https://septentrio.uit.no/index.php/NAMMCOSP/issue/feed NAMMCO Scientific Publications 2019-09-16T15:02:46+02:00 Dr. Fern Wickson fern@nammco.no Open Journal Systems <p>The NAMMCO Scientific Publications series makes available in published, peer-reviewed form, scientific papers that have contributed to the work carried out by the NAMMCO Scientific Committee.</p> https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4689 Abundance of whales in West and East Greenland in summer 2015 2019-08-07T07:58:03+02:00 Rikke Guldborg Hansen rgh@ghsdk.dk Tenna K. Boye tebo@natur.gl Rasmus S. Larsen rslarsen@bio.ku.dk Nynne H. Nielsen nel@ghsdk.dk Outi Tervo outi@ghsdk.dk Rasmus D. Nielsen rdn@bios.au.dk Marianne H. Rasmussen mhr@hi.is Mikkel H. S. Sinding mhssinding@gmail.com Mads Peter Heide-Jørgensen mhj@ghsdk.dk <p>An aerial line transect survey of whales in West and East Greenland was conducted in August-September 2015. The survey covered the area between the coast of West Greenland and offshore (up to 100 km) to the shelf break. In East Greenland, the survey lines covered the area from the coast up to 50 km offshore crossing the shelf break. A total of 423 sightings of 12 cetacean species were obtained and abundance estimates were developed for common minke whale, (<em>Balaenoptera acutorostrata)</em> (32 sightings), fin whale (<em>Balaenoptera physalus</em>) (129 sightings), humpback whale (<em>Megaptera novaeangliae)</em> (84 sightings), harbour porpoise (<em>Phocoena phocoena)</em> (55 sightings), long-finned pilot whale, (<em>Globicephala melas)</em> (42 sightings) and white-beaked dolphin (<em>Lagenorhynchus albirostri)</em> (50 sightings). The developed at-surface abundance estimates were corrected for both perception bias and availability bias if possible. Data on surface corrections for minke whales and harbour porpoises were collected from whales instrumented with satellite-linked time-depth-recorders. Options for estimation methods are presented and the preferred estimates are: minke whales: 5,095 (95% CI: 2,171-11,961) in West Greenland and 2,762 (95% CI: 1,160-6,574) in East Greenland, fin whales: 2,215 (95% CI: 1,017-4,823) in West Greenland and 6,440 (95% CI: 3,901-10,632) in East Greenland, humpback whales: 993 (95% CI: 434-2,272) in West Greenland and 4,223 (95% CI: 1,845-9,666) in East Greenland, harbour porpoises: 83,321 (95% CI: 43,377-160,047) in West Greenland and 1,642 (95% CI: 319-8,464) in East Greenland, pilot whales: 9,190 (95% CI: 3,635-23,234) in West Greenland and 258 (95% CI: 50-1,354) in East Greenland, white-beaked dolphins 15,261 (95% CI: 7,048-33,046) in West Greenland and 11,889 (95% CI: 4,710-30,008) in East Greenland. The abundance of cetaceans in coastal areas of East Greenland has not been estimated before, but the limited historical information from the area indicates that the achieved abundance estimates were remarkably high. When comparing the abundance estimates from 2015 in West Greenland with a similar survey conducted in 2007, there is a clear trend towards lower densities in 2015 for the three baleen whale species and white-beaked dolphins. Harbour porpoises and pilot whales, however, did not show a similar decline. The decline in baleen whale and white-beaked dolphin abundance is likely due to emigration to the East Greenland shelf areas where recent climate driven changes in pelagic productivity may have accelerated favourable conditions for these species.</p> 2019-03-26T00:00:00+01:00 Copyright (c) 2019 Rikke Guldborg Hansen https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4643 Estimates of the relative abundance of long-finned pilot whales (Globicephala melas) in the Northeast Atlantic from 1987 to 2015 indicate no long-term trends 2019-08-02T15:58:20+02:00 Daniel G. Pike kinguq@gmail.com Thorvaldur Gunnlaugsson thorvaldur.gunnlaugsson@hafogvatn.is Geneviève Desportes genevieve@nammco.no Bjarni Mikkelsen bjarnim@savn.fo Gísli A. Vikingsson gisli.vikingsson@hafogvatn.is Dorete Bloch tjodsavnid@savn.fo <p>North Atlantic Sightings Surveys (NASS) and associated surveys, covering a large but variable portion of the North Atlantic, were conducted in 1987, 1989, 1995, 2001, 2007 and 2015. Previous estimates of long-finned pilot whale (<em>Globicephala melas</em>) abundance, derived using conventional distance sampling (CDS), are not directly comparable to one another because of differing survey coverage, field methods and, in the case of the 1989 NASS, different survey timing. CDS was used to develop indices of relative abundance to determine if pilot whale abundance has changed over the 28-year period from 1987 to 2015. The varying spatial coverage of the surveys is accommodated by delineating common regions that were covered by: i) all 6 surveys, and ii) the 3 largest surveys (1989, 1995, and 2007). These “Index Regions” were divided into East and West subregions, and post-stratification was used to obtain abundance estimates for these index areas only. Estimates are provided using the sightings from the combined platforms for surveys that used double platforms or the primary platform only.</p><p>Total abundance in the Index Regions, uncorrected for perception or availability biases, ranged from 54,264 (CV=0.48) in 2001 to 253,109 (CV=0.43) in 2015. There was no significant trend in the numbers of individuals or groups in either the 6 or 3 Survey Index Regions, and no consistent trend over the period. Power analyses indicate that negative annual growth rates of -3% to -5% would have been detectible over the entire period. The Index Regions comprise only a portion of the summer range of the species and changes in annual distribution clearly affect the results. Operational changes to the surveys, particularly in defining pilot whale groups, may also have introduced biases. Recommendations for future monitoring of the long-finned pilot whale population are provided.</p> 2019-02-12T00:00:00+01:00 Copyright (c) 2019 Daniel G. Pike, Thorvaldur Gunnlaugsson, Geneviève Desportes, Bjarni Mikkelsen, Gísli A. Vikingsson, Dorete Bloch https://septentrio.uit.no/index.php/NAMMCOSP/article/view/4941 Estimates of the abundance of cetaceans in the central North Atlantic based on the NASS Icelandic and Faroese shipboard surveys conducted in 2015 2019-09-16T15:02:46+02:00 Daniel G. Pike kinguq@gmail.com Thorvaldur Gunnlaugsson thorvaldur.gunnlaugsson@hafogvatn.is Bjarni Mikkelsen bjarnim@savn.fo Sverrir D. Halldórsson sverrir.daniel.halldorsson@hafogvatn.is Gísli Víkingsson gisli.vikingsson@hafogvatn.is <p>The North Atlantic Sightings Survey (NASS), the sixth in a series of surveys conducted between 1987 and 2015, was conducted in June/July 2015 and covered a large area of the northern North Atlantic. The Icelandic and Faroese ship survey component of the NASS covered the area between the Faroe Islands and East Greenland from latitude 52° to 72° N. The survey used 3 vessels and an independent double-platform configuration with each platform staffed by a minimum of 2 observers. Here we present both uncorrected abundance estimates derived using Multiple Covariates Distance Sampling, and corrected abundance estimates derived using Mark-Recapture Distance Sampling, for the following species: fin (<em>Balaenoptera physalus</em>), common minke (<em>B. acutorstrata</em>), humpback (<em>Megaptera novaeangliae</em>), blue (<em>B. musculus</em>), sei (<em>B. borealis</em>), sperm (<em>Physeter macrocephalus</em>), long-finned pilot (<em>Globicephala melas</em>) and northern bottlenose (<em>Hyperoodon ampullatus</em>) whales as well as white-beaked (<em>Lagenorhynchus albirostris</em>) and white-sided (<em>L. acutus</em>) dolphins. We then compare these estimates to those from previous NASS and put them into context with estimates from adjoining areas of the North Atlantic.</p> 2019-09-16T08:29:03+02:00 Copyright (c) 2019 Daniel Pike, Thorvaldur Gunnlaugsson, Bjarni Mikkelsen, Sverrir D. Halldórsson, Gísli Víkingsson