OVERVIEW OF SEABIRD BYCATCH BY BRAZILIAN FISHERIES IN THE SOUTH (original) (raw)
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OVERVIEW OF SEABIRD BYCATCH BY BRAZILIAN FISHERIES IN THE SOUTH ATLANTIC OCEAN
The impact of fisheries bycatch on seabirds around the world is currently the focus of considerable international concern. In Brazilian waters there are eight fisheries that affect seabirds, according to the National Plan of Action for the Conservation of Albatrosses and Petrels (NPOA-Seabirds Brazil). Capture rates obtained by observers during 40 cruises (473 sets and 499,978 hooks) in the pelagic longline fisheries in south and southeastern areas, between November 2000 and December 2005 were 0.102 birds/1000 hooks. The leased fleet (based in northern and northeast ports) that fished along most of the Brazilian coast and in adjacent international waters was sampled by ProBordo observers (Brazilian National Observer Program). Seabird capture in this fishery during 2005 was 68 specimens. The most commonly captured species in both the leased and domestic fleets were the black-browed (Thalassarche melanophris) and Atlantic yellow-nosed (T. chlororhynchos) albatrosses, whitechinned (Procellaria aequinoctialis), spectacled (P. conspicillata) petrels and the great shearwater (Puffinus gravis). Other fisheries have demonstrated that fishing is an important mortality factor for seabirds and incidental capture rates must be evaluated. The assessment of seabird by-catch by fleets based in Brazilian ports must continue in order to support the implementation of mitigation measures.
2008
The Southwestern Atlantic Ocean is an important foraging ground for several albatrosses and petrels during breeding and non-breeding seasons. In this region they meet longline fishing fleets, currently the main threat for this group of seabirds. Significant overlap between longline fishery and seabird distribution in southern Brazil, especially during winter, is the major cause for concern. Here we present information on bycatch rates of seabirds in the Brazilian domestic pelagic longline fleet from 2001 to 2007 on the Exclusive Economic Zone (EEZ) and adjacent international waters of the Southwestern Atlantic Ocean and a review of bycatch rates reported for the area. Overall seabird capture rates obtained during 63 cruises (656 sets and 788,446 hooks) was 0.229 birds/1000 hooks, varying from zero to 0.542 birds/1000 according to season. Capture rates were higher between June and November (cold season) and affected mainly black-browed albatross Thalassarche melanophris (55% of birds captured), white-chinned petrel Procellaria aequinoctialis, spectacled petrel Procellaria conspicillata and Atlantic yellow-nosed albatross Thalassarche chlororhynchos. Capture rates previously reported in SW Atlantic varied from 0 to 5.03 birds/1000 hooks, with those based on logbooks or fishermen interview tending to underestimate capture rates, whereas those based on small number of hooks and/or seasonally biased tend to overestimated in both pelagic and demersal longline fisheries. Representative capture rates for the pelagic longline are in the range of 0.2 to 0.4 birds/1000 hooks. Detailed studies with large sample sizes are required for a comprehensive approach of causes determining the incidental capture.
Endangered Species Research, 2008
Appendix 1. Summary of studies reporting capture rates of seabirds (birds per 1000 hooks) in demersal and pelagic longline fisheries in the southwestern Atlantic Ocean from 1991 to 2008. -: data not provided. Range of capture rates was reported in several ways, e.g. between sets, cruises, season or areas. Namorado = Pseudopercis numida, tilefish = Lopholatilus villarii, groupers = Epinephelus spp., toothfish = Dissostichus eleginoides, hake = Merluccius hubbsii, kingclip = Genypterus blacodes, tunas = Thunnus spp., swordfish = Xiphias gladius, sharks = several species, including Prionace glauca, Sphyrna spp., Carcharhinus spp., and Alopias spp.), wreckfish = Polyprion americanus, yellownosed skate = Dipturus chilensis, dolphinfish = Coryphaena hippurus Longline type Location Mean capture rate Range capture rate Year(s)
Global Ecology and Conservation, 2015
Competition with fisheries and incidental capture in fishing gear are the major current threats for seabirds at sea. Fishing is a traditional activity in Portugal and is mainly composed of a great number of small vessels. Given the lack of knowledge on effects of the Portuguese fishing fleet on seabird populations, bycatch was assessed in mainland coastal waters for 2010-2012. Interviews and on-board data were divided into 5 strata, according to fishing gear: Bottom trawling, Bottom longline, Purse seine, Beach seine, Polyvalent (≥12 m) and Polyvalent (<12 m). Polyvalent included Setnets, Traps and Demersal longlines. Overall, 68 birds were recorded to be bycaught. The average catch per unit effort (CPUE) was 0.05 birds per fishing event. Polyvalent (<12 m), Polyvalent (≥12 m) and Purse seiners had the biggest seabird bycatch rates, with 0.5 (CPUE = 0.1), 0.11 (CPUE = 0.05) and 0.2 (CPUE = 0.11) birds per trip, respectively. Within Polyvalent gear, Setnets captured the largest diversity of seabird species (CPUE = 0.06), while Demersal longline had the highest CPUE (0.86). Northern gannet was the most common bycaught species. Although more observation effort is required, our results suggest that substantial numbers of Balearic shearwater might be bycaught annually, mainly in Purse seine and Setnets.
Potential bycatch of seabirds and turtles in hook-and-line fisheries of the Itaipava Fleet, Brazil
Fisheries Research, 2008
The decline of populations of certain seabirds and sea turtles around the world is partly related to their incidental capture in large-scale fisheries. However, the impacts of small-scale fisheries on endangered seabirds and sea turtles, being carried out in many places around the world, have been largely neglected by scientists and governments. We monitored 178 fishing days and described a range of poorly known hook-and-line commercial fisheries carried out by the Itaipava fleet, southeastern Brazil, composed by 497 vessels and deploying hooks from 18 • S to 35 • S. Seven fisheries were defined: fast trolling for tuna and tuna-like species, slow trolling for Bigeye tuna, handlining, surface longline for Dolphinfish, pelagic longline for Swordfish, bottom dropline, and pole-and-line with live bait. We observed bycatch of 47 seabirds of six species and 45 turtles of four species. Capture rates were higher for the surface longline for Dolphinfish (0.15 birds/1000 hooks and 1.08 turtles/1000 hooks), slow trolling for Bigeye tuna (0.41 birds/day) and handlining targeting Yellowfin tuna (0.61 birds/day). Endangered Spectacled petrel (Procellaria conspicillata), Atlantic Yellow-nosed (Thalassarche chlororhynchos), and Black-browed (T. melanophris) albatrosses were the main seabirds caught. Immature Loggerhead turtles (Caretta caretta) and immature or adult Leatherback turtles (Dermochelys coriacea) were the main sea turtles affected by the surface longline for Dolphinfish. Monitoring the fleet and bycatch levels, development of mitigation measures, establishment of educational programs, government control over the fleet, and enforcement, are urgently required for the hook-and-line fisheries described in the present study.
Seabirds attending bottom long-line fishing off southeastern Brazil
Ibis, 1997
Flocks of seabirds attending commercial bottom long-line fishing operations on the coastal shelf off southeastern Brazil show a greater species diversity during the summer than the winter (16 v 9 species), although the number of birds per flock tended to be greater during the cold season. During the summer, the Spectacled Petrel Procellaria aequinoctialis conspi-cillata was the commonest species, followed by the Great Shearwater Puffinus gravis, Cory's Shearwater Calonectris diomedea, skuas Stercorarius spp. and the Yellow-nosed AlbatrossDiomedea chlororhynchus. During the winter, the White-chinned Petrel Procellaria aequin-octialis, Yellow-nosed Albatross and Black-browed Albatross Diomedea melanophrys were jointly the commonest species. Marked differences in the relative abundance of species were observed between the different sampling periods, probably because of migratory movements but also because of seasonal shifts of the sea currents and the influence of cold fronts. Waters off southeastern Brazil are important feeding areas for some seabird populations nesting in the Tristan da Cunha and Gough group, especially for nonbreeding Spectacled Petrels and post-breeding Yellow-nosed Albatrosses.
Estimates of seabird incidental catch by pelagic longline fisheries in the South Atlantic Ocean
Animal Conservation, 2013
The mortality of seabirds in fisheries has had a serious negative impact on many seabird populations, yet the extent of fishery-derived seabird mortality in pelagic longline fisheries, remains poorly understood. In this study, we analyze fishing effort and catch data of the Taiwanese distant-water longline tuna fleet -the largest fleet in the Atlantic Ocean. These data collected by fishery observers over a 5-year span include 61 trips involving 6181 observed sets of over 20 million hooks, where 198 seabirds were caught (23 of which were released alive). Most birds were caught in the South Atlantic, with estimated seabird bycatch rates ranging from 0.026 birds per thousand hooks in the southwest Atlantic to 0.063 birds per thousand hooks in the southeast Atlantic. Black-browed, Atlantic yellow-nosed, and wandering albatrosses, as well as spectacled and southern giant petrels, were the most frequently caught species. Seabird bycatch hotspots were identified at 20°-40°S/10°W-15°E and 35°-45°S/45°-55°W. In the South Atlantic Ocean, generalized additive models indicated that fishing location and the number of birds sighted significantly influenced seabird bycatch rates. Extrapolating these spatially and temporally explicit seabird bycatch rates to the fishing effort data of other distant-water longline fleets and extrapolating the bycatch rates reported in the literature to the reported fishing effort of coastal nation fleets, we estimate the total seabird incidental mortality from pelagic longline fishing in the southern Atlantic Ocean to be between 3446 and 6083 birds per year from 2004 to 2008. These findings support proposals calling for the required use of best-practice mitigation measures by all pelagic longline vessels operating in seabird bycatch hotspots in the South Atlantic Ocean. International cooperation on research and data sharing is critical to ensure the sustainability of seabird populations and fisheries. Seabird bycatch in the South Atlantic Ocean Y-M. Yeh et al. Y-M. Yeh et al.
Aquatic Living Resources, 2010
The black-browed (Thalassarche melanophrys) and Atlantic yellow-nosed (Thalassarche chlororhynchos) albatrosses and the white-chinned petrel (Procellaria aequinoctialis) are the seabird species most frequently captured by pelagic longline fisheries in the southwest Atlantic. This study estimates this type of bycatch and describes the spatialtemporal patterns of the incidental capture of these species by the Uruguayan pelagic longline fleet, based on data collected by scientific observers on 47 fishing trips from 2004 to 2007. Three generalized linear models (GLM) models were employed to predict bycatch for each species based on the observed data. We also developed a spatio-temporal species-specific analysis. Captures were recorded in Uruguayan waters, mainly over the slope and depth waters, and in international waters adjacent to Uruguay, the north of Argentina, and the south of Brazil. The highest catch rates for black-browed albatrosses and white-chinned petrels were recorded on the Uruguayan slope from fall to spring, while the highest values for Atlantic yellow-nosed albatrosses were recorded further to the north, in the international waters off Brazil in late winter. The average estimated number of black-browed and Atlantic yellow-nosed albatrosses and white-chinned petrels caught during the study period was 1683, 257 and 239 birds, respectively. Taking into account the total effort of the fleet, these values represent an estimated catch rate of 0.276, 0.042, and 0.039 birds/1000 hooks for these species, respectively. The results of the present study suggest that the annual impact of this fishery is medium to high on the black-browed albatross, low on the Atlantic yellow-nosed albatross and low on the white-chinned petrel. However, the situation of these species in the southwest Atlantic should be viewed with considerable concern, as our understanding of the impact of the bycatch on their populations requires more research. Any effort to reduce seabird mortality in the southern hemisphere should target this geographic region.
Incidental capture of seabirds in Argentinean side-haul trawlers
Bird Conservation International, 2020
SummaryBetween April 2008 and July 2015, we conducted a total of 18 trips on five different side-haul trawlers fishing within the Argentine Exclusive Economic Zone, monitoring 486 hauls. We observed 100% of the hauls and monitored trawl cables for 136.7 hours, about 5% of the trawl effort, to identify the levels of seabird bycatch from net entanglements and collisions with trawl cables. A total of 35 net entanglements of White-chinned Petrels Procellaria aequinoctialis, Great Shearwaters Ardenna gravis, Black-browed Albatrosses Thalassarche melanophris and Southern Royal Albatross Diomedea epomophora were recorded, all of which occurred during the autumn and winter. Additionally, 656 seabird collisions against trawl cables were recorded including 39 heavy, 96 medium and 521 light. Further, we recorded nine Black-browed Albatrosses and two Great Shearwaters potentially dead. Although in the study fishery the number of deaths in the trawl cables could surpass the number of birds incid...