Multiple strategies developed by bottom trawlers to exploit fishing resources in deep areas off Brazil

Abstract

Since the early 2000s, codling, hake and blackfin goosefish became main components in the landings of double-rig and stern trawlers fishing in the slope off the south and southeast coasts of Brazil. Because these stocks are known to be little resilient, the heterogeneous and unpredictable fishing regime has been regarded as biologically and ecologically unsafe. In this article, we examine the fishing strategies developed by the Brazilian trawl fleet when fishing deep water fish between 2007 and 2009. Slope fish resources were primarily exploited under four fishing tactics. On Tactic 1 landings comprised mainly hake and blackfin goosefish, with trawlers concentrating their fishing effort on the fishing grounds located in the upper slope (300- 350 m depth) in central and northern areas. Two other strategies (Tactics 3 and 4) were similar to each other, with trawlers occupying fishing grounds on the upper slope (350 m) along the whole area. Catches were dominated by codling, representing at least 50% of the fish landed. A fourth strategy (Tactic 2) concentrated in shallow fishing grounds (100 m) along the whole coast, reported only small landings of deep water species (less than 20%). We characterized five different fleets based on the number of fishing trips that vessels dedicated to each strategy. During the study period, 34-37 vessels have undertaken fishing trips primarily in slope fishing grounds, however a few vessels (10-14) also fished for coastal species (Tactic 2). From 11 to 22 vessels fished regularly as coastal trawlers, operating opportunistically on slope grounds. Management of the deep water trawl fishery should take into consideration the number of trawlers specialized in targeting deep-water resources and the behaviour of opportunistic trawlers occasionally fishing in the slope.