Population Dynamics of Western Arctic Bowhead Whales ( Balaena mysticetus )
Leslie-type projection matrices were used to model the western Arctic bowhead whale (Balaena mysticetus) population in two stages: (1) from 1848 to 1970 and (2) from 1970 to 2000. Several constraints were imposed on adult and immature survival rates, and several assumptions were made about combinati...
| Published in: | Canadian Journal of Fisheries and Aquatic Sciences |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1984
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/f84-058 http://www.nrcresearchpress.com/doi/pdf/10.1139/f84-058 |
| Summary: | Leslie-type projection matrices were used to model the western Arctic bowhead whale (Balaena mysticetus) population in two stages: (1) from 1848 to 1970 and (2) from 1970 to 2000. Several constraints were imposed on adult and immature survival rates, and several assumptions were made about combinations of age through which immature survival applies (a), age at sexual maturity (m), and maximum age (w). Fecundity was derived by assuming that the population was stationary in 1848 (start of commercial exploitation). Estimates of numbers of animals killed and struck and lost, as well as an assumed mortality rate for whales struck and lost, were used to solve for the 1848 population size assuming that the 1970 level was 4000 bowheads. The 1970 level (4000) was then projected forward to the year 2000 with constant kill regimes for 1983–2000 of 0, 20, and 40 animals per year. Results indicate that there is an apparent incompatibility between the observed proportion of immature whales in the population and the proportions predicted by population modeling. Improved estimates of calf production and of the proportion of immature bowheads in the population are therefore needed. Calculated maximum net productivity rate is very sensitive to adult survival rate and thus, accurate estimates of the current growth rate of the bowhead whale population are not possible at present. Due to the many uncertainties about relevant biological features of the population, it would be prudent to restrict future total removals to no greater than the levels prior to 1970. |
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