Occurrence of killer whale Orcinus orca rake marks on Eastern Canada-West Greenland bowhead whales Balaena mysticetus

Polar Biology ◽  
2013 ◽  
Vol 36 (8) ◽  
pp. 1133-1146 ◽  
Author(s):  
N. R. Reinhart ◽  
S. H. Ferguson ◽  
W. R. Koski ◽  
J. W. Higdon ◽  
B. LeBlanc ◽  
...  
2021 ◽  
Vol 8 ◽  
Author(s):  
Steven H. Ferguson ◽  
Jeff W. Higdon ◽  
Patricia A. Hall ◽  
Rikke Guldborg Hansen ◽  
Thomas Doniol-Valcroze

Bowhead whales (Balaena mysticetus L., 1758) of the Eastern Canada-West Greenland population have been hunted by Inuit for millennia. Significant commercial harvests, conducted by European and American whalers for about 400 years, ended ca. 1915. A small co-managed subsistence harvest from this population has occurred inconsistently in Canada and Greenland, since 1996 and 2009, respectively. Since near extirpation from commercial whaling, population size has increased and the Inuit subsistence hunt now requires a harvest management framework that incorporates knowledge of abundance trends, population dynamics, and carrying capacity. Here, we use a model estimate of pre-commercial exploitation abundance to approximate carrying capacity and develop a management framework with reference points and corresponding stock status zones. When applied to recent abundance estimates, our framework indicates that the population is likely within the healthy (N50–N70) zone. Thus, an appropriate management objective is to support continued population increase, with concurrent marginal harvesting, while maintaining the population level above the target reference point (N70) of ca 12,000 whales. However, there remains large uncertainty about current population size and growth rate. The resulting data gaps require a plan for future research to monitor this population in the context of climate changes.


2020 ◽  
Vol 643 ◽  
pp. 197-217 ◽  
Author(s):  
SME Fortune ◽  
SH Ferguson ◽  
AW Trites ◽  
B LeBlanc ◽  
V LeMay ◽  
...  

Climate change may affect the foraging success of bowhead whales Balaena mysticetus by altering the diversity and abundance of zooplankton species available as food. However, assessing climate-induced impacts first requires documenting feeding conditions under current environmental conditions. We collected seasonal movement and dive-behaviour data from 25 Eastern Canada-West Greenland bowheads instrumented with time-depth telemetry tags and used state-space models to examine whale movements and dive behaviours. Zooplankton samples were also collected in Cumberland Sound (CS) to determine species composition and biomass. We found that CS was used seasonally by 14 of the 25 tagged whales. Area-restricted movement was the dominant behaviour in CS, suggesting that the tagged whales allocated considerable time to feeding. Prey sampling data suggested that bowheads were exploiting energy-rich Arctic copepods such as Calanus glacialis and C. hyperboreus during summer. Dive behaviour changed seasonally in CS. Most notably, probable feeding dives were substantially shallower during spring and summer compared to fall and winter. These seasonal changes in dive depths likely reflect changes in the vertical distribution of calanoid copepods, which are known to suspend development and overwinter at depth during fall and winter when availability of their phytoplankton prey is presumed to be lower. Overall, CS appears to be an important year-round foraging habitat for bowheads, but is particularly important during the late summer and fall. Whether CS will remain a reliable feeding area for bowhead whales under climate change is not yet known.


2020 ◽  
Vol 11 ◽  
Author(s):  
Thomas Doniol-Valcroze ◽  
Jean-François Gosselin ◽  
Daniel G. Pike ◽  
Jack W. Lawson ◽  
Natalie C. Asselin ◽  
...  

The hunting of bowhead whales (Balaena mysticetus) is an integral part of Inuit culture. An up-to-date abundance estimate of the entire Eastern Canada – West Greenland (EC-WG) bowhead population is necessary to support sustainable management of this harvest. The High Arctic Cetacean Survey (HACS) was conducted in August 2013, primarily to update abundance estimates for known stocks of Baffin Bay narwhal (Monodon monoceros). As the ranges of narwhal and bowhead largely overlap, the survey area was expanded to cover the summer range of bowhead whales. Bowhead whale abundance was estimated using 3 aircraft to cover the large survey area within a short time frame. Distance sampling methods were used to estimate detection probability away from the track line. Double platform with mark-recapture methods were used to correct for the proportion of whales missed by visual observers on the track line (perception bias). Abundance in Isabella Bay, an area known for high bowhead density, was estimated using density surface modelling to account for its complex shape and uneven coverage. Estimates were corrected for availability bias (whales that were not available for detection because they were submerged when the aircraft passed overhead) using a recent analysis of satellite-linked time depth recorders transmitting information on the diving behaviour of bowhead whales in the study area in August of the same survey year. The fully corrected abundance estimate for the EC-WG bowhead whale population was 6,446 (95% CI: 3,838–10,827). Possible sources of uncertainty include incomplete coverage and the diving behaviour of bowhead whales. These results confirm earlier indications that the EC-WG stock is continuing to recover from past overexploitation.


2011 ◽  
Vol 14 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Ø Wiig ◽  
MP Heide-Jørgensen ◽  
C Lindqvist ◽  
KL Laidre ◽  
LD Postma ◽  
...  

ARCTIC ◽  
1994 ◽  
Vol 47 (3) ◽  
Author(s):  
John Craighead George ◽  
L. Michael Philo ◽  
Katherine Hazard ◽  
David Withrow ◽  
Geoffry M. Carroll ◽  
...  

Polar Biology ◽  
2020 ◽  
Vol 43 (11) ◽  
pp. 1669-1679
Author(s):  
Amy L. Willoughby ◽  
Megan C. Ferguson ◽  
Raphaela Stimmelmayr ◽  
Janet T. Clarke ◽  
Amelia A. Brower

1996 ◽  
Vol 15 (2) ◽  
pp. 115-125 ◽  
Author(s):  
Randall R. Reeves ◽  
Mads Peter Heide-Jørgensen

2020 ◽  
Vol 6 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Brent G. Young ◽  
Sarah M.E. Fortune ◽  
William R. Koski ◽  
Stephen A. Raverty ◽  
Ricky Kilabuk ◽  
...  

Accounts of killer whale (Orcinus orca) predation on marine mammals in the Canadian Arctic are relatively uncommon. Although second-hand reports of killer whale predation events in the Arctic are more common in recent years, these observations are generally poorly documented and the outcome of attacks are often unknown. On 12 August 2016, a floating bowhead whale (Balaena mysticetus) carcass was found off-shore in Cumberland Sound, Nunavut — presumably predated by killer whales that were sighted in the area. Inspection of the carcass revealed injuries consistent with published accounts of killer whale predation on large whales and observations of killer whale predation on bowheads described in Inuit traditional knowledge. The bowhead was male, 6.1 m long in good nutritional condition and estimated between 14 and 16 months old. As a recently weaned yearling, this whale would have been highly vulnerable to killer whale predation. With decreasing summer sea ice making some areas of the Arctic more accessible, the incursion and presence of killer whales in the Arctic is expected to increase. A better understanding of Arctic killer whale predation pressure is needed to predict the potential impact they will have on the eastern Canada–west Greenland bowhead population as well as on other marine mammal prey.


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