Analise das estrategias da pesca do camarão de São Francisco, São Sebastião-SP : pela Teoria do Forrageio Otimo / Analysis of the strategies of shrimp fishing in São Francisco, São Sebastião-SP : through the Optimal Foraging Theory

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This study uses ecological models derived from the Optimal Foraging Theory (OFT) to understand the decision-making processes among bottom trawling shrimp fishermen at the São Francisco Neighborhood, in the district of São Sebastião, SP, Brazil. Using the theoretical background of Human Behavioral Ecology the aim of this work was to analyze fishermen s strategies using OFT models to raise hypotheses about the smallscale fisheries activity. Taking into consideration benefits and costs associated to the foraging behavior (search, capture, handling, and consumption), models derived from OFT predict the most economic behavior of the foraging animal. In this work we tested two main hypotheses: 1) the further the fishing ground, the longer the time fishermen will stay fishing, and consequently, the higher the return obtained; 2) fisherman will choose the fishing ground according to the last trip s return. Sampling methods consisted basically in closed-end questionnaires and direct observations made during fishing landings (N=77). Fishing landing activities of 28 fishermen were registered during 22 consecutive days (from April 16th until May 7th, 2008) at the main landing point of São Francisco neighborhood. Shrimp represented 76.04% of the 6,766 Kg total landed. Among them, the most captured species were sea bob shrimp (Xiphopenaeus kroyeri) and the white shrimp (Litopenaeus schmitti). Fishermen used 19 different fishing grounds during the period studied. As predicted by OFT, fishermen trawled longer when they traveled to further fishing grounds, obtaining higher returns (money and biomass). The average gross return rate of the fishing grounds was a good parameter to evaluate different decisions concerning fishing ground choices. When the return rate of the previous trip was below the average, fishermen changed the fishing ground more often, returning to the same fishing ground more frequently when the return rate of the previous was above the average (?2= 4.7; p<0.05; n=49; df=1). Fishermen s decisions concerning the choice of fishing grounds were based on previous trips experiences, on a daily base. In addition, fishermen are exploiting local resources as efficiently as they can, maximizing the short term financial return. This behavior can lead to resource depression in the long term, thus it is very important to build local management strategies. Methods used to test OFT hypotheses provide important information about fishing grounds use, for example, which can be used to guide the choice of no-take areas (refugees) when developing management strategies

ASSUNTO(S)

forrageio foraging fishery mangement ecological model pescadores ecologia humana fishermen manejo pesqueiro modelo ecologico human ecology

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