White-chinned petrels are an abundant, widely distributed seabird species that breed in the sub-Antarctic and forage throughout the lower southern hemisphere (1,2). Petrels and many other seabirds produce small clutches, have a delayed maturity, high adult survival rates, and a long reproductive lifespan, and like most long-lived species are threatened by an increase in adult mortality (1 in 3,4,5) White-chinned petrels undertake some of the longest foraging trips of any seabird. During the breeding season , they travel up to 8,000 km at a time in search of krill and squid (6)
White chinned petrels are one of the most common bycatch species in demersal longline fisheries targeting hake, ling, and toothfish in the Southern Ocean (6,7,9). Petrels and other seabirds are attracted to baited longline hooks, and may be hooked or entangled and eventually drown as the gear is deployed. They also scavenge discards around trawl vessels, and may be trapped in nets or collide with warp cables and the gear itself (5). White-chinned petrels are particularly vulnerable to longlining because they are difficult to deter, forage both day and night, and can dive to 13 m to retrieve a baited longline hook, (9,10 in 7) while their extensive foraging journeys bring them into contact with at least 11 different longlining fleets (11). Longlining mortality has been implicated as a probable cause for the decline of major breeding colonies in South Georgia (2). Combined with predation and habitat loss, bycatch in longline fisheries likely will cause other populations to decline (8).
Integrated weight longlines, external weights, and underwater or side-setting devices help gear sink more quickly, minimizing the amount of time the longlining gear remains within diving range (3,7). Bird-scaring or “streamer” lines are an effective deterrent as well (3,7). Other bycatch mitigation strategies include implementing time/area closures and protected areas, setting gear at night, using blue-dyed bait to reduce visibility, and retaining fish processing waste onboard while fishing gear is in use (3,4). These measures are most effective when used in combination and implemented on a fishery-specific basis (3,12).
In the Southern Ocean, fisheries are managed under the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR), which was established in 1980 for the conservation and sustainable management of the Antarctic ecosystem (13). CCAMLR’s Commission represents the 25 member states and 9 acceding states which conduct research and/or harvesting activities in the Antarctic. Since 1989, CCAMLR has implemented conservation measures to reduce incidental seabird mortality within the Convention Area, including the use of weighted longlines and streamer lines, night-setting, and onboard waste retention (14). Although CCAMLR has reduced seabird mortality in the Convention Area by 99% since 1997 (15 in 3), this progress is threatened by the growth of illegal, unregulated and unreported (IUU) fisheries, as well as by fishing activity outside the Convention Area. (4,9)
References and additional resources:
1. Warham, J. 1990. The Petrels: Their Ecology and Breeding Systems. London: Academic Press
2. Berrow, S.D., J.P. Croxall and S.D. Grant. 2000. Status of white-chinned petrels Procellaria aequinoctialis Linneaus 1758 at Bird Island, South Georgia. Antarctic Science 12 (4): 399-405
3. Bull, L.S. 2007. Reducing seabird bycatch in longline, trawl and gillnet fisheries. Fish and Fisheries 8: 31-56
4. Weimerskirch, H., A. Catard, P.A. Prince, Y. Cherel, J.P. Croxall. 1999. Foraging white-chinned petrels Procellaria aequinoctialis at risk: From the tropics to Antarctica. Biological Conservation 87: 273-275
5. Gonzáles-Zevallos, D., and P. Yorio. 2006. Seabird use of discards and incidental captures at the Argentine hake trawl fishery in the Golfo San Jorge, Argentina. Marine Ecology Progress Series 316: 175-183
6. Berrow, S.D., A.G. Wood and P.A. Prince. 2000. Foraging location and range of White-Chinned Petrels Procellaria aequinoctialis breeding in the South Atlantic. Journal of Avian Biology 31: 303-311
7. Robertson, G., M. McNeill, N. Smith, B. Wienecke, S. Candy, and F. Olivier. 2006. Fast sinking (integrated weight) longlines reduce mortality of white-chinned petrels (Procellaria aequinoctialis) and sooty shearwaters (Puffinus griseus) in demersal longline fisheries. Biological Conservation 132: 458-471
8. BirdLife International 2005. Procellaria aequinoctialis. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. < >. Downloaded on 15 November 2007.
9. Kock, K. 2001. The direct influence of fishing and fishing-related activities on non-target species in the Southern Ocean with particular emphasis on longline fishing and its impact on albatrosses and petrels – a review. Reviews in Fish Biology and Fisheries 11: 31-56
10. Huin, N. 1994. Diving depths of white-chinned petrels. Condor 96: 1111-1113
11. Lewison, R.L., D.C. Nel, F. Taylor, J.P. Croxall and K.S. Rivera. 2005. Thinking big – taking a large-scale approach to seabird bycatch. Marine Ornithology 33: 1-5
12. Gilman, E., N. Brothers, and D.R. Kobayashi. 2005. Principles and approaches to abate seabird by-catch in longline fisheries. Fish and Fisheries 6: 35-49
13. Commission for the Conservation of Antarctic Marine Living Resources. General Introduction.
14. Commission for the Conservation of Antarctic Marine Living Resources. Conservation Measure 25-02 (2005): Minimisation of the incidental mortality of seabirds in the course of longline fishing or longline fishing research in the Convention Area.
15. Small, C.J. 2005. Regional Fisheries Management Organisations: Their Duties and Performance in Reducing Bycatch of Albatrosses and Other Species. Cambridge: BirdLife International