Preliminary Analysis of the Feasibility of Transferring New Longline Technology to Small Artisanal Vessels off Northeastern Brazil

The catches of three long­ liners, including two recently converted small artisanal vessels and one large leased foreign longliner, were compared to provide some indication of the feasibility of transfer­ ring new longline technology to small ves­ sels in the northeastern Brazilian pelagic longline fishery. Comparisons of catches between the two recently converted vessels operating across the same spatial and tem­ poral scales showed no significant differ­ ences for the main target species, providing evidence to suggest that adoption of the tech­ nology was rapid and straightforward. A comparison of relative catch rates between one of the recently converted small long­ liners and the leased longliner across the same temporal scale, but in different areas, showed that while there were significant differences detected for some species, con­ tributing to a significant reduction in total CPUE, the relative abundance of commer­ cially important species within the oper­ ational range of the smaller vessels was sufficient for economically viable catches. The results showed that the net financial profit from the artisanal longliner was almost 10 times greater than that derived from existing fishing methods. The inclusion of some artisanal vessels in this fishery may help address the social and economic prob­ lems currently faced by fishing communities in northeastern Brazil. their exploitation. Most fishing occurs within 20 km of the coast using small simple wooden vessels (6–12 m), pow­ ered by 3or 4-cylinder diesel motors, and includes handlining for benthic species of fish (i.e. snappers, Lutjanus spp.; weakfish, Cynoscion spp.; and groupers, Mycteroperca spp.) and more commonly, the use of gillnets and baited bamboo traps to target spiny lobsters (Panulirus argus and P. laevi­ cauda) (Paiva et al., 1971). No regu­ lation of fishing effort, combined with recruitment failures due to degradation of nursery areas and over fishing, has meant that most stocks are currently ex­ ploited well beyond sustainable levels (Dias Neto and Dornelles, 1996). A steady decline in catches over the past 20 years has resulted in serious social and economic conditions for many fish­ ing communities (Dias Neto and Dor­ nelles, 1996). In an attempt to improve local con­ ditions, during the early 1980’s some operators began to investigate alter­ native fishing methods and, in partic­ ular, pelagic longlines to target stocks of highly migratory oceanic groups of species such as tunas (Scombridae), sharks (Carcharhinidae), and billfishes (Istiophoridae and Xiphiidae). A main contributing factor toward investment in this method was the result of earlier exploratory fishing by leased Japanese longliners operating (from the mid 1950’s to 1964) throughout the equa­ torial Atlantic Ocean. Several large (18 m) artisanal vessels from Natal were modified to include Japanese-style mutifilament longlines (details provid­ ed by Suzuki et al., 1977; Hazin et al., 1998) and in 1983 began fishing for tuna (mostly yellowfin tuna, Thunnus albacares). By 1996, this fleet had ex­ panded to 10 vessels and although there were several shifts in effort on target species during this period (mainly mar­ ketoriented and owing to the discov­ ery of new fishing grounds and stocks), few technological advancements in the types of gears used meant that total catch per unit of effort (CPUE = number of fish caught/100 hooks/day) remained fairly stable at about 2.4 (Hazin et al., 1994b, 1998). While these catches appear quite low, they are comparable to many other pe­ lagic longline fisheries throughout the world (Kawaguchi, 1974; Sakagawa et al., 1987; Uozumi, 1996) and are indic­ ative of the static nature of the fishing gear and low density and foraging be­ havior of target species. The effective­ ness of pelagic longlines is determined by several interrelated factors including the type, size, and spacing of hooks; vertical distribution in relation to maxi­ mum abundance of target species; set­ ting time and direction; and, perhaps most importantly, the stimuli associ­ ated with bait (Bjordal, 1989; Løkke­ borg and Bjordal, 1992; Løkkeborg and Pina, 1997). The integration of these factors in the pelagic longline fishery off northeastern Brazil means that to provide profitable catches, vessels typi­ cally have been required to set at least 1,200 hooks over 35 km of mainline. The logistics of manually operating such gear effectively have limited the size of vessels to a minimum of 18 m, precluding adoption of this fishing method by smaller and more common­ sized artisanal vessels of between 8 and 12 m.