambaris rabo amarelo e rabo vermelho (Astyanax scabripinnis paranae), sagüiru (Cyphocharax modesta) e cará. Para tuvira (Gymnotus carapo), cascudo (Hypostomus sp) e mandi (Pimelodella cf gracilis) esta arte não foi seletiva. Com base nos estudos acima, concluiu-se que as pescarias esportivas deveriam ser incentivadas visando o aumento do turismo na região e da produtividade pesqueira da represa. Porém, faz-se urgente a conscientização para que a ceva para os peixes deixe de ser utilizada, pois esta prática não aumenta as capturas e contribui para o processo de eutrofização represa
In 2002 the total production of fish in the world was 133,0 million tons. In Brazil, the total volume of fish was of 822,2 thousand tons, with 26,5% coming from freshwater fisheries. The Lobo-Broa reservoir (Itirapina, Brotas, SP; 22°15'S, 47°49'W), can have the sustainability of their fishing resources changed due to the proximity of cities as São Carlos and Itirapina. The general objective of this work was to study the sporting fisheries and their fishing gears, to do experimental fisheries and to study the compositions of the captures of both studies. The work was presented in eight chapters: (1) presentation, (2) socioeconomic characterization of the sporting fishermen, (3) description of the captures of the sporting fisheries, (4) description of the captures of the experimental fisheries, (5) statistical analyses on the both fisheries, (6) preliminary survey of the selectivity of the gillnets used in the experimental fisheries, (7) handling of fishing resources in reservoirs and (8) final considerations and recommendations. Among September and November of 2004 it was applied 38 questionnaires for socioeconomic evaluation of the sporting fishermen and these indicated that the fisheries are practiced mainly by men whose standard of living resembles each other to the population average of the country. Among September of 2002 to September of 2004, 1027 interviews were did on the captures in the three main places of sporting fisheries (praia, píer and horto florestal). The sporting fisheries are practiced with simple fishing rod and with reel, mainly in horto florestal, place that presented larger captures and where was concentrated the largest fishing effort. The capture is composed of Ciclídeos (cará, Geophagus brasiliensis, tilápia do Nilo, Oreochromis niloticus, tilápia do Congo, Tilapia rendalli and tucunaré Cichla monoculus), mainly, although the reservoir has not elevated fishing productivity. The seasonal variation and the bait use were not shown statistically significant. For fish fauna composition evaluation of the reservoir, seven experimental fisheries were accomplished between November of 2002 and September of 2004 in three places (horto/Itaqueri, meio and barragem), using gillnets. The species that had larger relative captures were the cará and the lambari rabo amarelo (Astyanax altiparanae) and the area with larger relative captures was the horto/Itaqueri. The seasonal variation and the daytime-nighttime variation were not statistically significant. It was detected the factors and the covariates statistically significant (P<0,05) on the captures of the studies above, being tested two models of analysis of covariance with three factors (3 way ANCOVA). The selectivity of the gillnets study for each species, for mesh size showed that the nets were selective for the lambari rabo amarelo, lambari rabo vermelho (Astyanax scabripinnis paranae), sagüiru (Cyphocharax modesta) and cará. For species as tuvira (Gymnotus carapo), cascudo (Hypostomus sp) and mandi (Pimelodella cf gracilis) this fishing gear was not selective. It was believed that the sporting fisheries should be motivated aiming the increment of the tourism in the area and increase of the fishing productivity of the reservoir. A larger understanding of the fishermen is urgent so that the bait stop being used, once this practice doesn't increase the captures and contributed to the eutrofication process in the reservoir
In 2002 the total production of fish in the world was 133,0 million tons. In Brazil, the total volume of fish was of 822,2 thousand tons, with 26,5% coming from freshwater fisheries. The Lobo-Broa reservoir (Itirapina, Brotas, SP; 22°15'S, 47°49'W), can have the sustainability of their fishing resources changed due to the proximity of cities as São Carlos and Itirapina. The general objective of this work was to study the sporting fisheries and their fishing gears, to do experimental fisheries and to study the compositions of the captures of both studies. The work was presented in eight chapters: (1) presentation, (2) socioeconomic characterization of the sporting fishermen, (3) description of the captures of the sporting fisheries, (4) description of the captures of the experimental fisheries, (5) statistical analyses on the both fisheries, (6) preliminary survey of the selectivity of the gillnets used in the experimental fisheries, (7) handling of fishing resources in reservoirs and (8) final considerations and recommendations. Among September and November of 2004 it was applied 38 questionnaires for socioeconomic evaluation of the sporting fishermen and these indicated that the fisheries are practiced mainly by men whose standard of living resembles each other to the population average of the country. Among September of 2002 to September of 2004, 1027 interviews were did on the captures in the three main places of sporting fisheries (praia, píer and horto florestal). The sporting fisheries are practiced with simple fishing rod and with reel, mainly in horto florestal, place that presented larger captures and where was concentrated the largest fishing effort. The capture is composed of Ciclídeos (cará, Geophagus brasiliensis, tilápia do Nilo, Oreochromis niloticus, tilápia do Congo, Tilapia rendalli and tucunaré Cichla monoculus), mainly, although the reservoir has not elevated fishing productivity. The seasonal variation and the bait use were not shown statistically significant. For fish fauna composition evaluation of the reservoir, seven experimental fisheries were accomplished between November of 2002 and September of 2004 in three places (horto/Itaqueri, meio and barragem), using gillnets. The species that had larger relative captures were the cará and the lambari rabo amarelo (Astyanax altiparanae) and the area with larger relative captures was the horto/Itaqueri. The seasonal variation and the daytime-nighttime variation were not statistically significant. It was detected the factors and the covariates statistically significant (P<0,05) on the captures of the studies above, being tested two models of analysis of covariance with three factors (3 way ANCOVA). The selectivity of the gillnets study for each species, for mesh size showed that the nets were selective for the lambari rabo amarelo, lambari rabo vermelho (Astyanax scabripinnis paranae), sagüiru (Cyphocharax modesta) and cará. For species as tuvira (Gymnotus carapo), cascudo (Hypostomus sp) and mandi (Pimelodella cf gracilis) this fishing gear was not selective. It was believed that the sporting fisheries should be motivated aiming the increment of the tourism in the area and increase of the fishing productivity of the reservoir. A larger understanding of the fishermen is urgent so that the bait stop being used, once this practice doesn't increase the captures and contributed to the eutrofication process in the reservoir
Palavras-chave
ANCOVA, pescarias experimentais, cpue, pescarias esportivas, manejo de recursos pesqueiros, ANCOVA, fisheries handling, experimental fisheries, cpue, sporting fisheries