Trends in cetacean sightings along the Galician coast, north-west Spain, 2003–2007, and inferences about cetacean habitat preferences

2010 ◽  
Vol 90 (8) ◽  
pp. 1547-1560 ◽  
Author(s):  
Graham J. Pierce ◽  
Mara Caldas ◽  
Jose Cedeira ◽  
M. Begoña Santos ◽  
Ángela Llavona ◽  
...  
Keyword(s):  
Habitat Use ◽  
Continental Shelf ◽  
Bottlenose Dolphins ◽  
Habitat Preferences ◽  
Common Dolphin ◽  
Pilot Whale ◽  
Important Species ◽  
North West ◽  
Blue Whiting ◽  
Common Dolphins

Since mid-2003, systematic monthly sightings surveys for cetaceans have been carried out in Galicia (north-west Spain) from observation points around the coastline, with the aim of providing baseline data on cetacean distribution and habitat use to underpin future conservation measures. Here we summarize results for September 2003 to October 2007. The most frequently recorded species were the bottlenose dolphin (Tursiops truncatus, seen during 10.7% of observation periods), common dolphin (Delphinus delphis, 3.7%), harbour porpoise (Phocoena phocoena, 1.6%), Risso's dolphin (Grampus griseus, 0.4%) and short-finned pilot whale (Globicephala melas, 0.2%). The three most common species showed different distribution patterns along the coast. In terms of habitat preferences, bottlenose dolphins were seen to be associated with more productive areas (areas with higher chlorophyll-a concentrations) where the continental shelf was wider while both common dolphins and harbour porpoises were seen most frequently in less productive areas where the continental shelf is narrowest. Possible reasons for differences in habitat use include differing diets. In Galician waters, all three main cetacean species feed primarily on fish that are common in shelf waters, and in the case of blue whiting (the most important species in the stomach contents of common and bottlenose dolphins) abundant also on the slope. All three cetaceans feed on blue whiting while scad is important in diets of common dolphin and porpoise. It is also possible that porpoises do not use areas frequented by bottlenose dolphins in order to avoid aggressive interactions. Retrospective evaluation of the sampling regime, using data from the 2500 observation periods during 2003–2007 suggests that the overall sightings rates for all species (taking into account observation time and between-site travel time) would be higher if average observation duration was increased to at least 40 minutes. On the other hand, confidence limits on sightings rates stabilized after around 1000 observation periods, suggesting that the number of sites visited or the frequency of visits could be substantially reduced.

Temporal and spatial trends in stranding records of cetaceans on the Irish coast, 2002–2014

2016 ◽  
Vol 98 (5) ◽  
pp. 977-989 ◽  
Author(s):  
Barry McGovern ◽  
Ross M. Culloch ◽  
Michael O'Connell ◽  
Simon Berrow
Keyword(s):  
Bottlenose Dolphins ◽  
Linear Increase ◽  
Species Level ◽  
Common Dolphin ◽  
Sperm Whales ◽  
Pilot Whale ◽  
Management Guidelines ◽  
Significant Difference ◽  
Temporal And Spatial ◽  
Common Dolphins

Using Irish strandings data collected between 2002 and 2014, seasonal and annual trends in the number of strandings for all strandings identified to species level (N = 1480), and for the five most frequently reported species: common dolphin (25.7% of records), harbour porpoise (22.2%), long-finned pilot whale (8.8%), striped dolphin (6.9%) and bottlenose dolphin (6.9%) were investigated. With the exception of bottlenose dolphins, there was a significant linear increase in the number of strandings across years for all species and for all strandings collectively, that were identified to species-level. Only common dolphins demonstrated a significant increase in the proportion of records relative to all other strandings, which may be indicative of a real rise in the number of strandings of this species. Common dolphins and harbour porpoises showed a similar significant difference in monthly strandings, with more strandings occurring during the earlier months of the year. Significant differences in the gender of stranded animals were found in common, striped, bottlenose and Atlantic white-sided dolphins and sperm and pygmy sperm whales. Live and mass stranding events were primarily comprised of pelagic species. Most strandings occurred on the south and west coasts, with two hotspots for live and mass strandings identified. The patterns and trends identified are discussed in relation to the caveats in interpreting strandings data. Specifically to Ireland, the findings highlight the urgent need to build on the current volunteer reporting network and augment this comprehensive dataset with post-mortem examinations to better understand the cause of the trends identified. The importance of strandings data in informing conservation and management guidelines of these species’ is discussed.

Seasonal trends and spatial differences in marine mammal occurrence in Broadhaven Bay, north-west Ireland

2012 ◽  
Vol 92 (8) ◽  
pp. 1757-1766 ◽  
Author(s):  
Pia Anderwald ◽  
Michael Damien Haberlin ◽  
Mary Coleman ◽  
Oliver Ó Cadhla ◽  
Anneli Englund ◽  
...  
Keyword(s):  
Marine Mammal ◽  
Classification Tree ◽  
Bottlenose Dolphins ◽  
Additive Models ◽  
Harbour Porpoise ◽  
Habitats Directive ◽  
Common Dolphin ◽  
North West ◽  
Minke Whales ◽  
Common Dolphins

Long-term monitoring programmes of a comparatively small area complement larger scale, but temporally limited surveys and can provide extensive datasets on seasonal occurrence and fine-scale habitat use of multiple species. A marine mammal monitoring programme, involving year-round, land-based observations, has been conducted in Broadhaven Bay candidate Special Area of Conservation, north-west Ireland, during 2002, 2005 and 2008–2011. Nine cetacean and two seal species have been recorded, with grey seal, harbour porpoise, common and bottlenose dolphins, and minke whale present throughout the year. Generalized additive models, taking into account observer effort, sighting conditions (sea state) and interannual variation, did not reveal any significant seasonal patterns in the occurrence of grey seals, bottlenose dolphins and minke whales. On the other hand, common dolphin presence in Broadhaven Bay was highest during autumn and winter. Bottlenose dolphins could be separated spatially from both common dolphins and minke whales in a classification tree by their preferential use of the shallower inshore areas of the bay (<30 m depth). However, common dolphins and minke whales, which occurred mainly in the deeper outer section of Broadhaven Bay, could not be spatially distinguished from each other, and grey seals were distributed over the entire bay. Broadhaven Bay represents an important marine mammal habitat with respect to overall species diversity and the regular occurrence of bottlenose dolphin, harbour porpoise, grey and harbour seals (all listed under Annex II of the EU Habitats Directive).

scholarly journals Resource Occurrence and Productivity in Existing and Proposed Wind Energy Lease Areas on the Northeast US Shelf

2021 ◽  
Vol 8 ◽  
Author(s):  
Kevin D. Friedland ◽  
Elizabeth T. Methratta ◽  
Andrew B. Gill ◽  
Sarah K. Gaichas ◽  
Tobey H. Curtis ◽  
...  
Keyword(s):  
Habitat Use ◽  
Wind Energy ◽  
Continental Shelf ◽  
Marine Ecosystem ◽  
Atlantic Menhaden ◽  
Offshore Wind ◽  
Offshore Wind Energy ◽  
Important Species ◽  
Marine Habitats ◽  
Northeast Us

States in the Northeast United States have the ambitious goal of producing more than 22 GW of offshore wind energy in the coming decades. The infrastructure associated with offshore wind energy development is expected to modify marine habitats and potentially alter the ecosystem services. Species distribution models were constructed for a group of fish and macroinvertebrate taxa resident in the Northeast US Continental Shelf marine ecosystem. These models were analyzed to provide baseline context for impact assessment of lease areas in the Middle Atlantic Bight designated for renewable wind energy installations. Using random forest machine learning, models based on occurrence and biomass were constructed for 93 species providing seasonal depictions of their habitat distributions. We developed a scoring index to characterize lease area habitat use for each species. Subsequently, groups of species were identified that reflect varying levels of lease area habitat use ranging across high, moderate, low, and no reliance on the lease area habitats. Among the species with high to moderate reliance were black sea bass (Centropristis striata), summer flounder (Paralichthys dentatus), and Atlantic menhaden (Brevoortia tyrannus), which are important fisheries species in the region. Potential for impact was characterized by the number of species with habitat dependencies associated with lease areas and these varied with a number of continuous gradients. Habitats that support high biomass were distributed more to the northeast, while high occupancy habitats appeared to be further from the coast. There was no obvious effect of the size of the lease area on the importance of associated habitats. Model results indicated that physical drivers and lower trophic level indicators might strongly control the habitat distribution of ecologically and commercially important species in the wind lease areas. Therefore, physical and biological oceanography on the continental shelf proximate to wind energy infrastructure development should be monitored for changes in water column structure and the productivity of phytoplankton and zooplankton and the effects of these changes on the trophic system.

scholarly journals Trends in strandings and by-catch of marine mammals in north-west Spain during the 1990s

2002 ◽  
Vol 82 (3) ◽  
pp. 513-521 ◽  
Author(s):  
A. López ◽  
M.B. Santos ◽  
G.J. Pierce ◽  
A.F. González ◽  
X. Valeiras ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Atlantic Coast ◽  
Western Coast ◽  
Common Dolphin ◽  
North West ◽  
The North ◽  
By Catch ◽  
Average Size ◽  
Autumn And Winter ◽  
Common Dolphins

Strandings of marine mammals on the north-western Spanish coast (Galicia) have been systematically recorded since 1990. A total of 1433 marine mammals belonging to 15 species was recorded from 1990 to 1999. The most frequently recorded species stranded were common dolphin (47%), bottlenose dolphin (11%) and harbour porpoise (7%). The number of strandings recorded increased annually over the study period, probably reflecting an increased observer effort. During 1996–1999, an average of 1·65 animals were stranded annually for each 10 km of coastline, the highest density of strandings recorded on the Atlantic coast of the Iberian Peninsula. More than 80% of the strandings were located on the western coast of Galicia, mainly in autumn and winter. During the study period, 42 proven incidental catches were recorded, although signs of by-catch were seen in a further 198 animals. The average size of stranded common dolphins and the proportion of males both increased towards the end of the calendar year.

Stomach contents of English Channel cetaceans stranded on the coast of Normandy

2005 ◽  
Vol 85 (6) ◽  
pp. 1539-1546 ◽  
Author(s):  
J.F. De Pierrepont ◽  
B. Dubois ◽  
S. Desormonts ◽  
M.B. Santos ◽  
J.P. Robin
Keyword(s):  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Stomach Contents ◽  
Important Species ◽  
Stenella Coeruleoalba ◽  
Delphinus Delphis ◽  
Common Squid ◽  
Pilot Whales ◽  
The University ◽  
Common Dolphins

During 1998–2003 stomach contents of 47 marine mammals stranded on the coast of Normandy were analysed. The animals were first examined by a veterinary network and stomach contents were analysed at the University of Caen. The sample comprised: 26 common dolphins (Delphinus delphis), four bottlenose dolphins (Tursiops truncatus), seven harbour porpoises (Phocoena phoecoena), five grey seals (Halichoerus grypus), two long-finned pilot whales (Globicephala melas), one white beaked dolphin (Lagenorhynchus albirostris), one minke whale (Balaenoptera acurostrata) and one striped dolphin (Stenella coeruleoalba). The identification of food items was done using hard parts (i.e. fish otoliths and cephalopod beaks). Diet indices were computed including prey frequency and percentage by number. Common dolphins ate mainly gadoid fish (Trisopterus sp.), gobies and mackerel (Scomber scombrus). Cephalopods occurred in small numbers in the diet and commercially important species (cuttlefish and common squid) were scarce.

scholarly journals Habitat preferences among three top predators inhabiting a degraded ecosystem, the Black Sea

2017 ◽  
Vol 81 (2) ◽  
pp. 217 ◽  
Author(s):  
Alicia Sánchez-Cabanes ◽  
Maja Nimak-Wood ◽  
Nicola Harris ◽  
Renaud De Stephanis
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Black Sea ◽  
Bottlenose Dolphins ◽  
Habitat Preferences ◽  
Additive Models ◽  
Sea Surface ◽  
The Black Sea ◽  
Cetacean Species ◽  
Common Dolphins

This study investigated whether there is evidence of widespread niche partitioning based on environmental factors in the Black Sea and tested the hypothesis that physiographic factors may be employed as predictors. It addresses poorly researched areas with good habitat potential for the only three cetacean subspecies living in this area: the Black Sea short-beaked common dolphin (Delphinus delphis spp. ponticus), the Black Sea bottlenose dolphin (Tursiops truncatus spp. ponticus) and the Black Sea harbour porpoise (Phocoena phocoena spp. relicta). Generalized additive models (GAMs) were used to analyse data collected from multiple sources. In total, 745 sightings of the three species between 1998 and 2010 throughout the Black Sea were included. The analysis found depth and sea surface temperature to be the most important variables for separating the occurrence of the three species. Common dolphins occurred mainly in deep waters and in areas where the sea surface temperature was low, bottlenose dolphins were distributed primarily in shallower and warmer waters than common dolphins, and harbour porpoises were distributed in shallower waters with lower sea surface temperature than bottlenose dolphins. This study suggests strong niche segregation among the three cetacean species. The study is also the first contribution to the basic information of cetacean species distribution and habitat preferences in the Black Sea as a whole. Knowledge of the distribution of the three dolphin species in the study area is essential to establish conservation measures for these populations.

scholarly journals Distribution and habitat modelling of common dolphins (Delphinus delphis) in the eastern North Atlantic

2019 ◽  
Vol 99 (06) ◽  
pp. 1443-1457 ◽  
Author(s):  
Ana M. Correia ◽  
Ágatha Gil ◽  
Raul Valente ◽  
Massimiliano Rosso ◽  
Graham J. Pierce ◽  
...  
Keyword(s):  
North Atlantic ◽  
Chlorophyll Concentration ◽  
Temporal Distribution ◽  
Distribution Patterns ◽  
Encounter Rate ◽  
Common Dolphin ◽  
North West ◽  
Delphinus Delphis ◽  
Eastern North Atlantic ◽  
Common Dolphins

AbstractThe eastern North Atlantic (ENA) has many highly productive areas where several species of cetaceans have been recorded, with the common dolphin (Delphinus delphis) being one of the most frequently sighted species. However, its spatial and temporal distribution in high seas is poorly known. The study presents the results from 5 years of cetacean monitoring in the ENA (2012–2016) aboard cargo ships that follow the routes from Continental Portugal to the Macaronesian archipelagos and north-west Africa. Common dolphin was the most frequently sighted cetacean with 192 occurrences registered on effort and an overall encounter rate of 0.36 sightings/100 nmi. The species was distributed in coastal and offshore waters, but absent from the Canaries and Cape Verde islands. Statistical ‘habitat’ models were developed to describe and explain the occurrence of sightings of the species: variables affecting detection of dolphins had a small impact and there were clear spatiotemporal distribution patterns, influenced to some degree by environmental variables. Predicted probability of occurrence was highest in coastal waters of continental Portugal and around the Azores. The models, combined with maps of distribution, were useful to identify important areas for the species, which could be the focus of future conservation efforts. Common dolphin presence was related to depth, distance to coast and seamounts, seabed slope, chlorophyll concentration, sea-surface temperature and sea level anomalies; the possible ecological significance of these relationships is explored.

Summer distribution and relative abundance of cetacean populations off north-west Scotland

2003 ◽  
Vol 83 (5) ◽  
pp. 1187-1192 ◽  
Author(s):  
K. Macleod ◽  
M.P. Simmonds ◽  
E. Murray
Keyword(s):  
Relative Abundance ◽  
Sperm Whale ◽  
Abundant Species ◽  
Line Transect ◽  
Migration Route ◽  
Common Dolphin ◽  
Physeter Macrocephalus ◽  
Pilot Whale ◽  
North West ◽  
Line Transect Survey

A line transect survey was conducted in July/August 1998 to investigate the distribution and abundance of cetaceans off north-west Scotland. Over 2156.5 km of survey effort, 304 sightings were recorded of which 184 were identified to species. Nine species were identified: Atlantic white-sided dolphin Lagenorhynchus acutus, fin whale Balaenoptera physalus, sei whale Balaenoptera borealis, long-finned pilot whale Globicephala melas, sperm whale Physeter macrocephalus, common dolphin Delphinus delphis, harbour porpoise Phocoena phocoena, white beaked dolphin Lagenorhynchus albirostris and Risso's dolphin Grampus griseus. The Atlantic white-sided dolphin was the most relatively abundant species. The relative abundance of large whales and dolphins was greatest in the Faroe–Shetland Channel. The continental slopes of this area are undergoing development by oil industries and concerns have been raised about the potential impacts of these activities on cetaceans. These waters are used year-round by cetaceans and provide feeding and breeding grounds and are a migration route for large whales.

Habitat preferences and evidence for niche partitioning amongst cetaceans in the waters between Gabon and Angola, eastern tropical Atlantic

2012 ◽  
Vol 92 (8) ◽  
pp. 1735-1749 ◽  
Author(s):  
Caroline R. Weir ◽  
Colin D. MacLeod ◽  
Graham J. Pierce
Keyword(s):  
Water Depth ◽  
Habitat Preferences ◽  
Principal Component ◽  
Sperm Whale ◽  
Interspecific Variation ◽  
Common Dolphin ◽  
Tropical Atlantic ◽  
Cetacean Species ◽  
Pilot Whale ◽  
Species Pairs

The habitat preferences and niches of eight cetacean species inhabiting eastern tropical Atlantic waters between Angola and Gabon (1°N–11°S latitude) were examined. A total of 2873 cetacean sightings, recorded between January 2004 and June 2009, was assigned to 10 × 10 km grid cells and linked to four ecogeographical variables (EGVs): water depth, seabed slope, sea surface temperature (SST) and relative frontal strength. Classification trees revealed that the habitat preferences (in terms of the habitats sampled) of most species were primarily determined by SST (for Bryde's whale, sperm whale, short-finned pilot whale and common dolphin) and water depth (for Risso's dolphin, bottlenose dolphin and Atlantic spotted dolphin). Seabed slope was the most important EGV describing the presence of the striped dolphin. A principal component analysis was used to compare the niches of the species with respect to the four EGVs. Nineteen species pairs (68%) differed significantly in median principal component (PC) score for the first PC axis, suggesting differences in their niche centres for that axis. Sixteen species pairs (57%) differed significantly in PC score variance suggesting differences in the niche widths along the first PC axis. Water depth and SST were the most important variables for the first PC axis. Together, these results suggest that cetacean species inhabiting the eastern tropical Atlantic exhibit interspecific variation in their habitat preferences, and so differ in the niches that they occupy. These differences are most likely related to variation in prey species and foraging strategy.

Host specificity ofOschmarinella rochebruniandBrachycladium atlanticum(Digenea: Brachycladiidae) in five cetacean species from western Mediterranean waters

2010 ◽  
Vol 85 (1) ◽  
pp. 12-19 ◽  
Author(s):  
P. Mateu ◽  
J.A. Raga ◽  
F.J. Aznar
Keyword(s):  
Host Species ◽  
Bottlenose Dolphins ◽  
Western Mediterranean ◽  
Its2 Region ◽  
Single Individual ◽  
Common Dolphin ◽  
Cetacean Species ◽  
Stenella Coeruleoalba ◽  
Pilot Whales ◽  
Common Dolphins

AbstractWe investigated patterns of specificity of liver flukes (fam. Brachycladiidae) in a community of cetaceans from the western Mediterranean. The liver and pancreas of 103 striped dolphins,Stenella coeruleoalba, 18 Risso's dolphins,Grampus griseus, 14 bottlenose dolphins,Tursiops truncatus, 8 common dolphins,Delphinus delphis, and 5 long-finned pilot whales,Globicephala melas, were analysed for brachycladiid species. Two species were found:Oschmarinella rochebruniin striped dolphins (prevalence (P): 61.2%; mean intensity (MI) (95% CI): 34.2 (25.7–45.6)), andBrachycladium atlanticumin striped dolphins (P: 39.8%; MI: 7.1 (4.8–13.1)) and a single individual of common dolphin (P: 12.5%; intensity: 19), which represents a new host record. A molecular analysis using the internal transcribed spacer 2 (ITS2) region of the rDNA gene confirmed that specimens ofB. atlanticumwere conspecific regardless of host species. Available dietary data suggest that Risso's dolphins, bottlenose dolphins and long-finned pilot whales would contact rarely, if at all, the infective stages ofO. rochebruniandB. atlanticum. Neither the prevalence nor the mean abundance ofB. atlanticumdiffered significantly between striped and common dolphins, but a principal component analysis using seven morphometric variables indicated that specimens collected from the common dolphin were stunted. These worms also had fewer eggs compared with specimens typically found in striped dolphins, although the size of the eggs was similar in both host species. Dwarfism and low fecundity have typically been found in helminths infecting unusual host species, and might reflect the lower compatibility ofB. atlanticumfor common dolphins. In summary, bothO. rochebruniandB. atlanticumappear to exhibit a narrow specificity for striped dolphins in the western Mediterranean.

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