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Full-Text Articles in Physical Sciences and Mathematics
Chilean Blue Whales As A Case Study To Illustrate Methods To Estimate Abundance And Evaluate Conservation Status Of Rare Species, Rob Williams, Sharon L. Hedley, Trevor A. Branch, Mark B. Bravington, Alexandre N. Zerbini, Ken P. Findlay
Chilean Blue Whales As A Case Study To Illustrate Methods To Estimate Abundance And Evaluate Conservation Status Of Rare Species, Rob Williams, Sharon L. Hedley, Trevor A. Branch, Mark B. Bravington, Alexandre N. Zerbini, Ken P. Findlay
United States Department of Commerce: Staff Publications
Often abundance of rare species cannot be estimated with conventional design-based methods, so we illustrate with a population of blue whales ( Balaenoptera musculus) a spatial model-based method to estimate abundance. We analyzed data from line-transect surveys of blue whales off the coast of Chile, where the population was hunted to low levels. Field protocols allowed deviation from planned track lines to collect identification photographs and tissue samples for genetic analyses, which resulted in an ad hoc sampling design with increased effort in areas of higher densities. Thus, we used spatial modeling methods to estimate abundance. Spatial models are increasingly …
Insights Into The Population Structure Of Blue Whales In The Eastern North Pacific From Recent Sightings And Photographic Identification, John Calambokidis, Jay Barlow, John K. B. Ford, Todd E. Chandler, Annie B. Douglas
Insights Into The Population Structure Of Blue Whales In The Eastern North Pacific From Recent Sightings And Photographic Identification, John Calambokidis, Jay Barlow, John K. B. Ford, Todd E. Chandler, Annie B. Douglas
United States Department of Commerce: Staff Publications
Blue whales were widely distributed in the North Pacific prior to the primary period of modern commercial whaling in the early 1900s. Despite concentrations of blue whale catches off British Columbia and in the Gulf of Alaska, there had been few documented sightings in these areas since whaling for blue whales ended in 1965. In contrast, large concentrations of blue whales have been documented off California and Baja California and in the eastern tropical Pacific since the 1970s, but it was not known if these animals were part of the same population that previously ranged into Alaskan waters. We document …
Blue Whale Visual And Acoustic Encounter Rates In The Southern California Bight, Erin M. Oleson, John Calambokidis, Jay Barlow, John A. Hildebrand
Blue Whale Visual And Acoustic Encounter Rates In The Southern California Bight, Erin M. Oleson, John Calambokidis, Jay Barlow, John A. Hildebrand
United States Department of Commerce: Staff Publications
The relationship between blue whale (Balaenoptera musculus) visual and acoustic encounter rates was quantitatively evaluated using hourly counts of detected whales during shipboard surveys off southern California. Encounter rates were estimated using temporal, geographic, and weather variables within a generalized additive model framework. Visual encounters (2.06 animals/h, CV = 0.10) varied with subregion, Julian day, time of day, and year. Acoustic encounters of whales producing pulsed A and tonal B call sequences (song; 0.65 animals/h, CV = 0.06) varied by Julian day, survey mode (transit or stationary), and subregion, and encounters of whales producing downswept (D) calls (0.41 …