Seabird bycatch in Portuguese mainland coastal fisheries: An assessment through on-board observations and fishermen interviews

Oliveira, Nuno; Henriques, Ana Catarina; Miodonski, Joana; Pereira, Joana; Marujo, Débora; Almeida, Ana Margarida Pisco; Barros, Nuno; Andrade, Joana; Marçalo, Ana; Santos, J. Freitas; Oliveira, Isabel; Ferreira, Marisa; Araújo, Hélder; Monteiro, Sílvia S.; Vingada, José; Ramírez, Iván

doi:10.1016/j.gecco.2014.11.006

Cited by 50 publications

(29 citation statements)

References 24 publications

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“…Bycatch impacts from other gear, such as trawlers and purse‐seine vessels, have also been reported recently (Oliveira et al . ). Despite the fact that there is not a reliable estimate of the number of birds caught per year, there is no doubt that this figure is well above our estimated PBR value, and the rough estimated bycatch rate of about half of the mortality detected in Balearic shearwaters confirms that current fishery impact is unsustainable.…”

Section: Discussionmentioning

confidence: 97%

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

Genovart

Arcos²,

Álvarez

et al. 2016

Journal of Applied Ecology

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Summary 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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Section: Discussionmentioning

confidence: 97%

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

Genovart

Arcos²,

Álvarez

et al. 2016

Journal of Applied Ecology

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“…fishery, and area. Simulation results from a Portuguese study (Oliveira et al, 2015) indicated that estimated seabird bycatch and associated 95% confidence limit began to stabilize after around 80 interviews and 200 vessel-trips per stratum.…”

Section: Estimates Of Total Seabird Bycatchmentioning

confidence: 99%

“…To our knowledge, few studies have focused primarily on aspects related to sampling methods (but see Oliveira et al, 2015) and different estimators used for bycatch assessments. In this paper we aim to fill some of the knowledge gaps as presented above, exploring three identified fisheries outside Northern Norway; the coastal fishery for cod Gadhus morhua, the offshore fishery for Greenland halibut Reinhardtius hippoglossoides and the coastal fishery for lumpfish Cyclopterus lumpus.…”

Section: Introductionmentioning

confidence: 99%

Assessing incidental bycatch of seabirds in Norwegian coastal commercial fisheries: Empirical and methodological lessons

Fangel

Aas

Vølstad

et al. 2015

Global Ecology and Conservation

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a b s t r a c tWith diminishing seabird populations and little knowledge on incidental bycatch in fisheries in the Northeast Atlantic, this study aimed to screen seabird bycatch in Norwegian coastal fisheries in 2009. The purpose was to 1) quantify magnitude of seabird bycatch rates and estimate total bycatch from the entire fleet by different estimators 2) evaluate data from an access point survey against monitoring data from a reference fleet as methods for collecting data on bycatch mortality of seabirds and 3) give advice on further bycatch studies. The study focused on three small-vessel fisheries (<15 m LOA) outside Northern Norway; the coastal cod (gillnet and manual longline) and lumpfish (gillnet) fisheries and the more offshore Greenland halibut longline fishery. We found no correlation between landed catch and bycatch and upscaling was made based on number of fishing trips. In these fisheries, northern fulmars Fulmarus glacialis outnumbered the other species and constituted almost half of the overall bycatch, totalling about 5500 (mostly on longlines) of the >11 000 birds estimated caught. The black guillemot Cepphus gryllealso stood out as a numerous victim, constituting almost two thirds of the >3000 birds estimated to have drowned in lumpfish gillnets. The two methods were both considered to hold merit and yielded approximately similar estimates of the bycatch in the coastal cod fisheries, however BPUE differs. Further studies are recommended especially on the lumpfish gillnet and Greenland halibut longline fisheries and on temporal and spatial variations in bycatch. More studies are also needed to model effects on seabirds at the population level.

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“…Some evidence suggests that the majority of bycatch may occur during specific events, with dozens to hundreds of individuals killed, whereas many fishing line setting operations cause no bycatch (Laneri et al, 2010;Oliveira et al, 2015). For instance, up to 500…”

Section: Other Sources Of Variability In Bycatch Impactmentioning

confidence: 99%

Varying demographic impacts of different fisheries on three Mediterranean seabird species

Genovart

Doak

Igual

et al. 2017

Global Change Biology

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Fisheries have an enormous economic importance, but reconciling their socio-economic features with the conservation and sustainability of marine ecosystems presents major challenges. Bycatch mortality from fisheries is clearly among the most serious global threats for marine ecosystems, affecting a wide range of top predators. Recent estimates report ca. 200,000 seabirds killed annually by bycatch in European waters. However, there is an urgent need to rigorously estimate actual mortality rates and quantify effects of bycatch on populations. The Mediterranean Sea is one of the most impacted regions. Here, we estimate for the first time both bycatch mortality rates and their population-level effects on three endemic and vulnerable Mediterranean taxa: Scopoli's shearwater, Mediterranean shag, and Audouin's gull, that die in different types of fishing gears: longlines, gillnets and sport trolling, respectively. We use multi-event capture-recapture modelling to estimate crucial demographic parameters, including the probabilities of dying in different fishing gears. We then build stochastic demography models to forecast the viability of the populations under different management scenarios. Longline bycatch was particularly severe for adults of Scopoli's shearwaters and Audouin's gulls (ca. 28% and 23% of total mortality, respectively) and also for immature gulls (ca. 90% of mortality). Gillnets had a lower impact, but were still responsible for ca. 9% of juvenile mortality on shags, whereas sport trolling only slightly influenced total mortality in gulls. Bycatch mortality has high population-level impacts in all three species, with shearwaters having the highest extinction risk under current mortality rates. Different life-history traits and compensatory demographic mechanisms between the three species are probably influencing the different bycatch impact: for shearwaters, urgent conservation actions are required to ensure the viability of their populations. Results will be very useful for guiding future seabird conservation policies and moving towards an ecosystem-based approach to sustainable fisheries management.

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Seabird bycatch in Portuguese mainland coastal fisheries: An assessment through on-board observations and fishermen interviews

Cited by 50 publications

References 24 publications

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

Assessing incidental bycatch of seabirds in Norwegian coastal commercial fisheries: Empirical and methodological lessons

Varying demographic impacts of different fisheries on three Mediterranean seabird species

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