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An analysis of historic (1908-1967) whaling records from British Columbia, Canada Gregr, Edward James
Abstract
Analysis of data recorded from 24,862 whales killed by British Columbia coastal whaling stations between 1908 and 1967 revealed trends in the abundance, sex ratios, age structure and the distance from shore of sperm (Physeter macrocephalus), sei (Balaenoptera borealis), fin (Balaenoptera physalus), humpback (Megaptera novaeangliae) and blue (Balaenoptera musculus) whales. Trends in the relationships between records of where the whales were killed (n=l 0,275) and a simple oceanographic model were used to build generalized linear models, from which predictions of whale habitat were generated. The catch data were analyzed using annual and monthly mean values. Monthly and annual variation in whaling effort was deduced from accounts of the history of British Columbia coastal whaling, and biases arising from changes in effort were considered in the interpretation of the results. Predictive habitat models were produced at annual and monthly time scales based on an initial analysis of the univariate relationships between whale presence-absence and six independent predictor variables (depth, slope, depth class, sea surface temperature and salinity, and month). During the later years of whaling (1948 to 1967), the mean lengths of captured whales declined significantly in all five species and pregnancy rates dropped to near zero in fin, sei and blue whales. Monthly patterns in numbers killed revealed a summer migration of sei and blue whales past Vancouver Island, and confirms anecdotal suggestions that local populations of fin and humpback whales once spent extended periods in the coastal waters of British Columbia. Furthermore, the data strongly suggest that sperm whales mated (April-May) and calved (July-August) in British Columbia's offshore waters. The habitat models showed that the continental slope and a large area off the northwest coast Vancouver Island may represent critical habitat for sei, fin and male sperm whales. Female sperm whales, blue and humpback whales appeared less sensitive to the predictor variables, however, the sample size for these groups was significantly smaller than for the other species. The habitat predictions lend support to the hypotheses regarding sperm whale breeding and predict humpback whale habitat in sheltered bays and straits throughout coastal British Columbia. The habitat models also generated hypotheses about the relationships and processes that link these whale species to their environment. The historic whaling records revealed much about the migratory behaviour and distribution of the large whales species as they once were, and may continue to be, in the Northeast Pacific. Verifying the persistence of these trends in the remnant populations is a necessary and logical next step.
Item Metadata
Title |
An analysis of historic (1908-1967) whaling records from British Columbia, Canada
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2000
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Description |
Analysis of data recorded from 24,862 whales killed by British Columbia coastal whaling stations
between 1908 and 1967 revealed trends in the abundance, sex ratios, age structure and the distance
from shore of sperm (Physeter macrocephalus), sei (Balaenoptera borealis), fin (Balaenoptera
physalus), humpback (Megaptera novaeangliae) and blue (Balaenoptera musculus) whales. Trends
in the relationships between records of where the whales were killed (n=l 0,275) and a simple
oceanographic model were used to build generalized linear models, from which predictions of whale
habitat were generated.
The catch data were analyzed using annual and monthly mean values. Monthly and annual variation
in whaling effort was deduced from accounts of the history of British Columbia coastal whaling, and
biases arising from changes in effort were considered in the interpretation of the results. Predictive
habitat models were produced at annual and monthly time scales based on an initial analysis of the
univariate relationships between whale presence-absence and six independent predictor variables
(depth, slope, depth class, sea surface temperature and salinity, and month).
During the later years of whaling (1948 to 1967), the mean lengths of captured whales declined
significantly in all five species and pregnancy rates dropped to near zero in fin, sei and blue whales.
Monthly patterns in numbers killed revealed a summer migration of sei and blue whales past
Vancouver Island, and confirms anecdotal suggestions that local populations of fin and humpback
whales once spent extended periods in the coastal waters of British Columbia. Furthermore, the data
strongly suggest that sperm whales mated (April-May) and calved (July-August) in British
Columbia's offshore waters.
The habitat models showed that the continental slope and a large area off the northwest coast
Vancouver Island may represent critical habitat for sei, fin and male sperm whales. Female sperm
whales, blue and humpback whales appeared less sensitive to the predictor variables, however, the
sample size for these groups was significantly smaller than for the other species. The habitat
predictions lend support to the hypotheses regarding sperm whale breeding and predict humpback
whale habitat in sheltered bays and straits throughout coastal British Columbia. The habitat models
also generated hypotheses about the relationships and processes that link these whale species to their
environment.
The historic whaling records revealed much about the migratory behaviour and distribution of the
large whales species as they once were, and may continue to be, in the Northeast Pacific. Verifying
the persistence of these trends in the remnant populations is a necessary and logical next step.
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Extent |
5642402 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-07-06
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0074856
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2000-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.