Longspine thornyhead (Sebastolobus altivelis) COSEWIC assessment and status report: chapter 8
Limiting Factors and Threats
The primary threat to the population stems from overfishing a deep-water species that occupies a low-productivity environment. From 1996-2005, the observer program (PacHarvTrawl database) recorded the capture of approximately 6,564 t of longspine thornyhead (57.6 million fish). Since the inception of the quota fishery in 1996, the composite coastwide index has declined by 8.25%/y for a total decline of 50% over eight years. Schnute et al. (2004) estimated similar declines for various models and assumptions (see their Table 9.1, p. 41). These numbers may indicate the “fishing-down” of a previously unexploited species (removal of accumulated biomass, theoretically associated with increased productivity due to reduced density). Recent reports from the industry suggest that the longspine thornyhead fishery has become increasingly less attractive commercially due to falling market prices for thornyheads, increasing fuel costs and the high exchange rate for the Canadian dollar. Indeed, the 2004-05 catches reflect this (Table 3), especially given the recent annual quotas of 635 t (Haigh et al. 2005). However, future conditions in the fishery cannot be predicted.
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