scholarly journals Estimates of the Abundance of Cetaceans in the Central North Atlantic from the T-NASS Icelandic and Faroese Ship Surveys Conducted in 2007

2020 ◽  
Vol 11 ◽  
Author(s):  
Daniel G. Pike ◽  
Thorvaldur Gunnlaugsson ◽  
Bjarni Mikkelsen ◽  
Sverrir Daniel Halldórsson ◽  
Gísli Víkingsson ◽  
...  
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Barents Sea ◽  
Humpback Whales ◽  
Physeter Macrocephalus ◽  
Survey Area ◽  
Distance Measurements ◽  
The Core ◽  
Abundance Estimates ◽  
Core Survey

The Trans-North Atlantic Sightings Survey (T-NASS) carried out in June-July 2007 was the fifth in a series of large-scale cetacean surveys conducted previously in 1987, 1989, 1995 and 2001. The core survey area covered an area of about 1.8 million nm² spanning from the Eastern Barents Sea at 34°E to the east coast of Canada, and between 52°N and 78°N in the east and south to 42°N in the west. We present design-based abundance estimates from the Faroese and Icelandic vessel survey components of T-NASS, as well as results from ancillary vessels which covered adjoining areas. The 4 dedicated survey vessels used a Buckland-Turnock (B-T) mode with a tracker platform searching an area ahead of the primary platform and tracking sightings to provide data for bias correction. Both uncorrected estimates, using the combined non-duplicate sightings from both platforms, and mark-recapture estimates, correcting estimates from the primary platform for bias due to perception and availability, are presented for those species with a sufficient number of sightings. Corrected estimates for the core survey area are as follows: fin whales (Balaenoptera physalus): 30,777 (CV=0.19); humpback whales (Megaptera novaeangliae): 18,105 (CV=0.43); sperm whales (Physeter macrocephalus): 12,268 (CV=0.33);  long-finned pilot whales (Globicephala melas): 87,417 (CV=0.38); white-beaked dolphins (Lagenorhynchus albirostris): 91,277 (CV=0.53); and white-sided dolphins (L. acutus): 81,008 (CV=0.54). Uncorrected estimates only were possible for common minke whales (B. acutorstrata): 12,427 (CV=0.27); and sei whales (B. borealis): 5,159 (CV=0.47). Sighting rates from the ancillary vessels, which used a single platform, were lower than those from the dedicated vessels in areas where they overlapped. No evidence of responsive movement by any species was detected, but there was some indication that distance measurements by the primary platform may have been negatively biased. The significance of this for the abundance estimates is discussed. The relative merits of B-T over other survey modes are discussed and recommendations for future surveys are provided.

scholarly journals Estimated Abundances of Cetacean Species in the Northeast Atlantic from Norwegian Shipboard Surveys Conducted in 2014–2018

2020 ◽  
Vol 11 ◽  
Author(s):  
Deanna Leonard ◽  
Nils Øien
Keyword(s):  
Barents Sea ◽  
Humpback Whales ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Target Species ◽  
Independent Observer ◽  
Southern Boundary ◽  
Norwegian Sea ◽  
Northeast Atlantic ◽  
Fin Whales

A ship-based mosaic survey of Northeast Atlantic cetaceans was conducted over a 5-year period between 2014–2018. The area surveyed extends from the North Sea in the south (southern boundary at 53oN), to the ice edge of the Barents Sea and the Greenland Sea. Survey vessels were equipped with 2 independent observer platforms that detected whales in passing mode and applied tracking procedures for the target species, common minke whales (Balaenoptera acutorostrata acutorostrata). Here we present abundance estimates for all non-target species for which there were sufficient sightings. We estimate the abundance of fin whales (Balaenoptera physalus) to be 11,387 (CV=0.17, 95% CI: 8,072–16,063), of humpback whales (Megaptera novaeangliae) to be 10,708 (CV=0.38, 95% CI: 4,906–23,370), of sperm whales (Physeter macrocephalus) to be 5,704 (CV=0.26, 95% CI: 3,374–9,643), of killer whales (Orcinus orca) to be 15,056 (CV=0.29, 95% CI: 8,423–26,914), of harbour porpoises (Phocoena phocoena) to be 255,929 (CV=0.20, 95% CI: 172,742–379,175), dolphins of genus Lagenorhynchus to be 192,767 (CV=0.25, 95% CI: 114,033–325,863), and finally of northern bottlenose whales (Hyperoodon ampullatus) to be 7,800 (CV=0.28, 95% CI: 4,373–13,913). Additionally, our survey effort in the Norwegian Sea in 2015 contributed to the 6th North Atlantic Sightings Survey (NASS) and the survey was extended into the waters north and east of Iceland around Jan Mayen island. This NASS extension, along with our Norwegian Sea survey in 2015, was used to estimate the abundance of fin whales, humpback whales, and sperm whales. All estimates presented used mark-recapture distance sampling techniques and were thus corrected for perception bias. Our estimates do not account for additional variance due to distributional shifts between years or biases due to availability or responsive movement.

Errors in identification using natural markings: rates, sources, and effects on capture–recapture estimates of abundance

2001 ◽  
Vol 58 (9) ◽  
pp. 1861-1870 ◽  
Author(s):  
Peter T Stevick ◽  
Per J Palsbøll ◽  
Tim D Smith ◽  
Mark V Bravington ◽  
Philip S Hammond
Keyword(s):  
Error Rate ◽  
Large Scale ◽  
False Negative ◽  
Parametric Bootstrap ◽  
Humpback Whales ◽  
The North ◽  
Abundance Estimates ◽  
Capture Recapture ◽  
Quality Rating ◽  
Estimation Of Variance

The results of a double-marking experiment using natural markings and microsatellite genetic markers to identify humpback whales (Megaptera novaeangliae) confirm that natural markings are a reliable means of identifying individuals on a large scale. Of 1410 instances of double tagging, there were 414 resightings. No false positive and 14 false negative errors were identified. The rate of error increased with decreasing photographic quality; no errors were observed among photographs of the highest quality rating, whereas an error rate of 0.125 was identified in sightings for which only part of the area used for identification was visible. There was also a weaker relationship between error rate and the distinctiveness of markings, which may result from non-independence in coding for image quality and distinctiveness. A correction is developed for the Petersen two-sample abundance estimator to account for false negative errors in identification, and a parametric bootstrap procedure for estimation of variance is also developed. In application to abundance estimates from the North Atlantic, the correction reduces the bias in estimates made using poorer quality photographs to a negligible level while maintaining comparable precision.

Expanding the North American Breeding Bird Survey Analysis to Include Additional Species and Regions

2017 ◽  
Vol 8 (1) ◽  
pp. 154-172 ◽  
Author(s):  
John R. Sauer ◽  
Daniel K. Niven ◽  
Keith L. Pardieck ◽  
David J. Ziolkowski ◽  
William A. Link
Keyword(s):  
New Species ◽  
North American ◽  
Breeding Bird Survey ◽  
Survey Area ◽  
Breeding Bird ◽  
Additional Species ◽  
The Core ◽  
The North ◽  
Bird Survey ◽  
Core Survey

Abstract The North American Breeding Bird Survey (BBS) contains data for >700 bird species, but analyses often focus on a core group of ∼420 species. We analyzed data for 122 species of North American birds for which data exist in the North American Breeding Bird Survey (BBS) database but are not routinely analyzed on the BBS Summary and Analysis Website. Many of these species occur in the northern part of the continent, on routes that fall outside the core survey area presently analyzed in the United States and southern Canada. Other species not historically analyzed occur in the core survey area with very limited data but have large portions of their ranges in Mexico and south. A third group of species not historically analyzed included species thought to be poorly surveyed by the BBS, such as rare, coastal, or nocturnal species. For 56 species found primarily in regions north of the core survey area, we expanded the scope of the analysis, using data from 1993 to 2014 during which ≥3 survey routes had been sampled in 6 northern strata (Bird Conservation regions in Alaska, Yukon, and Newfoundland and Labrador) and fitting log-linear hierarchical models for an augmented BBS survey area that included both the new northern strata and the core survey area. We also applied this model to 168 species historically analyzed in the BBS that had data from these additional northern strata. For both groups of species we calculated survey-wide trends for the both core and augmented survey areas from 1993 to 2014; for species that did not occur in the newly defined strata, we computed trends from 1966 to 2014. We evaluated trend estimates in terms of established credibility criteria for BBS results, screening for imprecise trends, small samples, and low relative abundance. Inclusion of data from the northern strata permitted estimation of trend for 56 species not historically analyzed, but only 4 of these were reasonably monitored and an additional 13 were questionably monitored; 39 of these species were likely poorly monitored because of small numbers of samples or very imprecisely estimated trends. Only 4 of 66 “new” species found in the core survey area were reasonably monitored by the BBS; 20 were questionably monitored; and 42 were likely poorly monitored by the BBS because of inefficiency in precision, abundance, or sample size. The hierarchical analyses we present provide a means for reasonable inclusion of the additional species and strata in a common analysis with data from the core area, a critical step in the evolution of the BBS as a continent-scale survey. We recommend that results be presented both 1) from 1993 to the present using the expanded survey area, and 2) from 1966 to the present for the core survey area. Although most of the “new” species we analyzed were poorly monitored by the BBS during 1993–2014, continued expansion of the BBS will improve the quality of information in future analyses for these species and for the many other species presently monitored by the BBS.

scholarly journals Statistical Approaches to Paternity Analysis in Natural Populations and Applications to the North Atlantic Humpback Whale

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1673-1682 ◽  
Author(s):  
Rasmus Nielsen ◽  
David K Mattila ◽  
Philip J Clapham ◽  
Per J Palsbøll
Keyword(s):  
Reproductive Success ◽  
North Atlantic ◽  
Natural Populations ◽  
Genetic Data ◽  
Paternity Analysis ◽  
New Method ◽  
Humpback Whales ◽  
The North ◽  
Abundance Estimates ◽  
Sampling Fraction

Abstract We present a new method for paternity analysis in natural populations that is based on genotypic data that can take the sampling fraction of putative parents into account. The method allows paternity assignment to be performed in a decision theoretic framework. Simulations are performed to evaluate the utility and robustness of the method and to assess how many loci are necessary for reliable paternity inference. In addition we present a method for testing hypotheses regarding relative reproductive success of different ecologically or behaviorally defined groups as well as a new method for estimating the current population size of males from genotypic data. This method is an extension of the fractional paternity method to the case where only a proportion of all putative fathers have been sampled. It can also be applied to provide abundance estimates of the number of breeding males from genetic data. Throughout, the methods were applied to genotypic data collected from North Atlantic humpback whales (Megaptera novaeangliae) to test if the males that appear dominant during the mating season have a higher reproductive success than the subdominant males.

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.

scholarly journals Distribution and abundance of large whales in Norwegian and adjacent waters based on ship surveys 1995-2001

2009 ◽  
Vol 7 ◽  
pp. 31 ◽  
Author(s):  
Nils Øien
Keyword(s):  
Species Abundance ◽  
Humpback Whale ◽  
Humpback Whales ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Species Identity ◽  
Independent Observer ◽  
Abundance Estimates ◽  
Partial Area ◽  
Fin Whales

The abundances of large whale species are presented for the northeast Atlantic from near-complete survey coverage in 1995 and from multiple partial-area surveys during 1996-2001. These Norwegian shipboard surveys were generally conducted with 2 independent observer platforms, except for single-platform surveys during part of 1995. Tracking procedures implemented for minke whales – Balaenoptera acutorostrata (the target species) meant that the surveys had to be conducted in passing mode, and there were therefore only limited opportunities for closing on sightings to determine species identity and school size. Abundance estimates for large whale species (fin – Balaenoptera physalus, humpback – Megaptera novaeangliae and sperm whales – Physeter macrocephalus) were obtained by combining sightings from both platforms, and applying standard distance sampling techniques to the smeared and truncated perpendicular distances for each species. Abundance estimates for the 2 survey groupings (1995 and 1996-2001) summarised over comparable areas were: fin whales, 5,034 (cv 0.209) and 6,409 (cv 0.18); humpback whales, 1,059 (cv 0.248) and 1,450 (cv 0.29); and sperm whales, 4,319 (cv 0.199) and 6,207 (cv 0.22). The estimated cv’s are likely underestimates and specifically the combined partial-area survey cv’s do not include additional variance due to possible distributional shifts between years. Inclusion of a new survey stratum north of Iceland (block NVS) in the later set of surveys revealed a high additional abundance there of fin whales 3,960 (cv 0.538) and humpback whales 3,246 (cv 0.512). The high humpback whale estimate for this stratum confirms the Icelandic survey findings of a large humpback whale population summering in that area.

Pilot cetacean survey of the sub-Arctic North Atlantic utilizing a cruise-ship platform

2007 ◽  
Vol 87 (1) ◽  
pp. 321-325 ◽  
Author(s):  
Ross Compton ◽  
Aaron Banks ◽  
Lissa Goodwin ◽  
Sascha K. Hooker
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
North Atlantic Ocean ◽  
Distance Sampling ◽  
Weather Conditions ◽  
Humpback Whales ◽  
Cruise Ship ◽  
Balaenoptera Acutorostrata ◽  
Cetacean Species ◽  
Minke Whales

Using a large passenger cruise-ship (MV ‘Discovery’) as a platform, a cetacean survey was conducted between 1 August and 3 September 2005 across the northern North Atlantic Ocean and back, covering waters between the UK, Iceland, Greenland and Canada. The objective was to collect sightings data for all cetacean species encountered to begin to collate information for a large-scale sightings database. Two observers employed standard-distance sampling techniques and visual observations (naked eye) to scan for cetaceans during daylight hours and favourable weather conditions. Approximately 112 h were spent surveying over 23 d. A total of 13 cetacean species were encountered, with 173 separate sightings recorded, totalling over 2000 animals. The most commonly sighted species were minke whales (Balaenoptera acutorostrata: N=44), Atlantic white-sided dolphins (Lagenorhynchus acutus: N=34, with group sizes of up to 600), and humpback whales (Megaptera novaeangliae: N=31). The distribution of minke whales, Atlantic white-sided dolphins and fin whales was linked to underlying oceanographic variables. Overall patterns of distribution were consistent with our understanding of the summer distributions for the species encountered. The survey highlighted the cetacean diversity of the northern North Atlantic region. Repeat work using this methodology will allow an examination of species' distributions and estimation of their relative abundance.

scholarly journals Artisanal and Aboriginal Subsistence Whaling in Saint Vincent and the Grenadines (Eastern Caribbean): History, Catch Characteristics, and Needs for Research and Management

2021 ◽  
Vol 8 ◽  
Author(s):  
Russell Fielding ◽  
Jeremy J. Kiszka
Keyword(s):  
National Policy ◽  
Sperm Whale ◽  
Humpback Whales ◽  
Physeter Macrocephalus ◽  
Policy Regimes ◽  
Caribbean History ◽  
Abundance Estimates ◽  
Formal Policy ◽  
Eastern Caribbean ◽  
Pilot Whales

Whaling has been a contentious international environmental issue for decades and carries complex ecological and socioeconomic implications. In Saint Vincent and the Grenadines (SVG), a small archipelagic nation located in the Eastern Caribbean, present-day whaling traces its origin to local interaction with American-based whalers during the nineteenth and early twentieth centuries. When American whaling in the region ceased, local shore-based whaling arose to fill the niche and to exploit the remaining, though diminished, stocks of large whales, as well as stocks of small cetaceans that the American whalers had not targeted as heavily. After a period of expansion throughout the late nineteenth and early twentieth centuries, which saw shore-whaling operations established on at least 11 islands in the region, Eastern Caribbean whaling experienced a period of attrition, during which most local whaling operations ceased. Two operations, both based in SVG, continue regularly today. This paper reviews the past and present status of whaling activities in SVG from the literature and using recent data collected from 2007 to 2017 through logbook data, interview surveys, and ethnographic observations. Small cetacean captures have been documented since 1949, and at least 15 species of odontocetes have been captured (primarily delphinids). From 1949 to 2017, a total of 13,856 small cetacean captures has been recorded, including 5,896 short-finned pilot whales (Globicephala macrorhynchus), 109 killer whales (Orcinus orca), and 7,851 other small cetaceans. Small cetacean catch records are largely incomplete and total catch estimates could not be attempted. Reliable abundance estimates do not exist. Consistent records for the take of large whales are only available for the period 1986–2020, during which 45 humpback whales (Megaptera novaeangliae) and 2 Bryde’s whales (Balaenoptera edeni) were taken. Additionally, 8 sperm whale (Physeter macrocephalus) captures were reported from 1967 and 1974. We also review whaling practices, existing national policy on whaling, management techniques outside of formal policy regimes, research needs, and future management perspectives. Future monitoring and management of whaling activities in SVG are strongly needed to assess the sustainability of small cetacean exploitation.

Habitat use of humpback whales in Godthaabsfjord, West Greenland, with implications for commercial exploitation

2010 ◽  
Vol 90 (8) ◽  
pp. 1529-1538 ◽  
Author(s):  
Tenna Kragh Boye ◽  
Malene Simon ◽  
Peter Teglberg Madsen
Keyword(s):  
North Atlantic ◽  
Site Fidelity ◽  
Large Scale ◽  
Early Spring ◽  
Humpback Whales ◽  
Small Scale ◽  
Whale Watching ◽  
Commercial Exploitation ◽  
West Greenland ◽  
Breeding Grounds

North Atlantic humpback whales migrate from breeding grounds to high latitude feeding areas to where individuals display large scale site fidelity. In Godthaabsfjord (Greenland), humpback whales are present from early spring to late autumn. To test for small scale site fidelity and occurrence, identification-photographs were collected from May to September 2007 and 2008 and compared with an older catalogue. We found high small scale site fidelity where 40% of the whales present in 2007 were resighted in 2008. The average resight rate from 1992 to 2008 was 30.2%. Individuals did not remain in the fjord the entire season and the time spent in the fjord was highly variable amongst individuals varying between 7–60% of the time from May to September. Individual humpback whales in the presence and absence of boats were tracked with a land-based theodolite to test for effects of whale watching on whale behaviour. Whale watch vessels were shown to significantly increase whale swimming speed, to shorten long dives and diminish the ratio between surfacings and long dives. It is concluded that the same foraging whales use this fjord system year after year, calling for regulation of whale watching and for consideration when discussing reopening the whaling of humpback whales in West Greenland.

scholarly journals Spatial Pattern and Zonal Shift of the North Atlantic Oscillation. Part II: Numerical Experiments

2010 ◽  
Vol 67 (9) ◽  
pp. 2827-2853 ◽  
Author(s):  
Dehai Luo ◽  
Linhao Zhong ◽  
Rongcai Ren ◽  
Chunzai Wang
Keyword(s):  
Spatial Pattern ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Large Scale ◽  
Storm Track ◽  
Lower Latitude ◽  
Eddy Activity ◽  
The Core ◽  
The North ◽  
Nao Pattern

Abstract In this part, the spatial evolution of an initial dipole anomaly in a prescribed jet is at first investigated by numerically solving linear and nonlinear models without forcing in order to examine how the spatial pattern of a dipole anomaly depends on the meridional distribution of a specified jet. It is shown that in a linear experiment an initial symmetric dipole anomaly in the meridional direction can evolve into a northeast–southwest (NE–SW) or northwest–southeast (NW–SE) tilted dipole structure if the core of this jet is in higher latitudes (the north) or in lower latitudes (the south). This is in agreement with the result predicted by the linear Rossby wave theory in slowly varying media. The conclusion also holds for the nonlinear and unforced experiment. North Atlantic Oscillation (NAO) events are then reproduced in a fully nonlinear barotropic model with a wavemaker that mimics the Atlantic storm-track eddy activity. In the absence of topography the spatial tilting of the eddy-driven NAO pattern is found to be independent of the NAO phase. The eddy-driven NAO pattern for the positive (negative) phase can exhibit a NE–SW (NW–SE) tilting only when the core of a prescribed jet prior to the NAO is confined in the higher latitude (lower latitude) region. However, in the presence of the wavenumber-2 topography (two oceans and continents) in the Northern Hemisphere the spatial tilting of the eddy-driven NAO dipole anomaly can be dependent on the NAO phase. Even when the specified basic flow prior to the NAO is uniform, the eddy-driven positive (negative) NAO phase dipole anomaly can also show a NE–SW (NW–SE) tilting because the northward (southward) shift of the excited westerly jet can occur in the presence of topography. In addition, it is found that when the wavemaker is closer to the position of the initial NAO, the eddy-driven positive (negative) NAO phase pattern can display a whole eastward shift and a more distinct NE–SW (NW–SE) tilting. This thus explains why the first empirical orthogonal function of the NAO pattern observed during 1998–2007 exhibits a more pronounced NE–SW tilting than during 1978–97. It appears that the latitudinal shift of the jet, the large-scale topography, and the zonal position of the Atlantic storm-track eddy activity are three important factors for controlling the spatial tilting and zonal shift of eddy-driven NAO dipole anomalies.

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