Foraging energetics and prey density requirements of western North Atlantic blue whales in the Estuary and Gulf of St. Lawrence, Canada

Terrestrial predators can modulate the energy used for prey capture to maximize efficiency, but diving animals face the conflicting metabolic demands of energy intake and the minimization of oxygen depletion during a breath hold. It is thought that diving predators optimize their foraging success when oxygen use and energy gain act as competing currencies, but this hypothesis has not been rigorously tested because it has been difficult to measure the quality of prey that is targeted by free-ranging animals. We used high-resolution multisensor digital tags attached to foraging blue whales (Balaenoptera musculus) with concurrent acoustic prey measurements to quantify foraging performance across depth and prey density gradients. We parameterized two competing physiological models to estimate energy gain and expenditure based on foraging decisions. Our analyses show that at low prey densities, blue whale feeding rates and energy intake were low to minimize oxygen use, but at higher prey densities feeding frequency increased to maximize energy intake. Contrary to previous paradigms, we demonstrate that blue whales are not indiscriminate grazers but instead switch foraging strategies in response to variation in prey density and depth to maximize energetic efficiency.

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Repeated Vessel Interactions and Climate- or Fishery-Driven Changes in Prey Density Limit Energy Acquisition by Foraging Blue Whales

Frontiers in Marine Science ◽

10.3389/fmars.2020.00626 ◽

2020 ◽

Vol 7 ◽

Cited By ~ 1

Author(s):

Marie Guilpin ◽

Véronique Lesage ◽

Ian McQuinn ◽

Pablo Brosset ◽

Thomas Doniol-Valcroze ◽

...

Keyword(s):

Prey Density ◽

Density Limit ◽

Energy Acquisition ◽

Blue Whales ◽

Limit Energy

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A note on the distribution and abundance of blue whales (Balaenoptera musculus) in the Central and Northeast North Atlantic

NAMMCO Scientific Publications ◽

10.7557/3.2703 ◽

2009 ◽

Vol 7 ◽

pp. 19 ◽

Cited By ~ 12

Author(s):

Daniel G Pike ◽

Gísli A Víkingsson ◽

Thorvaldur Gunnlaugsson ◽

Nils Øien

Keyword(s):

North Atlantic ◽

Line Transect ◽

Positive Trend ◽

Standard Line ◽

Balaenoptera Musculus ◽

Species Identity ◽

Detection Function ◽

Significant Positive Trend ◽

Northeast Atlantic ◽

Blue Whales

The distribution and abundance of blue whales (Balaenoptera musculus) was assessed from ship surveys conducted in the Central and Northeast Atlantic in 1987, 1989, 1995 and 2001. Blue whales were most commonly sighted off western Iceland, and to a lesser extent northeast of Iceland. They were very rare or absent in the Northeast Atlantic. Sightings were combined over all surveys to estimate the detection function using standard line transect methodology, with the addition of a covariate to account for differences between surveys. Total abundance was highest in 1995 (979, 95% CI 137-2,542) and lowest in 1987 (222, 95% CI 115-440). Uncertainty in species identity had little effect on estimates of abundance. There was a significant positive trend in abundance northeast of Iceland and in the total survey area.

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Temporal Variability of Cetaceans near Halifax, Nova Scotia

The Canadian Field-Naturalist ◽

10.22621/cfn.v120i1.252 ◽

2006 ◽

Vol 120 (1) ◽

pp. 93 ◽

Cited By ~ 2

Author(s):

Peter Simard ◽

Jennifer L. Lawlor ◽

Shannon Gowans

Keyword(s):

Nova Scotia ◽

North Atlantic ◽

Humpback Whales ◽

Eubalaena Glacialis ◽

Balaenoptera Acutorostrata ◽

Minke Whales ◽

North Atlantic Right Whales ◽

Early Fall ◽

Large Groups ◽

Blue Whales

Annual and seasonal trends in sightings of coastal cetaceans near Halifax, Nova Scotia, were studied using observations from whale watching and dedicated research vessels from late spring to early fall of 1996 to 2005. Four species of cetaceans routinely used the area during the summer: White-beaked and Atlantic White-sided dolphins (Lagenorhynchus albirostris and L. acutus), Harbour Porpoises (Phocoena phocoena), and Minke Whales (Balaenoptera acutorostrata). The dolphin species were temporally separated, with White-beaked Dolphins being common earlier in the summer than White-sided Dolphins. White-sided Dolphins were unusually abundant in 1997, and were found in larger groups (mean = 46.5 ± 46.19 sd) than Whitebeaked Dolphins (mean = 9.1 ± 5.19 SD). The area also appears to be an important habitat for dolphin calves and juveniles of both species. Fin Whales (B. physalus) were commonly observed in relatively large groups in 1997, but were uncommon or absent in other years. Humpback Whales (Megaptera novaeangliae), Blue Whales (B. musculus) and North Atlantic Right Whales (Eubalaena glacialis) were uncommon in the area, although Humpback Whales were sighted frequently in 1997. Increased numbers of White-sided Dolphins, Fin and Humpback whales in 1997 may be explained by increased prey abundance and decreased sea-surface temperatures.

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Blue whale (Balaenoptera musculus musculus) genome: population structure and history in the North Atlantic

10.22541/au.161842590.09830459/v1 ◽

2021 ◽

Author(s):

Sushma Jossey ◽

Oliver Haddrath ◽

Livia Loureiro ◽

Burton Lim ◽

Jacqueline Miller ◽

...

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

North Atlantic ◽

Conservation Strategies ◽

Balaenoptera Musculus ◽

Blue Whale ◽

Genetic Diversity And Structure ◽

Population Structuring ◽

The Impact ◽

Blue Whales

Knowledge of genetic diversity and structure is essential for developing conservation strategies for endangered species. The advances in museum genomics can assist in better understanding the effects of over-hunting on the genome by comparing historical to present-day samples. Blue whales were hunted to the point of near extinction in the mid-twentieth century. Herein, we use whole genome sequencing to elucidate the poorly understood population structure of North Atlantic (NA) blue whales (Balaenoptera musculus musculus). We generated a de novo genome assembly of 2.49 Mbp for a NA blue whale (N50 of 1.46 Mb) to analyze 19 whole genomic sequences and 28 complete mitochondrial genomes. We included present-day and historical samples (earliest from 1900) from the Atlantic and Antarctica to understand the impact of whaling on the genetic diversity. We found low population structuring, but high genetic diversity, suggesting a single, panmictic population in the NA. We identified gene flow from fin whale to blue whales, accounting for ~3.5% of the genome. Introgression between blue and fin whales was observed in all the present-day samples but were lacking in some whales sampled early in the 20th century, which suggests increasing disruption in mate choice concomitant with decline in blue whale population. We also assembled and analyzed the transcriptome and revealed positive selection of oncogenes, which may be involved in reduced cancer rates in this largest of mammals ever known. Our sequencing and population structuring studies provide a genomic framework to guide ongoing conservation strategies for this iconic species.

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