Using Stable Isotopes to Assign Origin of White‐Chinned Petrels Killed by Longline Fisheries

Barquete, Viviane ORCID: https://orcid.org/0009-0006-2450-5312; Cherel, Yves ORCID: https://orcid.org/0000-0001-9469-9489; Phillips, Richard A. ORCID: https://orcid.org/0000-0002-0208-1444; Thompson, David; Chilvers, B. Louise ORCID: https://orcid.org/0000-0002-7657-4217; Wanless, Ross M.; Ryan, Peter G. ORCID: https://orcid.org/0000-0002-3356-2056. 2025 Using Stable Isotopes to Assign Origin of White‐Chinned Petrels Killed by Longline Fisheries. Aquatic Conservation: Marine and Freshwater Ecosystems, 35 (7), e70182. 10, pp. 10.1002/aqc.70182

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Text (Open Access) © 2025 The Author(s). Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd. Aquatic Conservation - 2025 - Barquete - Using Stable Isotopes to Assign Origin of White‐Chinned Petrels Killed by Longline.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (1MB) | Preview

Abstract/Summary

Incidental capture (bycatch) of seabirds in longline and trawl fisheries is one of the main threats to many albatrosses and large petrels. The White‐chinned Petrel ( Procellaria aequinoctialis ) has a circumpolar distribution and is the seabird species killed most frequently by fisheries in the Southern Ocean. In an attempt to identify provenance, stable isotope values ( δ 13 C and δ 15 N) in feathers from White‐chinned Petrels killed in longline fisheries off Brazil, South Africa and New Zealand were compared with those from petrels breeding at five major colonies (South Georgia, Prince Edward, Crozet, Kerguelen and Antipodes Islands). Feather δ 15 N, and to a lesser extent, δ 13 C values in feathers differed among breeding birds sampled at South Georgia, Antipodes Islands and the three Indian Ocean colonies. Given that adult feathers are moulted primarily in temperate waters, away from their colonies, this confirms that most adults from these three regions winter in different areas. Discriminant function analysis of stable isotope values indicated that most petrels killed off Brazil and South Africa were from Atlantic and Indian Ocean populations, respectively. Birds killed in New Zealand fisheries in summer were assigned to populations from all three oceans, with few assigned to the Antipodes; however, we lacked stable isotope data from the Auckland Islands, which is the most likely source population. Identifying the origin of bycaught birds is essential for determining which populations are affected by human activities and for prioritising conservation efforts. This includes targeting of mitigation regulations, monitoring of compliance and bycatch rates, and ensuring cooperation between breeding and non‐breeding range states to ensure best practices are adopted in national fisheries and in the high seas.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1002/aqc.70182
ISSN:	1052-7613
Additional Keywords:	bycatch, feathers, Procellaria aequinoctialis, provenance, stable isotopes
Date made live:	10 Jul 2025 09:53 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/539845

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