Efeito do co-manejo da pesca para a conservação de quelônios (Testudines, Podocnemididae) na várzea de Santarém, Pará, Brasil

Abstract

We investigated the effect of a fishing agreement in Santarem s whitewater floodplain on the relative abundance of Podocnemis spp turtles. We also analyzed the influence of environmental variables: i) depth of the sample point, ii) the area of the body of water, iii) river level and, iv) distance to the closest nesting beach on fishery s number of captures and captured biomass. We conducted 14 experimental capture excursions using gillnets during the lower water season, from August to October 2009. CPUE was calculated as the number of individuals captured (CPUEN = N/1000m2/24h) and as biomass captured (CPUEB = kg/1000m2/24h). Average CPUEN where the fishing agreement rules are not respected was 1.6 animals/1000m2/24h (sd = 1.8), and 13.5 N/1000m2/24h (sd = 9.3) where the fishing agreement is respected. Average CPUEB in these locations was 20.2 kg/1000m2/24h (sd = 11.7), higher than the average 3.4 kg/1000m2/24h (sd = 2.6) where the rules are not observed. The effects of environmental variables and the categorical variable respect of the fishing agreement on the CPUEN and CPUEB were tested by Analysis of Covariance. The full model accounted for 89% of the variation in CPUEN, with significant effect of the distance to the nesting beach. For the CPUEB, the full model accounted for 87.5% of the variation, with significant effect of the fishing agreement. The sample points where the fishing agreement is respected were significantly deeper than those where the fishing agreement is not respected. Thus, the effect of depth on turtle capture need to be more studied. Depth may influence the effectiveness of the fishing agreement and this deserve more studies as well. The main rule of this fishing agreement is the prohibition of gillnets during the low water period, when fish are concentrated in lakes and easier to catch. Traditional turtle capture is intimately related to routine fisheries. This Fishing Agreement can result in a positive effect on the Podocnemis spp. turtles mainly by protecting the adults and subadults during the reproductive period, when they are most captured. Turtle consumption is a traditional practice of Amazonian people and its rational management may be an important tool to amazon turtle conservation.