scholarly journals Quantifying marine mammal hotspots in British Columbia, Canada

Ecosphere ◽  
2017 ◽  
Vol 8 (7) ◽  
pp. e01884 ◽  
Author(s):  
Gillian K. A. Harvey ◽  
Trisalyn A. Nelson ◽  
Caroline H. Fox ◽  
Paul C. Paquet
Keyword(s):  
British Columbia ◽  
Marine Mammal

A study of the behavior of Dall's porpoise (Phocoenoides dalli) in the Johnstone Strait, British Columbia

1987 ◽  
Vol 65 (3) ◽  
pp. 736-744 ◽  
Author(s):  
Thomas A. Jefferson
Keyword(s):  
British Columbia ◽  
Group Size ◽  
Swimming Speed ◽  
Marine Mammal ◽  
Time Of Day ◽  
Observation Point ◽  
Killer Whales ◽  
Mean Size ◽  
Westward Movement ◽  
Slow Rolling

The behavior of Dall's porpoise was studied in the western Johnstone Strait, British Columbia, during the summer of 1984. Observations and theodolite trackings were made from a cliff-top observation point on West Cracroft Island. Dall's porpoise was the second most common marine mammal in the study area, being seen on 63% of the days, and it was reported to be a year-round resident of the Strait. Three types of surfacing behavior were observed, with slow rolling occurring in 97% of the sightings. Swimming speed of slow rolling porpoises was 5.1 ± 0.83 (SD) km/h (n = 18). Dives during travel averaged 35.9 ± 26.52 (SD) s (n = 10). Deep vertical dives lasted 2 to 4 min for adults and up to 2 min for calves, and were presumed to be associated with feeding. Westward movement predominated. Dall's porpoises usually showed no obvious reaction to resident killer whales, but apparently swimming speed increases when killer whales are within 2 km. Group sizes ranged from one to over five animals (mean size = 2.6 ± 1.05 (SD), n = 68). Groups that included calves tended to be larger than adult-only groups. Neither direction of travel nor time of day were significantly related to group size. The population appears to contain a high percentage of cow–calf pairs, and this suggests that the study area may be used as a calving area during the summer.

Potential limits to anthropogenic mortality of small cetaceans in coastal waters of British Columbia

2008 ◽  
Vol 65 (9) ◽  
pp. 1867-1878 ◽  
Author(s):  
Rob Williams ◽  
Anna Hall ◽  
Arliss Winship
Keyword(s):  
British Columbia ◽  
Marine Mammal ◽  
Conservation Status ◽  
The United States ◽  
Population Increase ◽  
Future Research ◽  
Abundance Estimate ◽  
Favourable Conservation Status ◽  
The Baltic ◽  
Species Specific

Small cetaceans are by-caught in salmon gillnet fisheries in British Columbia (BC) waters. In Canada, there is currently no generic calculation to identify when management action is necessary to reduce cetacean bycatch below sustainable limits. We estimated potential anthropogenic mortality limits for harbour ( Phocoena phocoena ) and Dall’s ( Phocoenoides dalli ) porpoises and Pacific white-sided dolphins ( Lagenorhynchus obliquidens ) using quantitative objectives from two well-established frameworks for conservation and management (the United States’ Marine Mammal Protection Act and the Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas), which are similar to some management objectives developed for marine mammal stocks elsewhere in Canada. Limits were calculated as functions of (i) a minimum abundance estimate (2004–2005); (ii) maximum rate of population increase; and (iii) uncertainty factors to account for bias in abundance estimates and uncertainty in mortality estimates. Best estimates of bycatch mortality in 2004 and 2005 exceeded only the most precautionary limits and only for porpoise species. Future research priority should be given to determining small cetacean stock structure in BC and refining species-specific entanglement rates in these and other fisheries. The approach offers a quantitative framework for Canada to meet its stated objectives to maintain favourable conservation status of cetacean populations.

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