Ecologia de tres comunidades de pescadores do Rio Piracicaba (SP)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

The Piracicaba River s Basin is located in an urbanized and industrialized region. The downstream portion of the Piracicaba River was impounded and the reservoir sustained some riverine fishing communities along it s margins. This study analyses the fisheries in three Piracicaba river bank communities. Rua do Porto. Ponte de Santa Maria da Serra and Tanquã. within an ecological framework The research s objectives are: a) to compare the fishing activities among the three communities; b) to verify the fishery s dynamics in Ponte de Santa Maria and Tanquã. with regard to seasonality, productivity and species caught, c) to analyze fishermen s behavior using optimal foraging theory and d) to conduct an ethnoicthyological study focusing on fishermen s knowledge about behavioral and biological aspects of fish The residents in the three communities were interviewed with questionnaires. Fish landings were recorded monthly at Ponte de Santa Maria da Serra and Tanquã. between October 1994 and September 1995. Data were collected about the weight offish caught (Kg / species), the quantity of nets utilized (on square meters), the distance traveled at fishing sites (on kilometers and minutes) and net permanence in the water (on hours) In the ethnoicthvologial study fishermen were interviewed with questionnaires based on pictures of ten fishes species. The artisanal commercial fishery was sensibly reduced at Rua do Porto, possibly due to the environmental impacts in this river, represented principally by pollution and impoundment The majority of people living at the three localities sampled were conscious of the negative effects advanced by the pollution at the Piracicaba River The reservoir s formation was responsible by the nourishment of Ponte de Santa Maria s and Tanquã s fisheries, which explores a minor fish species diversity and utilizes fewer kinds of gear, compared with the Rua do Porto past fishery At Ponte de Santa Maria and Tanquã fishermen use almost exclusively gillncts. and their fishing strategies were influenced by the scasonalitv and migratory behavior of the corimbatá (Prochilodus lineatus). the main fish specie s caught Another important species captured were the corvina (Plagioscion squamosissimus), the mandi (mainly Pimeiodus maculatus), the cascudo (mainly Liposarcus anisitsi), the lamban (small fishes of Tetragonopterinac family) and the traíra (Hoptias malabaricus), corresponding together with the corimbatá to 90 % offish biomass landed The productivity of the fishery (weight offish caught per fishing trip) peaked at spring and summer, being more reduced at winter and fall, the season when the water s level was highest. The fish species composition of the catch varies among seasons and net s mesh sizes. The large sized mesh nets (10 to 20) were the most productive and very specialized, capturing mainly the corimbatá. The fishermen at Ponte de Santa Maria da Serra on average captured more fish and invested on more fishing effort than Tanquã s fishermen, probably due to a greater corimbatás abundance and more effective means of catch s commercialization on the first site. The central place optimal foraging theory was useful to analyze fishermen behavior: the positive relationship between distance traveled (in minutes) and weight of fish caught were strong for the lambari fishery. The Ponte de Santa Maria s and Tanquã s fishermen demonstered a detailed knowledge about fish diet, predators, spacial and temporal distributions, reproduction and migratory patterns. Various informations provided by fishermen with regard to these topics fitted quite well biological observations. Future impacts on the Piracacaba River Basin promoted by the lack of control regarding the organic waste, heavy metals and other pollutants discharges, a new dam construction to enhance the river s navigability, and clearance of riparian forests, arc serious threats to the fisheries of Ponte de Santa Maria da Serra and Tanquã

ASSUNTO(S)

pesca poluição ecologia humana

ACESSO AO ARTIGO

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