DOI: 10.5061/dryad.1zcrjdfts
title: Fisheries bycatch mitigation measures as an efficient tool for the conservation of seabird populations

description: The impact of industrial fisheries on marine biodiversity is conspicuous
 in large pelagic vertebrate fisheries bycatch. In seabirds, this led to
 the decline of many populations since the 1980s following the rise of
 global fishing efforts. Bycatch mitigation measures were implemented in
 the 2000s, but their effects on the concerned seabird populations remain
 poorly quantified and understood. We studied the effects of bycatch
 mitigation measures on the demography of the white-chinned petrel, one of
 the most bycatch impacted seabirds whose populations suffered dramatic
 declines before the implementation of mitigation measures. To do so we 1)
 built multi-event capture-recapture models to estimate the demographic
 parameters of a population from Possession Island (southern Indian Ocean)
 over thirty years, 2) assessed the effect of climate and fishery
 covariates on demographic parameters, 3) built a population matrix model
 to estimate stochastic growth rate according to the management in
 fisheries bycatch, and 4) estimated changes in breeding population density
 using distance sampling data. The population declined from the 1980s to
 the mid-2000s, while trawl and longline fisheries occurred with no bycatch
 mitigation measures. The negative effects of fishery bycatch through
 additive mortality and of rat predation on breeding success were likely
 the main drivers of this decline. Both modeled population growth rate and
 observed breeding densities showed an increase since the mid-2000s. We
 explained this trend by the improvement in survival probability following
 implementation of fishery bycatch mitigation measures and in breeding
 success probability with the local control of the rat population and
 changes in sea ice conditions on foraging grounds. Synthesis and
 applications: We provide a holistic approach to assess the effects of
 management measures by analysing datasets from sampling methods commonly
 employed in seabirds studies. Our conclusions should encourage the
 eradication of invasive predatory species in seabirds breeding areas and
 the strengthening of bycatch mitigation measures for the vulnerable
 seabird species, especially in international waters, but also the
 development of such measures considering the other marine large pelagic
 species threatened by fisheries bycatch (sharks, rays, turtles and marine
 mammals) since it could be crucial to avoid populations’ extinction.
description: <strong>Fisheries bycatch mitigation measures
 as an efficient tool for the conservation of seabird
 populations</strong> See
 supplementary: Fisheries bycatch mitigation measures as an efficient tool
 for the conservation of seabird populations. Here we
 also provide the capture-mark-recapture and distance sampling dataset we
 used for the study: Distance sampling data are
 formatted to be analysed with the software Distance (http://distancesampling.org/Distance) or with the R packages 'mrds' and 'Distance' (http://distancesampling.org/R). See the files "transects_WCP_Crozet_Pointe_Basse_2011-2012.txt" and "transects_WCP_Crozet_Pointe_Basse_2017-2018.txt". All distance measures are in metres. Capture-mark-recapture data are the life history of the white-chinned petrel from the 1986/1987 breeding season to the 2017/2018 breeding season. Those datasets are formatted to be analysed with the software E-SURGE (https://www.cefe.cnrs.fr/fr/recherche/bc/bbp/1045-desc/264-logiciel). See the files "CMR_WCP_adults_Crozet_Possession_1986-2017.inp" and "CMR_WCP_chicks_Crozet_Possession_1986-2017.inp".