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Demography of the critically endangered Balearic shearwater: the impact of fisheries and time to extinction

Demography of the critically endangered Balearic shearwater: the impact of fisheries and time to extinction
Demography of the critically endangered Balearic shearwater: the impact of fisheries and time to extinction
World-wide, many seabirds are affected by fisheries in opposing ways: as a source of mortality from bycatch, but also by providing discards as a predictable and abundant food resource. This applies to the Balearic shearwater Puffinus mauretanicus, the most endangered European seabird, whose time to extinction was estimated at only ˜40 years a decade ago.

Since the previous assessment, new data and more sophisticated demographic modelling have become available, and new fishing policies from the European Union (Common Fisheries Policy, CFP) will apply, posing different scenarios for the viability of the species. Thus, there is both an urgent need and an opportunity for a more reliable update of the conservation status of the species.

Demographic data were collected between 1985 and 2014 at one of the world's largest colonies. Most demographic parameters were estimated using multievent capture–recapture modelling. Some parameters, such as bycatch rate, immature individual survival and recruitment, were estimated for the first time. We incorporated estimates into stochastic population models to forecast time to extinction and assess the viability under different management scenarios, accounting for upcoming fishing policies.

Adult survival was much lower than expected (0·809, SE: 0·013) and largely influenced by bycatch, which accounted for a minimum of 0·455 (SE: 0·230) of total mortality. Breeding success was positively correlated with discard availability. Recruitment started at low rates in 3-year-old birds (0·030, SE: 0·0455), increasing in following age classes and was almost complete at 6 years. Under the present scenario, we predict a time to extinction of 61 years (95% CI: 55–69).

Synthesis and applications. Population projections suggest that the actual impact of fisheries on Balearic shearwaters is unsustainable and the imminent discard ban under the new Common Fisheries Policy may accelerate the declining trend. This study demonstrates that reducing the bycatch rates of fisheries is an unavoidable and urgent conservation measure for avoiding the extinction of the species. We also advise setting up demographic long-term studies, to allow researchers to diagnose, with reliability, the effectiveness of management actions. These actions will also benefit many other marine top-predator species affected by this anthropogenic impact.
bycatch, conservation, discards, environmental policies, extinction, marine predator, multievent capture–recapture, population models, survival
1158-1168
Genovart, Meritxell
a77ebf2c-ac1c-4ea9-b5e7-75b50c0e56f1
Arcos, Jose Manuel
359b2ec3-71c0-44b2-9638-1bf4d1b1aba3
Álvarez, David
addf98de-d68b-4fa0-893e-75c3a12d9ee0
McMinn, Miguel
2e074f1f-1934-42a1-be35-67d42a3984f4
Meier, Rhiannon
987cfb29-5162-484d-b33c-3cb891cd9b68
Wynn, Russell
72ccd765-9240-45f8-9951-4552b497475a
Guilford, Tim
6f814dc8-b32a-4dab-9ff2-785e82395657
Oro, Daniel
c1dd94ad-dd08-4c84-ada0-f6eb280162c2
Genovart, Meritxell
a77ebf2c-ac1c-4ea9-b5e7-75b50c0e56f1
Arcos, Jose Manuel
359b2ec3-71c0-44b2-9638-1bf4d1b1aba3
Álvarez, David
addf98de-d68b-4fa0-893e-75c3a12d9ee0
McMinn, Miguel
2e074f1f-1934-42a1-be35-67d42a3984f4
Meier, Rhiannon
987cfb29-5162-484d-b33c-3cb891cd9b68
Wynn, Russell
72ccd765-9240-45f8-9951-4552b497475a
Guilford, Tim
6f814dc8-b32a-4dab-9ff2-785e82395657
Oro, Daniel
c1dd94ad-dd08-4c84-ada0-f6eb280162c2

Genovart, Meritxell, Arcos, Jose Manuel, Álvarez, David, McMinn, Miguel, Meier, Rhiannon, Wynn, Russell, Guilford, Tim and Oro, Daniel (2016) Demography of the critically endangered Balearic shearwater: the impact of fisheries and time to extinction. Journal of Applied Ecology, 53 (4), 1158-1168. (doi:10.1111/1365-2664.12622).

Record type: Article

Abstract

World-wide, many seabirds are affected by fisheries in opposing ways: as a source of mortality from bycatch, but also by providing discards as a predictable and abundant food resource. This applies to the Balearic shearwater Puffinus mauretanicus, the most endangered European seabird, whose time to extinction was estimated at only ˜40 years a decade ago.

Since the previous assessment, new data and more sophisticated demographic modelling have become available, and new fishing policies from the European Union (Common Fisheries Policy, CFP) will apply, posing different scenarios for the viability of the species. Thus, there is both an urgent need and an opportunity for a more reliable update of the conservation status of the species.

Demographic data were collected between 1985 and 2014 at one of the world's largest colonies. Most demographic parameters were estimated using multievent capture–recapture modelling. Some parameters, such as bycatch rate, immature individual survival and recruitment, were estimated for the first time. We incorporated estimates into stochastic population models to forecast time to extinction and assess the viability under different management scenarios, accounting for upcoming fishing policies.

Adult survival was much lower than expected (0·809, SE: 0·013) and largely influenced by bycatch, which accounted for a minimum of 0·455 (SE: 0·230) of total mortality. Breeding success was positively correlated with discard availability. Recruitment started at low rates in 3-year-old birds (0·030, SE: 0·0455), increasing in following age classes and was almost complete at 6 years. Under the present scenario, we predict a time to extinction of 61 years (95% CI: 55–69).

Synthesis and applications. Population projections suggest that the actual impact of fisheries on Balearic shearwaters is unsustainable and the imminent discard ban under the new Common Fisheries Policy may accelerate the declining trend. This study demonstrates that reducing the bycatch rates of fisheries is an unavoidable and urgent conservation measure for avoiding the extinction of the species. We also advise setting up demographic long-term studies, to allow researchers to diagnose, with reliability, the effectiveness of management actions. These actions will also benefit many other marine top-predator species affected by this anthropogenic impact.

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More information

Accepted/In Press date: 5 February 2016
e-pub ahead of print date: 8 March 2016
Published date: August 2016
Keywords: bycatch, conservation, discards, environmental policies, extinction, marine predator, multievent capture–recapture, population models, survival
Organisations: Geology & Geophysics, Marine Geoscience

Identifiers

Local EPrints ID: 389701
URI: http://eprints.soton.ac.uk/id/eprint/389701
PURE UUID: 2c93de62-afb4-43d3-94b3-034b868a2d52

Catalogue record

Date deposited: 11 Mar 2016 11:40
Last modified: 17 Dec 2019 06:54

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