Modelling common dolphin (Delphinus delphis) coastal distribution and habitat use: Insights for conservation

Paradell, Oriol Giralt; López, Bruno Díaz; Methion, Séverine

doi:10.1016/j.ocecoaman.2019.104836

Cited by 26 publications

(17 citation statements)

References 79 publications

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“…Common dolphin was the most frequently encountered species in this study, as well as the species with the biggest group size. It was also the most frequently sighted species in the EEZs of the Iberian Peninsula and Azores, where it has been often reported as the most abundant cetacean species (Correia et al., 2015; Giralt Paradell, Díaz López, & Methion, 2019; Moura et al., 2012, 2017; Silva et al., 2014). Although most commonly seen close to the coast in relatively shallow waters, common dolphins were also recorded offshore and in very deep waters.…”

Section: Discussionmentioning

confidence: 99%

Distribution of cetacean species at a large scale ‐ Connecting continents with the Macaronesian archipelagos in the eastern North Atlantic

Correia

Gil

Valente

et al. 2020

Diversity and Distributions

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Aim To describe distribution patterns and species richness of cetaceans along a wide geographical range using occurrence data coupled with survey effort, from poorly studied oceanic areas. Specific objectives were to compare species richness and relative abundances among sub‐regions and to describe the distribution of each species. Location Eastern North Atlantic. Time period 2012–2017. Major taxa studied Cetacea. Methods Cetacean monitoring was performed by dedicated observers from cargo ships, used as platforms of opportunity, along routes between Iberian Peninsula, Macaronesia and north‐western Africa. We mapped relative abundance (encounter rates), survey effort and species richness. We examined the dependence of the number of sightings and species richness on survey effort. The area was divided into sub‐regions (according to the Exclusive Economic Zones and international waters), and relative abundances of the eight most frequently sighted species, as well as species richness, were compared among them. In addition, we describe the distribution of each species in relation to sea depth, distance to coast, latitude and longitude. Results A total of 1,989 sightings were logged, and 26 cetacean species were identified. Species richness and relative abundances of the eight most common species differed substantially between sub‐regions. Common and bottlenose dolphins distributed in shallow coastal waters contrasting with the oceanic distribution of Stenella dolphins. Cuvier's beaked whale and minke whale had similar distributions. Pilot and sperm whales were distributed in southern waters. Main conclusions A considerable amount of survey effort was needed to attain reliable estimates of species richness. In less surveyed areas, species richness and abundance are likely to be underestimated. The offshore waters presented high species richness and several hotspots of cetacean abundance. This work provides new knowledge on cetacean distribution at a large scale in the eastern North Atlantic, relevant to future conservation management.

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Section: Discussionmentioning

confidence: 99%

Distribution of cetacean species at a large scale ‐ Connecting continents with the Macaronesian archipelagos in the eastern North Atlantic

Correia

Gil

Valente

et al. 2020

Diversity and Distributions

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“…Estimates of abundance in the order of millions have been reported for the Eastern Tropical Pacific (19.6 million km 2 ) in 2006 (3,127,203, CV = 0.26, density = 0.15 dolphins/km 2 ) (Gerrodette et al, 2008), and the California Current Ecosystem (1.14 million km 2 ) along the United States West Coast in 2014 (1,427,576, CV = 0.25, density = 1.25 dolphins/km 2 ) (Barlow, 2016), and tens of thousands for the United States Atlantic coast (463,000 km 2 ) in 2011 (N = 67,191, CV = 0.29, density = 0.14 dolphins/km 2 ) (Palka, 2012), European Atlantic shelf waters (1.37 million km 2 ) in 2005 (N = 56,221, CV = 0.23, density = 0.041 dolphins/km 2 ) (Hammond et al, 2013), and the southwestern Mediterranean sea (19,189 km 2 ) between 2000 and 2004 (N = 19,428, CV = 0.18, density = 1.01 dolphins/km 2 ) (Cañadas and Hammond, 2008). Across these areas, concentrations of common dolphins are often found in association with highly productive upwelling regions where prey is abundant (Ballance et al, 2006;Jefferson et al, 2009;Giralt Paradell et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Abundance and Potential Biological Removal of Common Dolphins Subject to Fishery Impacts in South Australian Waters

et al. 2021

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Conservation management of wildlife species should be underpinned by knowledge of their distribution and abundance, as well as impacts of human activities on their populations and habitats. Common dolphins (Delphinus delphis) are subject to incidental capture in a range of Australia’s commercial fisheries including gill netting, purse seining and mid-water trawling. The impact these fishery interactions have on common dolphin populations is uncertain, as estimates of abundance are lacking, particularly for the segments of the populations at risk of bycatch and in greater need of protection. Here we used double-observer platform aerial surveys and mark-recapture distance sampling methods to estimate the abundance of common dolphins in 2011 over an area of 42,438 km2 in central South Australia, where incidental mortality of common dolphins due to fisheries bycatch is the highest. We also used the potential biological removal (PBR) method to estimate sustainable levels of human-caused mortality for this segment of the population. The estimated abundance of common dolphins was 21,733 (CV = 0.25; 95% CI = 13,809–34,203) in austral summer/autumn and 26,504 in winter/spring (CV = 0.19; 95% CI = 19,488–36,046). Annual PBR estimates, assuming a conservative maximum population growth rate of Rmax = 0.02 and a recovery factor of Fr = 0.5 for species of unknown conservation status, ranged from 189 (summer/autumn) to 239 dolphins (winter/spring), and from 378 (summer/autumn) to 478 dolphins (winter/spring) with an Rmax = 0.04. Our results indicate that common dolphins are an abundant dolphin species in waters over the central South Australian continental shelf (up to 100 m deep). Based on the 2011 abundance estimates of this species, the highest estimated bycatch of common dolphins (423 mortalities in 2004/05) in the southern Australian region exceeded the precautionary PBR estimates for this population segment. Recent bycatch levels appear to be below PBR estimates, but low observer coverage and underreporting of dolphin mortalities by fishers means that estimates of dolphin bycatch rates are not robust. The effects of cumulative human impacts on common dolphins are not well understood, and thus we recommend a precautionary management approach to manage common dolphin bycatch based on local abundance estimates.

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“…Furthermore, S. frontalis and Balaenoptera edeni fall under the "special protection regime" (National Government: Royal Decree 139/2011, BOE N • 46, 23/02/2011; Regional Government: Decree 151/2001; BOC N • 097, 01/08/2001). The underlying scientific implication of these figures is the importance and relevance of these animals as key elements of ocean health and their role as major top-down regulators of marine ecosystem oceanic trophic chains (Reynolds et al, 2009;Giralt Paradell et al, 2019). Therefore, there is a clear need for further conservation efforts directed at the populations of these marine mammals in the Canary Islands.…”

Section: Discussionmentioning

confidence: 99%

Distribution of Cetaceans in the Canary Islands (Northeast Atlantic Ocean): Implications for the Natura 2000 Network and Future Conservation Measures

et al. 2021

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The waters of the Canary Islands are considered a hotspot for marine biodiversity, especially regarding cetacean species. Based on this fact, this study pays attention to the spatial distribution pattern of cetacean species and the conservation role of the Natura 2000 Network, a set of Special Areas of Conservation (SACs), which were defined mainly based on data compiled in 1996, under the framework of the European Habitats Directive. In recent years, the declaration of conservation areas for cetaceans between the Tenerife—La Gomera Islands by two global conservation programs, Mission Blue (“Hope Spots”) and Whale Heritage Site (“Whale Sanctuary”) sent clear signals of scientific and social interest to promote better protection of the cetacean species in the Canary Islands. The main aim of the designated SACs is the conservation of its biological and ecological diversity, ensuring the long-term survival of the target species in the waters around islands. In this case, the enactment of the SACs was based only on the sparse data available for the common bottlenose dolphin, Tursiops truncatus. This study shows that the spatial distribution of cetaceans in the Canary archipelago generated from a large database of cetacean sightings, from 2007 to 2018. The results obtained show the main marine areas where the different cetacean species are distributed around the different islands of the archipelago. The spatial distribution maps of the cetacean species, when compared with the existing SACs of the Natura 2000, show the need to extend these SACs into the open sea to include more cetacean species and a larger number of individuals for better conservation of the endangered marine mammals. As a consequence, some suggestions were proposed to improve and update the role of SACs in European Northeast Atlantic waters as a key environmental tool for cetacean conservation. The data supporting the recent declarations of these two new milestones the “Hope Spot” and the “Whale Sanctuary” enhance more keystone information to promote a large marine protected area in the Eastern Atlantic Ocean, such as the “Macaronesian Biodiversity and Ecological Migration Corridor for Cetaceans,” a conservation figure that has been already proposed in the scientific literature as a deserving candidate of governmental regulations and policies by Portugal and Spain; it would also require joint cross-border cooperation efforts for marine spatial planning.

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Modelling common dolphin (Delphinus delphis) coastal distribution and habitat use: Insights for conservation

Cited by 26 publications

References 79 publications

Distribution of cetacean species at a large scale ‐ Connecting continents with the Macaronesian archipelagos in the eastern North Atlantic

Distribution of cetacean species at a large scale ‐ Connecting continents with the Macaronesian archipelagos in the eastern North Atlantic

Abundance and Potential Biological Removal of Common Dolphins Subject to Fishery Impacts in South Australian Waters

Distribution of Cetaceans in the Canary Islands (Northeast Atlantic Ocean): Implications for the Natura 2000 Network and Future Conservation Measures

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