Which are the main threats affecting the marine megafauna in the Bay of Biscay?

García‐Barón, Isabel; Santos, M.B.; Uriarte, Adolfo; Inchausti, J. Ignacio; Escribano, J. Miguel; Albisu, Joxan; Fayos, Manena; Pis-Millán, J.A.; Oleaga, Álvaro; Mier, Francisco E. Alonso; Hernández, Orencio; Moreno, Obdulio; Louzao, Maité

doi:10.1016/j.csr.2019.07.009

Cited by 15 publications

(9 citation statements)

References 72 publications

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“…Our findings strengthen the knowledge of beaked whale spatial distribution within the Bay of Biscay, but also add an important temporal component by illustrating seasonal patterns in occurrence and the likelihood of year-round use of this region. Given the numerous anthropogenic threats faced by beaked whales (García-Barón et al, 2019) and the expanding presence of human activities within the Bay, future research focusing on addressing the paucity of winter survey effort in this area would be beneficial. It is crucial to understand not only where these animals occur, but also the relevance of temporal scales with regard to diurnal, seasonal, and long-term occupancy patterns to inform successful management decisions.…”

Section: Discussionmentioning

confidence: 99%

Likely year-round presence of beaked whales in the Bay of Biscay

et al. 2022

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Beaked whales are cryptic and difficult to study species, often distributed in deep offshore waters and only briefly visible at the surface. A diverse range of cetacean species has been documented in the Bay of Biscay, including several species of beaked whales. However, little is known about how persistent their presence is. Citizen science data collected during ferry-based surveys between 2006 and 2018 were analysed to investigate how encounter rates varied across space and time, and their drivers for beaked whale species. Approximately 244,400 km were surveyed, and there were 419 encounters with beaked whales recorded including Cuvier’s beaked whales, (n = 260), Northern bottlenose whales (n = 19), Sowerby’s beaked whales (n = 13), and True’s beaked whales (n = 1). Generalized Additive Models revealed that encounters were generally more frequent in the southern bay, on northern facing slopes, with all species except Sowerby’s showing a preference for both deep waters and shallow shelf waters. Animals were recorded in each of the eight surveyed months, suggesting that beaked whales may be present year-round, with increased encounter rates in summer months. This study is the first to indicate that beaked whales may persist in this area throughout the year, which is key information for appropriate management.

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Section: Discussionmentioning

confidence: 99%

Likely year-round presence of beaked whales in the Bay of Biscay

et al. 2022

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“…We identified as conservation features, that is, species of conservation interest, 10 seabird and three cetacean species whose populations are listed as protected under national and international legislation (see Table 1; García‐Barón et al., 2019). During the designation of the existing MPAs, not all of our conservation features were included as target species.…”

Section: Methodsmentioning

confidence: 99%

“…long-term monitoring, marine megafauna, marine protected areas, Marxan, systematic conservation planning, time series, Vessel Monitoring System MPAs, 10 of which belong to the Natura 2000 network and were designated under the EU Habitats Directive (92/43/EEC) and Birds Directive (79/409/EEC; Figure 1). The remaining MPA was designated as Protected Biotope under Spanish regional legislation (Decree 34/2009).We identified as conservation features, that is, species of conservation interest, 10 seabird and three cetacean species whose populations are listed as protected under national and international legislation (seeTable 1;García-Barón et al, 2019). During the designation of the existing MPAs, not all of our conservation features were included as target species.…”

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confidence: 99%

The value of time‐series data for conservation planning

García‐Barón

Giakoumi

Santos

et al. 2020

Journal of Applied Ecology

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Protected areas (PAs) are increasingly being used world‐wide for the conservation and management of wildlife. Systematic conservation planning (SCP) aims at ensuring biodiversity persistence while minimizing the threats faced by the species and/or the economic costs related to protection. To account for spatio‐temporal interactions between species and human threats, conservation planning for mobile wildlife requires time‐series data derived from monitoring of species and human threats, a process that is costly and technically challenging. Therefore, assessments of the monitoring period needed to ensure sufficient data input in the design of efficient, adequate and representative networks of PAs are crucial. We demonstrated the value of time‐series data in conservation planning by implementing SCP and data from different monitoring periods to identify priority conservation areas for highly mobile marine megafauna accounting for their main threat: commercial fishing. Two analyses of 10 reserve‐design scenarios each, replicated as many times as the data composing each scenario permitted were run in Marxan. The best solutions of the planning scenarios were statistically compared using the Cohen's Kappa test. We also assessed differences in spatial similarity among and within scenarios using the Wilcoxon nonparametric test and a non‐metric multidimensional scaling analysis. Finally, we compared the necessary cost and the area selected for each scenario. Our study highlights the importance of time‐series ecological and socioeconomic data for the robust selection of priority conservation areas. The results revealed different thresholds of the minimum temporal data required to design efficient networks of PAs for highly mobile species, demonstrating that the incorporation of data covering longer periods to the scenarios produce a more robust selection of priority conservation areas. Conservation plans using data covering <3 years were missing important priority areas. Synthesis and applications. We provide a method for estimating the minimum number of years of monitoring required to design efficient networks of protected areas that ensure the persistence of highly mobile species such as cetaceans and seabirds. This method can be used within an adaptive management framework to evaluate whether a network of protected areas performs as planned, and to test whether management strategies should be altered or adjusted in response to local and global changes.

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“…Anthropogenic activities and their cumulative impacts can take a heavy toll on populations. Common species may disappear, such as short-beaked common dolphins (Delphinus delphis, hereafter called common dolphins) in the Adriatic Sea (Bearzi and Reeves, 2021), or are under many threats, e.g., in the Bay of Biscay (García-Baron et al, 2019;Murphy et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Estimating Bycatch From Non-representative Samples (II): A Case Study of Pair Trawlers and Common Dolphins in the Bay of Biscay

et al. 2022

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Marine megafauna plays an important functional role in marine ecosystems as top predators but are threatened by a wide range of anthropogenic activities. Bycatch, the incidental capture of non-targeted species in commercial and recreational fisheries, is of particular concern for small cetacean species, such as dolphins and porpoises. In the North-East Atlantic, common dolphin (Delphinus delphis, Linné 1758) bycatch has been increasing and associated with large numbers of animals stranding during winter on the French Atlantic seashore since at least 2017. However, uncertainties around the true magnitude of common dolphin bycatch and the fisheries involved have led to delays in the implementation of mitigation measures. Current data collection on dolphin bycatch in France is with non-dedicated observers deployed on vessels for the purpose of national fisheries sampling programmes. These data cannot be assumed representative of the whole fisheries' bycatch events. This feature makes it difficult to use classic ratio estimators since they require a truly randomised sample of the fishery by dedicated observers. We applied a newly developed approach, regularised multilevel regression with post-stratification, to estimate total bycatch from unrepresentative samples and total fishing effort. The latter is needed for post-stratification and the former is analysed in a Bayesian framework with multilevel regression to regularise and better predict bycatch risk. We estimated the number of bycaught dolphins for each week and 10 International Council for the Exploration of the Sea (ICES) divisions from 2004 to 2020 by estimating jointly bycatch risk, haul duration, and the number of hauls per days at sea (DaS). Bycatch risk in pair trawlers flying the French flag was the highest in winter 2017 and 2019 and was associated with the longest haul durations. ICES divisions 8.a and 8.b (shelf part of the Bay of Biscay) were estimated to have the highest common dolphin bycatch. Our results were consistent with independent estimates of common dolphin bycatch from strandings. Our method show cases how non-representative observer data can nevertheless be analysed to estimate fishing duration, bycatch risk and, ultimately, the number of bycaught dolphins. These weekly-estimates improve upon current knowledge of the nature of common dolphin bycatch and can be used to inform management and policy decisions at a finer spatio-temporal scale than has been possible to date. Our results suggest that limiting haul duration, especially in winter, could serve as an effective mitigation strategy.

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Which are the main threats affecting the marine megafauna in the Bay of Biscay?

Cited by 15 publications

References 72 publications

Likely year-round presence of beaked whales in the Bay of Biscay

Likely year-round presence of beaked whales in the Bay of Biscay

The value of time‐series data for conservation planning

Estimating Bycatch From Non-representative Samples (II): A Case Study of Pair Trawlers and Common Dolphins in the Bay of Biscay

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