scholarly journals Distribution and Abundance of Cetaceans in Icelandic Waters over 30 Years of Aerial Surveys

2020 ◽  
Vol 11 ◽  
Author(s):  
Daniel Pike ◽  
Thorvaldur Gunnlaugsson ◽  
Johann Sigurjonsson ◽  
Gisli Vikingsson
Keyword(s):  
Relative Abundance ◽  
Humpback Whales ◽  
Line Transect ◽  
Balaenoptera Acutorostrata ◽  
Aerial Surveys ◽  
Minke Whales ◽  
Abundance Estimates ◽  
Ecosystem Changes ◽  
Common Minke Whale ◽  
Icelandic Waters

Beginning in 1986, 7 aerial surveys covering the coastal waters of Iceland have been conducted up to 2016. In addition, several partial surveys covering portions of the same area and at different times of the year have been flown in the same 30 year time span. We present previously unpublished abundance estimates, corrected to the extent feasible for known biases, for common minke whales (Balaenoptera acutorostrata), humpback whales (Megaptera novaeangliae), white-beaked dolphins (Lagenorhynchus albirostris) and harbour porpoises (Phocoena phocoena) from some or all of the 2007, 2009 and 2016 surveys. The relative abundance of most species was comparatively low in the spring and fall, and peaked June and July when all of the main surveys have been carried out. An analysis of changes in line transect density as an index of relative abundance from all surveys indicates that common minke whale abundance decreased by 75% after 2001 and has remained at a relatively low level since then. Relative abundance of humpback whales and white-beaked dolphins has increased over the period 1986-2016. We place these observed changes in context with oceanographic and ecosystem changes documented over the same period.

scholarly journals Trends in the distribution and abundance of cetaceans from aerial surveys in Icelandic coastal waters, 1986-2001

2009 ◽  
Vol 7 ◽  
pp. 117 ◽  
Author(s):  
Daniel G Pike ◽  
Charles GM Paxton ◽  
Thorvaldur Gunnlaugsson ◽  
Gísli A Víkingsson
Keyword(s):  
Relative Abundance ◽  
Minke Whale ◽  
Humpback Whales ◽  
Line Transect ◽  
Survey Area ◽  
Balaenoptera Acutorostrata ◽  
The North ◽  
Aerial Surveys ◽  
Minke Whales ◽  
Abundance Estimates

Aerial surveys were carried out in coastal Icelandic waters 4 times between 1986 and 2001 as part of the North Atlantic Sightings Surveys. The surveys had nearly identical designs in 3 of the 4 years. The target species was the minke whale (Balaenoptera acutorostrata) but all species encountered were recorded. Sighting rate and density from line transect analysis were used as indices of relative abundance to monitor trends over the period, and abundance estimates corrected for perception biases were calculated for some species from the 2001 survey. More than 11 species were sighted, of which the most common were the minke whale, humpback whale (Megaptera novaeangliae), dolphins of genus Lagenorhychus, and the harbour porpoise (Phocoena phocoena). Minke whales anddolphins showed little change in distribution or abundance over the period. There were an estimated 31,653 (cv 0.30) dolphins in the survey area in 2001. Humpback whales increased rapidly at a rate of about 12%, with much of the increase occurring off eastern and northeastern Iceland. In 2001 there were an estimated 4,928 (cv 0.463) humpback whales in the survey area. The relative abundance of harbour porpoises decreased over the period, but estimates for this species were compromised by uncorrected perception biases and poor coverage. The ecological and historical significance of these findings with respect to previous whaling activities and present-day fisheries is discussed.

Marine megavertebrates of Cornwall and the Isles of Scilly: relative abundance and distribution

2011 ◽  
Vol 92 (8) ◽  
pp. 1823-1833 ◽  
Author(s):  
Ruth H. Leeney ◽  
Matthew J. Witt ◽  
Annette C. Broderick ◽  
John Buchanan ◽  
Daniel S. Jarvis ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Bottlenose Dolphins ◽  
Marine Biodiversity ◽  
Balaenoptera Acutorostrata ◽  
Delphinus Delphis ◽  
Mola Mola ◽  
Aerial Surveys ◽  
Minke Whales ◽  
Pilot Whales ◽  
Common Dolphins

We document patterns of distribution and relative abundance of marine megavertebrate fauna around Cornwall and the Isles of Scilly from a combination of aerial and boat-based surveying. Between January 2006 and November 2007, 20 aerial surveys were undertaken, comprising over 40 hours of on-effort flying time. In April to October of these years, 27 effort-corrected ferry surveys were also conducted from a passenger ferry travelling between Cornwall and the Isles of Scilly. Opportunistic sightings were also logged by the crew members of the ferry and another vessel travelling regularly along the same route on 155 days. Ten megavertebrate species were sighted: basking sharks Cetorhinus maximus, sunfish Mola mola, common dolphins Delphinus delphis, harbour porpoise Phocoena phocoena, grey seals Halichoerus grypus, Risso's dolphins Grampus griseus, bottlenose dolphins Tursiops truncatus, minke whales Balaenoptera acutorostrata, long-finned pilot whales Globicephala melas and killer whale Orcinus orca. During aerial surveys, 206 sighting events of seven species were made, compared with 145 sighting events of eight species during ferry surveys and 293 sighting events of 10 species from opportunistic ship-board data collection efforts. Seasonal and spatial patterns in species occurrence were evident. Basking sharks were the most commonly-sighted species in the region and were relatively abundant throughout the estimated 5 km-wide strip of coastal waters covered by the aerial surveys, during spring and summer. Ferry surveys and opportunistic vessel-based sightings data confirmed that the distribution of surface-feeding aggregations of this species was largely around the coasts. Despite the limited scope of this study, it has provided valuable baseline data, and possible insights into the marine biodiversity of the region.

Aerial surveys of cetaceans in the Gulf of St. Lawrence in 1995 and 1996

1998 ◽  
Vol 76 (8) ◽  
pp. 1529-1550 ◽  
Author(s):  
MCS Kingsley ◽  
R R Reeves
Keyword(s):  
Humpback Whales ◽  
Delphinapterus Leucas ◽  
Line Transect ◽  
Balaenoptera Acutorostrata ◽  
North Shore ◽  
The North ◽  
Minke Whales ◽  
Fin Whales ◽  
Pilot Whales ◽  
Blue Whales

Aerial line-transect surveys of cetaceans were flown in the Gulf of St. Lawrence in late August and early September of 1995 and in late July and early August of 1996. Systematic north-south transects were spaced 15prime of longitude apart. In 1995, the study area comprised the entire Gulf, divided into three strata for analysis; 69% was flown. In 1996, a single stratum covered only the north shore shelf; 75% of the design was flown. The survey platform was a light high-winged aircraft with bubble windows flown at 213 m (700 ft). Ten species were seen. Minke whales (Balaenoptera acutorostrata), Atlantic white-sided dolphins (Lagenorhynchus acutus), and harbour porpoises (Phocoena phocoena) yielded enough sightings to support good estimates, while fin whales (Balaenoptera physalus), humpback whales (Megaptera novaeangliae), white-beaked dolphins (Lagenorhynchus albirostris), and long-finned pilot whales (Globicephala melas) yielded few sightings and unreliable estimates. Blue whales (Balaenoptera musculus) and belugas (Delphinapterus leucas) were seen too rarely to support any analysis. The tenth species was a small delphinid, not positively identified. Minke whales were ubiquitous, but more common in the northern strata. We estimated about 1000 in the whole Gulf in 1995 and about 600 in the northernmost stratum in 1996 (these numbers, and those following, are uncorrected for visibility bias). We estimated about 12 000 Atlantic white-sided dolphins in the Gulf in 1995, but in 1996 saw hardly any, perhaps because we flew the survey earlier. Harbour porpoises (12 000 in 1995 and 21 000 in 1996) were most numerous in the northern stratum, but were also widely distributed at lower densities in the central and southern Gulf. White-beaked dolphins (2500 in 1995 and 2500 in 1996) occurred only in the Strait of Belle Isle and the extreme northeastern Gulf. We estimated a few hundred fin whales in the northern and central strata and about 100 humpbacks, mostly in the northeast. Long-finned pilot whales were only seen in the southeastern Gulf, surveyed only in 1995 (about 1500).

Recent changes in the diet composition of common minke whales(Balaenoptera acutorostrata)in Icelandic waters. A consequence of climate change?

2013 ◽  
Vol 10 (2) ◽  
pp. 138-152 ◽  
Author(s):  
Gísli A. Víkingsson ◽  
Bjarki Þór Elvarsson ◽  
Droplaug Ólafsdóttir ◽  
Jóhann Sigurjónsson ◽  
Valerie Chosson ◽  
...  
Keyword(s):  
Climate Change ◽  
Diet Composition ◽  
Balaenoptera Acutorostrata ◽  
Minke Whales ◽  
Icelandic Waters

scholarly journals Group IV humpback whales: their status from aerial and landbased surveys off Western Australia, 2005

2020 ◽  
pp. 223-234
Author(s):  
Charles G.M. Paxton ◽  
Sharon l. Hedley ◽  
John l. Bannister
Keyword(s):  
Aerial Survey ◽  
Group Iv ◽  
Humpback Whales ◽  
Reliable Estimate ◽  
Line Transect ◽  
Absolute Abundance ◽  
Density Estimates ◽  
Abundance Estimates ◽  
Short Period ◽  
Land Station

Single platform aerial line transect and land-based surveys of Southern Hemisphere Group IV humpback whales were undertaken to provide absoluteabundance estimates of animals migrating northward along the western Australian coast during June–August 2005. The aerial survey was designedto cover the whole period of northward migration but the resulting estimates from that survey alone could only, at best, provide relative abundanceestimates as it was not possible to estimate g(0), the detection probability along the trackline, from the data. Owing to logistical constraints, theland-based survey was only possible for a much shorter period (two weeks during the expected peak of the migration in mid-July). This paperproposes three methods that utilise these complementary data in different ways to attempt to obtain absolute abundance estimates. The aerial linetransect data were used to estimate relative whale density (for each day), allowing absolute abundance from the land-based survey to be estimatedfor the short period of its duration. In turn, the land-based survey allowed estimation of g(0) for the aerial survey. Absolute estimates of abundancefor the aerial survey were obtained by combining the g(0) estimate with the relative density estimates, summing over the appropriate number ofdays. The most reliable estimate of northward migrating whales passing the land station for the period of the land-based survey only was 4,700(95% CI 2,700–14,000). The most reliable estimate for the number of whales passing through the aerial survey region for the duration of that survey(55 days from June through to August) was 10,300 (95% CI 6,700–24,500). This is a conservative estimate because the duration of the aerial surveywas almost certainly shorter than the period of the migration. Extrapolation beyond the end of this survey was considered unreliable, but abundancefrom the estimated start of the migration to the end of the survey (87 days from mid-April to August) was estimated to be 12,800 (95% CI 7,500–44,600). The estimated number of whales depends crucially on the assumed migration and period of migration. Results for different migrationparameters are also presented. The point estimates of abundance, whilst higher than those from a previous survey in 1999 (when adjusted for surveyduration) are not significantly so. The peak of the whales’ distribution was found at c.90m water depth.

A note on minke whales (Cetacea: Balaenopteridae) in Uruguay: strandings review

2020 ◽  
Vol 21 (1) ◽  
pp. 135-140
Author(s):  
Eduardo Juri ◽  
Meica Valdivia ◽  
Paulo Cesar Simoes-Lopes ◽  
Alfredo Le Bas
Keyword(s):  
Atlantic Ocean ◽  
Minke Whale ◽  
Balaenoptera Acutorostrata ◽  
Southwest Atlantic ◽  
Antarctic Minke Whale ◽  
Minke Whales ◽  
Important Region ◽  
The Common ◽  
The Antarctic ◽  
Common Minke Whale

The minke whale is the smallest of the living rorquals and is widely distributed in the tropical, temperate and polar waters of both hemispheres. In the western Southwest Atlantic Ocean there are two currently recognised species, the dwarf form of the common minke whale, Balaenoptera acutorostrata unnamed subsp. and the Antarctic minke whale B. bonaerensis. All stranding records and collected specimens of minke whale on the coast of Uruguay were reviewed and analysed. Between 1962 and 2018, 33 records were gathered in a non-systematic way, 22 specimens of B. acutorostrata and 11 of B. bonaerensis. It was found that most animals were discovered alive or recently dead and assigned as neonates/young calves. This supports the hypothesis that Uruguayan coasts are part of an important region for reproduction and breeding for the species.

Net Entanglements of Baleen Whales in the Inshore Fishery of Newfoundland

1979 ◽  
Vol 36 (5) ◽  
pp. 521-528 ◽  
Author(s):  
J. S. Perkins ◽  
P. C. Beamish
Keyword(s):  
Key Words ◽  
Newfoundland And Labrador ◽  
Megaptera Novaeangliae ◽  
Humpback Whales ◽  
Balaenoptera Acutorostrata ◽  
Balaenoptera Physalus ◽  
Baleen Whales ◽  
Minke Whales ◽  
Capelin Mallotus Villosus ◽  
Inshore Waters

This paper documents net entrapments of baleen whales in the inshore waters of Newfoundland and Labrador. The species involved are principally minke whales (Balaenoptera acutorostrata) and humpback whales (Megaptera novaeangliae). Finback whales (Balaenoptera physalus) are also caught in nets but far less frequently. The timing of these entrapments corresponds with the spawning season for capelin (Mallotus villosus) on the beaches around the province. The magnitude and implications of this problem, both to the whales and the fisherman, are assessed. Key words: baleen whales, net entrapments, mortality assessment, capelin, Balaenoptera acutorostrata, B. physalus, Megaptera novaeangliae

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