Principles affecting the size of pink and chum salmon populations in British Columbia ...
Changes in population size are governed by the birthrate, the sex ratio and the death rate. In pink salmon the average egg-production per female is about 1700 and variations from this average are insufficient to account for observed changes in adult populations. The sex ratio is approximately 50-50....
| Main Author: | |
|---|---|
| Format: | Text |
| Language: | English |
| Published: |
University of British Columbia
2012
|
| Subjects: | |
| Online Access: | https://dx.doi.org/10.14288/1.0302621 https://doi.library.ubc.ca/10.14288/1.0302621 |
| Summary: | Changes in population size are governed by the birthrate, the sex ratio and the death rate. In pink salmon the average egg-production per female is about 1700 and variations from this average are insufficient to account for observed changes in adult populations. The sex ratio is approximately 50-50. Survival during the freshwater phases of the life cycle has been found to vary from approximately 1% to 24%,the average survival being significantly different in different streams. Variation is relatively greater in streams in which average survival is low. Natural survival in the ocean is considered, to average about 5% of the number of young fish reaching the sea. In the central region of the British Columbia coast the annual catch averages about 60% of the adult fish, this percentage being relatively constant for both small and large runs. Pink salmon maturing in "even" and "odd" years represent separate populations. These populations vary in size independently but may maintain a relatively constant ratio for ... |
|---|