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

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.

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Abundance estimates of Southern Hemisphere Breeding Stock ‘D’ humpback whales from aerial and land-based surveys off Shark Bay, Western Australia, 2008

J. Cetacean Res. Manage. ◽

10.47536/jcrm.vi3.326 ◽

2020 ◽

pp. 209-221

Author(s):

Sharon L. Hedley ◽

John L. Bannister ◽

Rebecca A. Dunlop

Keyword(s):

Southern Hemisphere ◽

Western Australia ◽

Aerial Survey ◽

Humpback Whales ◽

Line Transect ◽

Breeding Stock ◽

Abundance Estimate ◽

Shark Bay ◽

Abundance Estimates ◽

Rate Of Increase

Single platform aerial line transect and land-based surveys of Southern Hemisphere Breeding Stock ‘D’ humpback whales Megaptera novaeangliaewere undertaken off Shark Bay, Western Australia to provide absolute abundance estimates of animals migrating northward along the westernAustralian coast. The aerial survey flew a total of 28 flights, of which 26 were completed successfully, from 24 June–19 August 2008. The landbased survey was undertaken from Cape Inscription, Dirk Hartog Island, Shark Bay, during the expected peak of the whales’ northward migration,from 8–20 July. During the first week of the land-based survey, some double count effort was undertaken to provide information on the numbersof pods missed from the land station. The assumed period of northward migration was 2 June–7 September. Estimated abundance of northwardmigrating whales during that time is 34,290 (95% CI: (27,340–53,350)), representing an annual rate of increase of 12.9% (CV = 0.20) since anestimate of 11,500 in 1999. This estimate is based on an estimate of relative abundance of surface-available whales of 10,840 (8,640–16,860), andan estimated g(0) of 0.32. There were considerable practical difficulties encountered during the land-based survey which reduced the effectivenessof the dual-survey approach for estimating g(0) for the aerial survey. Furthermore only about 15% of whales were estimated to be within the visualrange of the land-based station. Alternative approaches for estimating g(0) from these data are therefore also presented, resulting in considerablyhigher estimates of around 0.6–0.7, and yielding a conservative abundance estimate of 17,810 (14,210–27,720).

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Comparison of Helicopter Line Transects with Walked Line Transects for Estimating Densities of Kangaroos

Wildlife Research ◽

10.1071/wr96103 ◽

1997 ◽

Vol 24 (4) ◽

pp. 397 ◽

Cited By ~ 16

Author(s):

T. F. Clancy ◽

A. R. Pople ◽

L. A. Gibson

Keyword(s):

Repeated Measures ◽

Aerial Survey ◽

Survey Method ◽

Line Transect ◽

Attractive Alternative ◽

Line Transect Sampling ◽

Density Estimates ◽

Transect Sampling ◽

Grey Kangaroo ◽

Line Transects

The performance of helicopter surveys for estimating population densities of red kangaroos (Macropus rufus), eastern grey kangaroos (Macropus giganteus) and common wallaroos (Macropus robustus) was investigated by comparing line-transect density estimates obtained from helicopter surveys with those from ground (walked) surveys. Comparisons were made at four sites in central western Queensland (areas with high densities of red kangaroos and common wallaroos) that were surveyed during winter and summer from December 1991 until February 1995, and one site in south-eastern Queensland (an area of high eastern grey kangaroo density) surveyed annually during autumn from March 1991 until March 1994. Helicopter surveys generally recorded lower sample sizes than did ground surveys (means ± s.e = 34 ± 6%, 33 ± 9% and 76 ± 2% lower for red kangaroos, eastern grey kangaroos and wallaroos, respectively). Density estimates obtained from the helicopter surveys were not significantly different from those obtained from ground surveys for both red and eastern grey kangaroos as assessed by repeated-measures ANOVA and regression analysis. However, helicopter surveys of common wallaroos consistently returned density estimates about half those of ground surveys. The relationships between the two methods did not differ between winter and summer for any species. The conventional aerial survey method for kangaroos of strip transects from fixed-wing aircraft has limited ability to adjust for varying sightability conditions. Therefore, helicopter surveys with line-transect sampling are an attractive alternative.

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

NAMMCO Scientific Publications ◽

10.7557/3.4805 ◽

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.

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Comparison of Surveys of Kangaroos in Queensland Using Helicopters and Fixed-Wing Aircraft.

The Rangeland Journal ◽

10.1071/rj9980092 ◽

1998 ◽

Vol 20 (1) ◽

pp. 92 ◽

Cited By ~ 13

Author(s):

AR Pople ◽

SC Cairns ◽

TF Clancy ◽

GC Grigg ◽

LA Beard ◽

...

Keyword(s):

Aerial Survey ◽

Population Estimates ◽

Line Transect ◽

Correction Factors ◽

Density Estimates ◽

Australian State ◽

Transect Counts ◽

Comparative Accuracy ◽

Harvest Quotas ◽

Strip Transect

Kangaroo harvest quotas for each Australian state have been set mainly as proportions of population estimates derived from aerial surveys. Estimating population size from strip transect counts using fixed- wing aircraft has become an established technique, but counts must be adjusted by correction factors to ensure population estimates are both accurate and repeatable. Surveys of kangaroos in Queensland are currently conducted with helicopters using line transect methodology, but cost restricts their use to relatively small survey blocks. Nevertheless, they return more accurate and repeatable estimates of kangaroo density than surveys with fixed-wing aircraft. A comparison of the above two techniques was made along the same transect lines in seven survey blocks (5000-10,000 km2) in southern and western Queensland, allowing an assessment of the comparative accuracy of the fixed-wing method. For red kangaroos (Macropus rufus), required correction factors of 0.7-3.1 were similar to those used previously. However, for eastern grey kangaroos (M. giganteus), substantially larger correction factors of 3.4-10.2 were needed to approach true density. For wallaroos (M. robustus), correction factors of 3.8-4.8 were required, but can be considered conservative because helicopter-derived density estimates are known to be underestimated by a factor of 2-3. Further work is needed to establish how correction factors for each species should be applied on a broader scale and whether they lead to repeatable estimates of kangaroo density. Key words: aerial survey, line transect, correction factors, strip transect, wallaroo.

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

NAMMCO Scientific Publications ◽

10.7557/3.2710 ◽

2009 ◽

Vol 7 ◽

pp. 117 ◽

Cited By ~ 13

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.

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Absolute and relative abundance estimates of Australian east coast humpback whales (Megaptera novaeangliae)

J. Cetacean Res. Manage. ◽

10.47536/jcrm.vi.318 ◽

2020 ◽

pp. 243-252

Author(s):

Michael J. Noad ◽

Rebecca A. Dunlop ◽

David Paton ◽

Douglas H. Cato

Keyword(s):

Data Analysis ◽

East Coast ◽

Humpback Whales ◽

Absolute Abundance ◽

Abundance Estimate ◽

Abundance Estimates ◽

Rate Of Increase ◽

Migratory Population ◽

Australian Coastline ◽

Near Extinction

The humpback whales that migrate along the east coast of Australia were hunted to near-extinction in the 1950s and early 1960s. Two independentseries of land-based surveys conducted over the last 25 years during the whales’ northward migration along the Australian coastline havedemonstrated a rapid increase in the size of the population. In 2004 we conducted a survey of the migratory population as a continuation of theseseries of surveys. Two methods of data analysis were used in line with the previous surveys, both for calculation of absolute and relative abundance.We consider the best estimates for 2004 to be 7,090±660 (95% CI) whales with an annual rate of increase of 10.6±0.5% (95% CI) for 1987–2004.The rate of increase agrees with those previously obtained for this population and demonstrates the continuation of a strong post-exploitationrecovery. While there are still some uncertainties concerning the absolute abundance estimate and structure of this population, the rate of annualincrease should be independent of these and highly robust.

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Detectability of penguins in aerial surveys over the pack-ice off Antarctica

Wildlife Research ◽

10.1071/wr07093 ◽

2008 ◽

Vol 35 (4) ◽

pp. 349 ◽

Cited By ~ 3

Author(s):

Colin Southwell ◽

Charles G. M. Paxton ◽

David L. Borchers

Keyword(s):

Aerial Survey ◽

Line Transect ◽

Mark Recapture ◽

Transect Line ◽

Aerial Surveys ◽

Abundance Estimates ◽

Transect Sampling ◽

Pack Ice ◽

Additional Costs ◽

Ice Floes

Knowledge of penguin abundance at regional and circumpolar scales across the Southern Ocean is important for the development of ecosystem models and to estimate prey consumption by penguins to assess potential competition with fisheries’ operations. One means of estimating penguin abundance is to undertake aerial surveys across the pack-ice surrounding Antarctica where penguins forage. However, it has long been recognised that aerial counts and resultant abundance estimates are likely to be negatively biased unless detectability is estimated and taken into account. Mark–recapture line-transect methods were used to estimate the detectability of penguin groups resting on ice floes during helicopter surveys over the pack-ice off Antarctica. Group size had the greatest effect of several measured covariates on detectability. Despite a concerted effort to meet the central assumption of conventional line-transect sampling (all objects on the transect line are detected), this was close to being achieved by single observers only in the case of the occasional very large group of >20 penguins. Emperor penguins were more detectable than Adélie penguins. Although observers undertook an extensive simulation training program before the survey, overall they improved in their ability to detect penguin groups throughout the survey. Mark–recapture line-transect methods can provide less biased estimation than conventional line-transect methods in aerial survey applications. This improvement comes with some costs, including the need for more demanding data-recording procedures and the need to use larger, more expensive aircraft. These additional costs will often be small compared with the basic cost, but the gain in terms of improved estimation may be substantial.

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Abundance estimates and trends for humpback whales (Megaptera novaeangliae) in Antarctic Areas IV and V based on JARPA sightings data

J. Cetacean Res. Manage. ◽

10.47536/jcrm.vi.301 ◽

2020 ◽

pp. 75-94

Author(s):

Koji Matsuoka ◽

Takashi Hakamada ◽

Hiroshi Kiwada ◽

Hiroto Murase ◽

Shigetoshi Nishiwaki

Keyword(s):

Selection Criterion ◽

Megaptera Novaeangliae ◽

Humpback Whales ◽

Base Case ◽

Line Transect ◽

Point Estimates ◽

Abundance Estimates ◽

Eastern Australia ◽

The Antarctic ◽

Additional Variance

Sighting survey data from the Japanese Whale Research Program under Special Permit in the Antarctic (JARPA) are analysed to obtain abundanceestimates for humpback whales (Megaptera novaeangliae) south of 60°S. The surveys were conducted during the 1989/90–2004/05 austral summerseasons (mainly in January and February); the survey areas alternated between Area IV (70°E–130°E) and Area V (130°E to 170°W) each year.Primary sighting effort totalled 293,811 n.miles over 6,188 days. Abundance estimates are obtained using standard line transect analysis methodsand the program DISTANCE. Estimated densities of humpback whales were highest east of the Kerguelen Plateau (80°E–120°E). Abundanceestimates for Area IV range from 2,747 (CV = 0.153) in 1993/94 to 31,134 (CV = 0.123) in 2001/02, while those for Area V range from 602 (CV= 0.343) in 1990/91 to 9,342 (CV = 0.337) in 2004/05. The estimates are similar to those obtained from the International Whaling Commission’sIDCR-SOWER surveys, which were conducted in Area IV (in 1978/79, 1988/89 and 1998/99) and in Area V (in 1980/81, 1991/92 and 2001/02–2003/04). Estimated annual rates of increase for Area IV (16.4%; 95% CI = 9.5–23.3%) and Area V (12.1%; 95% CI = 1.7–22.6%) are also similarto those obtained from the IDCR-SOWER surveys. The total abundance in Areas IV and V based on the most recent JARPA surveys (2003/04 and2004/05 combined) is 37,125 (95% CI = 21,349–64,558); the confidence interval incorporates estimated additional variance. Results of severalsensitivity tests are presented that suggest that estimates of abundance and trends are not appreciably affected by factors such as different approachesto deal with survey coverage (which in some cases was poor or included gaps). Changes in the order in which survey strata were covered andpotential effects are investigated using a nested GLM approach; a QAIC model selection criterion suggests a preference for not attempting to adjustfor such changes. Under various sensitivity approaches, the point estimates of increase rates are not greatly affected for Area IV. Although theydrop by typically a half for most approaches for Area V, they nevertheless remain within the confidence limits of the base case estimate of 12.1%per year (95% CI = 1.7–22.6%). The presented results thus suggest that the estimated abundance of humpback whales in Area IV has increasedrapidly. Although there is also an increase indicated for Area V, it is neither as rapid nor as precisely estimated. Taking these results together withthe similar rates of increase estimated from coastal surveys off western and eastern Australia for Breeding Stocks D and E respectively, and givendemographic limitations on the increase rates possible for closed populations of humpback whales, the hypothesis is advanced that whales fromBreeding Stock E may have shifted their feeding distribution westward as their numbers have increased, perhaps to take advantage of the higherdensities of krill to be found to the west.

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Performance of manned and unmanned aerial surveys to collect visual data and imagery for estimating arctic cetacean density and associated uncertainty

Journal of Unmanned Vehicle Systems ◽

10.1139/juvs-2018-0002 ◽

2018 ◽

Vol 6 (3) ◽

pp. 128-154 ◽

Cited By ~ 9

Author(s):

M.C. Ferguson ◽

R.P. Angliss ◽

A. Kennedy ◽

B. Lynch ◽

A. Willoughby ◽

...

Keyword(s):

Marine Mammal ◽

Aerial Survey ◽

Small Sample ◽

Unmanned Aircraft ◽

Bowhead Whale ◽

Line Transect ◽

Camera System ◽

Density Estimates ◽

Aerial Surveys ◽

The Cost

Manned aerial surveys have been used successfully for decades to collect data to infer cetacean distribution, density (number of whales/km2), and abundance. Unmanned aircraft systems (UAS) have potential to augment or replace some manned aerial surveys for cetaceans. We conducted a three-way comparison among visual observations made by marine mammal observers aboard a Turbo Commander aircraft; imagery autonomously collected by a Nikon D810 camera system mounted to a belly port on the Turbo Commander; and imagery collected by a similar camera system on a remotely controlled ScanEagle® UAS operated by the US Navy. Bowhead whale density estimates derived from the marine mammal observer data were higher than those from the Turbo Commander imagery; comparisons to the UAS imagery depended on survey sector and analytical method. Beluga density estimates derived from either dataset collected aboard the Turbo Commander were higher than estimates derived from the UAS imagery. Uncertainties in density estimates derived from the marine mammal observer data were lower than estimates derived from either imagery dataset due to the small sample sizes in the imagery. The visual line-transect aerial survey conducted by marine mammal observers aboard the Turbo Commander was 68.5% of the cost of the photo strip-transect survey aboard the same aircraft and 9.4% of the cost of the UAS survey.

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Line transect estimates of humpback whale abundance and distribution on their wintering grounds in the coastal waters of Gabon

J. Cetacean Res. Manage. ◽

10.47536/jcrm.vi3.324 ◽

2020 ◽

pp. 153-160 ◽

Cited By ~ 1

Author(s):

Samantha Strindberg ◽

Peter J. Ersts ◽

Tim Collins ◽

Guy-Philippe Sounguet ◽

Howard C. Rosenbaum

Keyword(s):

Coastal Waters ◽

Survey Design ◽

Distance Sampling ◽

Research Programme ◽

Humpback Whale ◽

Aerial Survey ◽

Hydrocarbon Exploration ◽

Humpback Whales ◽

Equatorial Guinea ◽

Line Transect

There have been few recent estimates of abundance for humpback whales (Megaptera novaeangliae) in the eastern South Atlantic Ocean. The firstdistance sampling survey of the coastal waters of Gabon was conducted in 2002. The difficult logistics of covering a large survey region withlimited time, effort and refuelling opportunities required a line transect survey design that carefully balanced the theoretical demands of distancesampling with these constraints. Inshore/offshore zigzag transects were conducted to a distance of up to approximately 50 n.miles from the coastof Gabon corresponding to the 1,000m depth contour, from the border with Equatorial Guinea to a point south of Mayumba, near the Congo borderrepresenting 1,488 n.miles of survey effort. Seventy-nine different groups of humpback whales were observed throughout the survey area comprisinga northern (Equatorial Guinea to Cap Lopez) and southern (Cap Lopez to Gamba) survey stratum. Relatively large numbers of whales wereencountered throughout the southern stratum; encounter rates and densities were considerably lower in the northern stratum. The initial abundanceestimate from a distance sampling analysis suggests that more than 1,200 humpback whales were present in Gabon’s coastal waters during thesurvey period. This estimate does not account for either availability or perception bias. In addition, this instantaneous snapshot of the number ofwhales occupying Gabon’s coastal waters is likely to correspond to only a portion of the population that uses these waters over time. However, theabundance estimate derived from the aerial survey are consistent with those based on photographic and genetic capture-recapture techniques. Acontinuing research programme in this area will help refine estimates of humpback whale abundance and using genetic and photographic data alsoestablish the relationships between this and other populations. This is important given the potential overlap of humpback whales in large numbersthroughout this region and the current extent and continued expansion of hydrocarbon exploration and extraction activities throughout the Gulf ofGuinea.

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