The white-chinned petrel is the most common avian bycatch species in the Southern Ocean (Weimerskirch et al 1999; Gilman 2006; Robertson et al 2006; Birdlife International 2013). The high bycatch rate is due to seabirds, such as petrels, being attracted to pelagic and demersal longlines by bait and offal discarded from vessels (Gilman 2006; Bugoni et al 2008) and the high incident of spatial and temporal overlap between petrel foraging grounds and areas of fishery activity (Delord et al 2010b). Several characteristics of white-chinned petrels make the species particularly susceptible to bycatch:delayed breeding, low fecundity, and utilization throughout the life cycle of highly productive areas also targeted by fisheries are all contributing factors (Hamer et al 2002). The species has been reported as bycatch year-round in different locales, meaning that no season or place is "safe" for these birds (Bugoni et al 2008). Additionally, bycatch is likely male-biased (Ryan & Boix-Hinzen 1999; Nel et al 2002), skewing population dynamics.
Near breeding territory in the Crozet and Kergulen Island in the southern Indian Ocean, up to 94% of bycaught seabirds from 1997-2004 were white-chinned petrels (Weimerskirch et al 2000; Delord et al 2005). At Possession Island in the Crozet archipelago, the number of breeding pairs has decreased by 37.1% from 1983-2004; bycatch is believed to have played an important role in this population decline (Barbraud et al 2008).
In terms of mitigation, determining areas of overlap between white-chinned petrel foraging and longline fisheries could be beneficial, as this would allow for the development of time-area closures to protect the birds during breeding season (Delord et al 2010a). Conservation measures such as bird-scaring lines, streamer lines, night-set lines, and line weighting appear to have reduced the level of bycatch of the species (Waugh et al 2008). In 2003, at leaset 15,000 white-chinned petrels were caught globally as bycatch, and in 2009, this number was down to 300 individuals (Delord et al 2005, 2010a). However, more data is needed to accurately assess the scale of white-chinned petrel bycatch, as estimates vary greatly. Other mitigation measures include the eco-labeling of seafood products, regulation of offal discharge, and fishery-specific regulations (Gilman 2006).
On a global scale, it is difficult to prevent bycatch of the white-chinned petrel due to its broad distribution, and its diving abilities and diet (Delord et al 2005, 2010a; Moreno et al 1996, 2006; Murray et al 1993; Nel et al 2002; Robertson et al 2006; Peterson et al 2007).
References
Barbraud, C, C Marteau, V Ridoux, K Delord & H Weimerskirch. 2008. Demographic response of a population of white-chinned petrels Procellaria aequinoctialis to climate and longline fishery bycatch. Journal of Applied Ecology 45(5): 1460-1467.
BirdLife International. 2013. Species factsheet: Procellaria aequinoctialis. Accessed 23 January 2013. www.birdlife.org
Bugoni, L, PL Mancini, DS Monteiro, L Nascimento & TS Neves. 2008. Seabird bycatch in the Brazilian pelagic longline fishery and a review of capture rates in southwestern Atlantic Ocean. Endangered Species Research 5: 137-147.
Delord, K, N Gasco, H Weimerskirch & C Barbraud. 2005. Seabird mortality in the Patagonian toothfish longline fishery around Crozet and Kerguelen Islands, 2001-2003. CCAMLR Science 12:53-80.
Delord, K, N Gasco, C Barbraud & H Weimerskirch. 2010a. Multivariate effects on seabird bycatch in the legal Patagonian toothfish longline fishery around Crozet and Kerguelen Islands. Polar Biology 33: 367-378.
Delord, K, C Cotte, C Peron, C Marteau, P Pruvost, N Gasco, G Duhamel, Y Cherel & H Weimerskirch. 2010b. At-sea distribution and diet of an endangered top predator: relationship between white-chinned petrels and commercial longline fisheries. Endangered Species Research 13: 1-16.
Gilman, E. 2006. Incidental capture of seabirds in pelagic longline fisheries of the tropical and subtropical Pacific Islands region and draft Pacific Islands regional plan of action for reducing the incidental catch of seabirds in pelagic longline fisheries. Pacific Islands Forum Fisheries Agency, Honiara, Solomon Islands. 39 pp.
Hamer, KC, EA Schreiber & J Burger. 2002. Breeding biology, life histories and life history-environmental interactions in seabirds. In: EA Schreiber & J Burger (eds), Biology of Marine Seabirds, Surrey Beatty & Sons, Chipping Norton, Australia. pp. 20-45.
Moreno, CA, PS Rubilar, E Marschoff & L Benzaquen. 1996. Factors affecting the incidental mortality of seabirds in the Dissostichus eleginoides in the southwest Atlantic (subarea 48.3, 1995 season). CCAMLR Science 3: 79-91.
Moreno, CA, J Arata, PS Rubilar, R Hucke-Gaete & GG Robertson. 2006. Artisanal longline fisheries in southern Chile: lessons to be learned to avoid incidental seabird mortality. Biological Conservation 127: 27-36.
Murray, TE, JA Bartle, SR Kalish & PR Taylor. 1993. Incidental capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992. Bird Conservation International 3: 181-210.
Nel, DC, PG Ryan & BP Watkins. 2002. Seabird mortality in the Patagonian toothfish longline fishery around the Prince Edward Islands, 1996-2000. Antarctic Science 14: 151-161.
Petersen, SL, MB Honig & D Nel, 2007. The impact of longline fisheries on seabirds in the Benguela Current Large Marine Ecosystem, In: S Petersen, D Nel & A Omardien (eds), Towards an ecosystem approach to longline fisheries in the Benguela: an assessment of impacts on seabirds, sea turtles and sharks. WWF South Africa Report Series 2007/Marine/001. WWF-SA, Die Boord, pp. 9-31.
Robertson, G, M McNeill, N Smith, B Wienecke, S Candy & F Olivier. 2006. Fast-sinking (integrated weight) longlines reduce mortality of white-chinned petrels (Procellaria aequinoctialis) and sooty shearwaters (Puffus griseus) in demersal longline fisheries. Biological Conservation 132: 459-471.
Ryan, PG & C Boix-Hinzen. 1999. Consistent male-biased seabird mortality in the Patagonian toothfish longline fishery. Auk 116: 851-854.
Waugh, SM, DI MacKenzie & D Fletcher. 2008. Seabird bycatch in New Zealand trawl and longline fisheries, 1998-2004. Papers and Proceedings of the Royal Society of Tasmania 142(1): 45-66.
Weimerskirch, H, A Catard, PA Prince, Y Cherel & JP Croxall, 1999. Foraging white-chinned petrels Procellaria aequinoctialis at risk: from the tropics to Antarctica. Biological Conservation 87: 273-275.
Weimerskirch, H. D Capdeville & G Duhamel. 2000. Factors affecting the number and mortality of seabirds attending trawlers and long-liners in the Kerguelen area. Polar Biology 23: 236-249.