Croxall J.,Global Seabird Programme |
Small C.,Royal Society for the Protection of Birds |
Sullivan B.,Royal Society for the Protection of Birds |
Wanless R.,BirdLife South Africa |
And 6 more authors.
Marine Ecology Progress Series | Year: 2013
Torres et al. (2013; Mar Ecol Prog Ser 473:275-289) use fine-scale data on tracked locations of one species of albatross and fishing vessels to make a variety of assertions on interactions between them, especially in relation to risk of bycatch. Some of these assertions are incorrect, and we seek to clarify the issues and perspectives involved. We argue that while a fine-scale approach can provide interesting insights into foraging behaviour, large-scale risk analysis is needed because management measures (e.g. for bycatch mitigation) need to operate across all vessels in a fishery and across all seabird species at risk from the fishing operation. In addition, an estimate of 10% time spent in close proximity to vessels cannot be used to infer low bycatch risk alone: such an inference would need comparison to bycatch rate data. The analysis also does not take into account a number of factors known to affect the nature and duration of the association of albatrosses with fishing vessels, which limits the conclusions that can be drawn. However, finescale studies can provide important insight into factors affecting individual bycatch events, and studies at fine and broad scales will be complementary. © Inter-Research 2013.
Sullivan B.J.,BirdLife International Global Seabird Programme |
Kibel P.,Fishtek |
Robertson G.,Australian Antarctic Division |
Kibel B.,Fishtek |
And 3 more authors.
Fisheries Research | Year: 2012
In many pelagic longline fisheries around the world there is reluctance to adopt a line weighting regime that will sink fishing gear rapidly to reduce seabird bycatch. In many cases this is due to safety concerns caused by traditional leaded swivels causing serious injuries, and even fatalities, when they fly-back at the crew in the event of line breakage (e.g. from shark bite offs) during line hauling. This paper presents the results of at-sea and on-shore trials to test the safety and operational effectiveness of an alternative line weight (the Safe Lead) which is designed to slide down, or off the line, in the event of a bite-off, significantly reducing danger to the crew from line weights. At-sea trials in South Africa revealed that Safe Leads can reduce the incidence of dangerous fly-backs to very low levels. In at-sea trails, only 4.2% of Safe Lead fly-backs reached the vessel (the remainder fell in the sea) whereas 73.3% of fly-backs by leaded swivels hit the vessel and one hit a crewmen in the head. Simulated bite-off events on shore revealed the degree of slippage (influences whether leads slide but remain on the branch line, or slide off the end of the line) varied as a function of distance from Safe Lead to hook (1-4. m range) and tension on the line (20-120 kg range). All Safe Lead replicates placed within 2. m of the hook slid off the line under all four tension treatments. Under the higher tension categories of 80 kg and 120 kg, 80% of Safe Leads positioned 3. m from the hook position slid off the line after a simulated bite-off (cut-away). High speed photography of fly-backs showed a significant (P<0.05) reduction in the velocity on impact of Safe Leads compared to leaded swivels and an associated >80% reduction in kinetic energy on impact. Our results suggest that Safe Leads are a cost-effective and operationally simple alternative to traditional leaded swivels with significant benefits to crew safety. © 2012 Elsevier B.V.
Reid E.,BirdLife International Global Seabird Programme |
Sullivane B.,BirdLife International Global Seabird Programme |
Clark J.,MRAG Ltd
CCAMLR Science | Year: 2010
In recent years there has been an increased focus on reducing seabird captures that occur during hauling in CCAMLR longline fisheries. Haul captures were first recognised by CCAMLR as a problem as early as 1994/95 when steps were taken to reduce the attraction of seabirds to vessels during the hauling process. Since 2003, increased efforts have been made to improve the design and performance of bird exclusion devices (BEDs) placed around the hauling bay. Data collected by scientific observers since 2003 suggest that there are two key aspects of effective BEDs, firstly that they provide a deterrent to seabirds landing adjacent to the line as it is being hauled, and secondly that seabirds are deterred from swimming or 'jumping' into the area around the hauling bay. Based on this analysis, CCAMLR incorporated these two key functional characteristics into the specification of a BED to be deployed by longline vessels to reduce seabird captures during the haul.
Anderson O.R.J.,BirdLife International Global Seabird Programme |
Small C.J.,BirdLife International Global Seabird Programme |
Croxall J.P.,BirdLife International Global Seabird Programme |
Dunn E.K.,BirdLife International Global Seabird Programme |
And 3 more authors.
Endangered Species Research | Year: 2011
Bycatch in longline fisheries is believed to govern the adverse conservation status of many seabird species, but no comprehensive global assessment has been undertaken. We reviewed the extent of seabird bycatch in all longline fisheries for which data are available. Despite the many inadequacies and assumptions contained therein, we estimated that at least 160 000 (and potentially in excess of 320 000) seabirds are killed annually. Most frequently caught are albatrosses, petrels and shearwaters, with current levels of mortality liable to be unsustainable for some species and popula- tions. Where realistic comparisons can be made, with data from the 1990s, there is evidence of sub- stantially reduced bycatch in some key fisheries. Reductions stem from decreased fishing effort (especially in illegal, unreported and unregulated fishing in the Southern Ocean), and greater and more effective use of technical mitigation measures, notably in demersal fisheries. However, bycatch problems in other fisheries have also emerged. Current concerns include those with previously unidentified bycatch problems (e.g. Spanish Gran Sol demersal fleet) and those where bycatch was identified, but where persistent data gaps prevented adequate assessments of the scale of the impact (e.g. Nordic demersal fisheries). Future assessments will only achieve greater precision when mini- mum standards of data collection, reporting and analysis are implemented by longline fishing fleets and the relevant regional fishery management organisations. Those fisheries in which bycatch has been substantially reduced demonstrate that the problem of seabird bycatch could be reduced to negligible proportions by enforced implementation of appropriate best-practice mitigation devices and techniques. © Inter-Research 2011.
Zydelis R.,DHI |
Small C.,BirdLife International Global Seabird Programme |
French G.,BirdLife International Global Seabird Programme
Biological Conservation | Year: 2013
Based on bird feeding ecology we identified 148 seabird species as susceptible to bycatch in gillnets, of which 81 have been recorded caught. The highest densities of susceptible species occur in temperate and sub-polar regions of both hemispheres, with lower densities in tropical regions. Gillnet fisheries are widespread and particularly prevalent in coastal areas. A review of reported bycatch estimates suggests that at least 400,000 birds die in gillnets each year. The highest bycatch has been reported in the Northwest Pacific, Iceland and the Baltic Sea. Species suffering potentially significant impacts of gillnet mortality include common guillemot (Uria aalge), thick-billed guillemot ( Uria lomvia), red-throated loon ( Gavia stellata), Humboldt penguin (Spheniscus humboldti), Magellanic penguin ( Spheniscus magellanicus), yellow-eyed penguin (Megadyptes antipodes), little penguin (Eudyptula minor), greater scaup (Aythya marila) and long-tailed duck (Clangula hyemalis). Although reports of seabird bycatch in gillnets are relatively numerous, the magnitude of this phenomenon is poorly known for all regions. Further, population modelling to assess effects of gillnet bycatch mortality on seabird populations has rarely been feasible and there is a need for further data to advance development of bycatch mitigation measures. © 2013 Elsevier Ltd.