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Seabird mortality in the Namibian demersal longline fishery and recommendations for best practice mitigation measures

  • John R. B. Paterson (a1), Oliver Yates (a2), Hannes Holtzhausen (a3), Tim Reid (a4), Kaspar Shimooshili (a5), Sarah Yates (a1), Benedict J. Sullivan (a2) and Ross M. Wanless (a4)...
Abstract

Seabird bycatch is widely regarded as the greatest threat globally to procellariiform seabirds. Although measures to reduce seabird–fishery interactions have been in existence for many years, uptake in fleets with high risk profiles remains variable. We recorded seabird bycatch and other interactions in the Namibian demersal longline fishery. Interaction rates were estimated for seasonal and spatial strata and scaled up to fishing effort data. Bycatch rates were 0.77 (95% CI 0.24–1.39) and 0.37 (95% CI 0.11–0.72) birds per 1,000 hooks in winter and summer, respectively. Scaling up to 2010, the most recent year for which complete data are available, suggests 20,567 (95% CI 6,328–37,935) birds were killed in this fishery that year. We compared bycatch rates to those from experimental fishing sets using mitigation measures (one or two bird-scaring lines and the replacement of standard concrete weights with 5 kg steel weights). All mitigation measures significantly reduced the bycatch rate. This study confirms the Namibian longline fishery has some of the highest known impacts on seabirds globally, but implementing simple measures could rapidly reduce those impacts. In November 2015 the Ministry of Fisheries and Marine Resources introduced regulations requiring the use of bird-scaring lines, line weighting and night setting in this fishery. A collaborative approach between NGOs, industry and government was important in achieving wide understanding and acceptance of the proposed mitigation measures in the lead up to the introduction of new fishery regulations.

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(Corresponding author) E-mail oli.yates@rspb.org.uk
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Current address: 6433 Seaforth Street, Halifax, Nova Scotia B3L 1R4, Canada

Also at: Institute for Applied Ecology, University of Canberra, ACT 2617, Australia

Also at: Seabird Conservation Programme, BirdLife South Africa, Roggebaai, South Africa

Footnotes
References
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ACAP (2014) Report of the Sixth Meeting of the Seabird Bycatch Working Group. Unpublished report. ACAP, Punta del Este, Uruguay.
ACAP (2017) Agreement on the Conservation of Albatrosses and Petrels. Http://acap.aq/ [accessed 23 February 2017].
Agnew, D.J., Black, A.D., Croxall, J.P. & Parkes, G.B. (2000) Experimental evaluation of the effectiveness of weighting regimes in reducing seabird by-catch in the longline toothfish fishery around South Georgia. CCAMLR Science, 7, 119131.
Anderson, O.R., Small, C.J., Croxall, J.P., Dunn, E.K., Sullivan, B.J., Yates, O. & Black, A. (2011) Global seabird bycatch in longline fisheries. Endangered Species Research, 14, 91106.
Ashford, J.R., Croxall, J.P., Rubilar, P.S. & Moreno, C.A. (1995) Seabird interactions with longlining operations for Dissostichus eleginoides around South Georgia, April to May 1994. CCAMLR Science, 2, 111122.
Bates, D., Maechler, M., Bolker, B. & Walker, S. (2015) Fitting linear mixed-effects models using lme4. Journal of Statistical Software, 67, 148.
BirdLife International (2016a) Procellaria aequinoctialis. In The IUCN Red List of Threatened Species 2016: e.T22698140A104916768. Http://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T22698140A104916768.en [accessed 23 February 2017].
BirdLife International (2016b) Species factsheet: White-chinned petrel Procellaria aequinoctialis. Http://www.birdlife.org [accessed 24 November 2016].
Brothers, N. (1991) Albatross mortality and associated bait loss in the Japanese longline fishery in the Southern Ocean. Biological Conservation, 55, 255268.
Brothers, N., Cooper, J.P. & Løkkeborg, S. (1999) The Incidental Catch of Seabirds by Longline Fisheries: Worldwide Review and Technical Guidelines for Mitigation. FAO Fisheries Circular No. 937. FAO, Rome, Italy.
Bull, L.S. (2007) Reducing seabird bycatch in longline, trawl and gillnet fisheries. Fish and Fisheries, 8, 3156.
Cherel, Y., Weimerskirch, H. & Duhamel, G. (1996) Interactions between longline vessels and seabirds in Kerguelen waters and a method to reduce seabird mortality. Biological Conservation, 75, 6370.
Croxall, J.P., Butchart, S.H.M., Lascelles, B., Stattersfield, A.J., Sullivan, B., Symes, A. & Taylor, P. (2012) Seabird conservation status, threats and priority actions: a global assessment. Bird Conservation International, 22, 134.
Croxall, J.P., Rothery, P., Pickering, S.P.C. & Prince, P.A. (1990) Reproductive performance, recruitment and survival of wandering albatrosses Diomedea exulans at Bird Island, South Georgia. Journal of Animal Ecology, 59, 775796.
FAO (1999) International Plan of Action for Reducing Incidental Catch of Seabirds in Longline Fisheries. Http://www.fao.org/fishery/ipoa-seabirds/en [accessed 9 October 2015].
FAO (2008) Report of the Expert Consultation on Best Practice Technical Guidelines for IPOA/NPOA–Seabirds. FAO Fisheries and Aquaculture Report. No. 880. FAO, Bergen Norway.
Furness, R.W. (2003) Impacts of fisheries on seabird communities. Scientia Marina, 67, 3345.
Gelman, A., Carlin, J.B., Stern, H.S., Dunson, D.B., Vehtari, A. & Rubin, D.B. (2014) Bayesian Data Analysis. 3rd edition. CRC Press, New York, USA.
Gordoa, A. & Macpherson, E. (1991) Diurnal variation in the feeding activity and catch rate of cape hake (Merluccius capensis and M. paradoxus) off Namibia. Fisheries Research, 12, 299305.
Jiménez, S., Domingo, A., Abreu, M. & Brazeiro, A. (2012) Bycatch susceptibility in pelagic longline fisheries: are albatrosses affected by the diving behaviour of medium-sized petrels? Aquatic Conservation: Marine and Freshwater Ecosystems, 22, 436445.
Jiménez, S., Domingo, A. & Brazeiro, A. (2009) Seabird bycatch in the Southwest Atlantic: interaction with the Uruguayan pelagic longline fishery. Polar Biology, 32, 187196.
Løkkeborg, S. (2003) Review and evaluation of three mitigation measures—bird-scaring line, underwater setting and line shooter—to reduce seabird bycatch in the north Atlantic longline fishery. Fisheries Research, 60, 1116.
Løkkeborg, S. (2011) Best practices to mitigate seabird bycatch in longline, trawl and gillnet fisheries—efficiency and practical applicability. Marine Ecology Progress Series, 435, 285303.
Mackley, E.K., Phillips, R.A., Silk, J.R.D., Wakefield, E.D., Afanasyev, V. & Furness, R.W. (2011) At-sea activity patterns of breeding and nonbreeding white-chinned petrels Procellaria aequinoctialis from South Georgia. Marine Biology, 158, 429438.
Maree, B.A., Wanless, R.M., Fairweather, T.P., Sullivan, B.J. & Yates, O. (2014) Significant reductions in mortality of threatened seabirds in a South African trawl fishery. Animal Conservation, 17, 520529.
Melvin, E.F., Parrish, J.K., Dietrich, K.S. & Hamel, O.S. (2001) Solutions to Seabird Bycatch in Alaska's Demersal Longline Fisheries. Unpublished report. Washington Sea Grant Program, Seattle, USA.
Melvin, E.F., Sullivan, B., Robertson, G. & Wienecke, B. (2004) A review of the effectiveness of streamer lines as a seabird by-catch mitigation technique in longline fisheries and CCAMLR streamer line requirements. CCAMLR Science, 11, 189201.
Ministry of Fisheries and Marine Resources (2013) Annual Report 2012–2013. Ministry of Fisheries and Marine Resources, Walvis Bay, Namibia.
Moreno, C.A., Arata, J.A., Rubilar, P., Hucke-Gaete, R. & Robertson, G. (2006) Artisanal longline fisheries in Southern Chile: lessons to be learned to avoid incidental seabird mortality. Biological Conservation, 127, 2736.
Petersen, S.L., Honig, M.B., Ryan, P.G., Underhill, L.G. & Goren, M. (2009) Seabird bycatch in the demersal longline fishery off southern Africa. African Journal of Marine Science, 31, 205214.
Plummer, M. (2015) JAGS Version 4.0.0 User Manual. Http://www.uvm.edu/~bbeckage/Teaching/DataAnalysis/Manuals/manual.jags.pdf [accessed 23 November 2016].
R Development Core Team (2013) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria.
Reid, T.A. & Sullivan, B.J. (2004) Longliners, black-browed albatross mortality and bait scavenging in Falkland Island waters: what is the relationship? Polar Biology, 27, 131139.
Reid, T.A., Sullivan, B.J., Pompert, J., Enticott, J.W. & Black, A.D. (2004) Seabird mortality associated with Patagonian toothfish (Dissostichus eleginoides) longliners in Falkland Islands waters. Emu, 104, 317325.
Robertson, G., Moreno, C.A., Gutiérrez, E., Candy, S.G., Melvin, E.F. & Seco Pon, J.P. (2008) Line weights of constant mass (and sink rates) for Spanish-system Patagonian toothfish longline vessels. CCAMLR Science, 15, 93106.
Rollinson, D.P., Dilley, B.J. & Ryan, P.G. (2014) Diving behaviour of white-chinned petrels and its relevance for mitigating longline bycatch. Polar Biology, 37, 13011308.
Seco Pon, J.P., Gandini, P.A. & Favero, M. (2007) Effect of longline configuration on seabird mortality in the Argentine semi-pelagic Kingclip Genypterus blacodes fishery. Fisheries Research, 85, 101105.
Shotwell, M. (2013) Applied nonparametric bootstrap with hierarchical and correlated data. Http://biostat.mc.vanderbilt.edu/wiki/Main/HowToBootstrapCorrelatedData [accessed 26 October 2013].
Venables, W.N. & Ripley, B.D. (2002) Modern Applied Statistics with S. 4th edition. Springer, New York, USA.
Weimerskirch, H., Brothers, N. & Jouventin, P. (1997) Population dynamics of wandering albatross Diomedea exulans and Amsterdam albatross D. amsterdamensis in the Indian Ocean and their relationships with longline fisheries: conservation implications. Biological Conservation, 79, 257270.
Weimerskirch, H., Catard, A., Prince, P.A., Cherel, Y. & Croxall, J.P. (1999) Foraging white-chinned petrels Procellaria aequinoctialis at risk: from the tropics to Antarctica. Biological Conservation, 87, 273275.
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Oryx
  • ISSN: 0030-6053
  • EISSN: 1365-3008
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