COSEWIC Assessment and Status Report on the Rougheye Rockfish sp. type I and sp. type II in Canada
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- Lists of Figures and Tables
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status Designations
- Technical Summary
- Acknowledgements & Authorities Consulted and Information Sources
- Biographical Summary of the Report Writers and Collections Examined
Limiting Factors and Threats
The primary threat to the population stems from overfishing long-lived species that inhabit the upper continental slope. Given the benthic nature of the rougheye rockfish species pair, both trawl and hook and line fleets affect this species. An apparent reduction in older age classes (Figure 10) from 1996 to 2003 may indicate a significant fishing pressure, and catch curve analysis based on proportions at age suggests that the mean Z doubled during this period, but these changes may be due to non-representative sampling. The apparent doubling of total mortality is not consistent with the apparent stability or increase in CPUE indices in the same period.
The recently discovered existence of two species within what was formerly known as rougheye rockfish, Sebastes aleutianus (Jordan and Evermann, 1898), and the lack of knowledge of distribution and threats for the two species, constitutes a threat in itself. Cryptic species of this kind increase the risk of loss of unrecognized genetic diversity. Considerable additional scientific work will be required to describe the relative abundance of the two species in Canadian waters, their distribution, and the impacts of fisheries (and potentially other threats) on each.
Overall, this species pair remains poorly understood from either a biological or population perspective. Recently initiated synoptic groundfish surveys should help to improve the information base on trends in this species pair within a few years.
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