Proposta de zoneamento da pesca de arrasto da piramutaba Brachyplatysíoma vaillantii na costa norte do Brasil.

Abstract

In this zoning proposal for industrial fishing for piramutaba trawl {Brachyplatystoma vaillaníii), two different data sources were used: data from the PREPS (National Satellite Fishing Vessel Tracking Program) relating to piramutabeira vessels on the northem coast of Brazil, from 2008 to 2011 and productivity data of the on-board maps of this fishery (between February 2008 and September 2011). PREPS s tracking methodology allows remote monitoring of fishing vessels. The system presents a series of information regarding the geographical positioning and displacement offishing vessels operating in Brazil. The records related to fishing activity showed three large areas with density concentrations, in terms of occupation by intensity of use of area, well marked in the four years studied and geographically understood between the parallels from 00oN to 01oN, 01oN to 02oN, 00oN to 01oN and the meridians from 048o40W to 049o40W, 048o40W to 049o40W and 047o40W to 048o40, respectively. These fishing zones were divided into quadrants and delimited as Rotating Protection Area (APR). A four-monthly fishing cycle was suggested, consisting of three quadrants (fishing activity) 4 months in each area and 8 months rest for stock recovery. For the onboard map data, information on 10,467 fishing throws were evaluated and the average CPUE for each month of the year was calculated. According to the flow data obtained through the portal of the National Water Agency - ANA, from the station located in the municipality of Óbidos, PA and from the results of the analysis of the data, the highest CPUE values were verified in the period of greatest flow of the Amazon River: May to June 2008 (340.06 kg/hdec-nets), April to July 2009 (298.26 kg/hdec-nets) and May to June 2010 (439.25 kg/hdec-nets). The CPUE results were also related to the monthly average rainfall of the Northeast Pará stations (mm), monthly average Amazon river flow (m3/s) and the El Nino 3.4 index using cross-correlation analysis. The average monthly variation ofpiramutaba CPUE based on the Lomb Periodogram showed a well marked and constant cycle of approximately one year. Among the environmental factors that possibly influenced this cycle, the El Nino 3.4 index was negatively correlated (r =-0.77; p <0.001), 15 months, while the monthly rainfall and the average flow of the Amazon River showed significant and strongly positive correlations. (r =0.89 and 0.87; p<0.001), with lags of 12 and 11 months, respectively. Thus, it can be explained that fluctuations in the average CPUE variation per month of piramutaba wereinfluenced by weather events. Finally, in La Nina years, it is expected that there will be an increase in rainfall and flow and consequently the capture of piramutaba on the northern coast of Brazil.