Research Document - 2003/047

Formulation of an Incidental Harm Permit Strategy for wolffish species (Anarhichadidae).

By Simpson, M.R., Kulka, D. W.

Abstract

In anticipation of the proclamation of Species at Risk Act, this paper examines conditions that would be included in an Incidental harm permit strategy for northern, spotted and striped wolffish. This work has implications for other marine fish that may be listed in the future given that wolffish are typically data deficient. As well, the marine environment in which it lives is poorly understood making the formulation of conditions for Incidental Harm Permits difficult. In this light, we review critical knowledge on wolffish biology, including distribution, abundance, and critical habitat, as well as patterns in fisheries mortality which must be known in order to determine the IHP conditions under which wolffish could be captured. Pre-conditions for the issuance of an IHP is demonstrating that incidental capture, or habitat destruction, will not prevent the recovery of the species. In the case of wolffish, and other poorly understood species, estimates of population growth and viability under various levels of by-catch will be difficult, if impossible to determine. For non-directed species, part of the IHP would constitute strategies such as spatial/temporal closures and gear restrictions that would minimize incidental capture in fisheries directed for other species. In this paper we discuss the efficacy of each of these potential measures. Due to their widespread distribution, diverse habitat preferences, and lack of particular spawning or feeding aggregations spatial closures are considered to be an ineffective method to reduce wolffish by-catch at this time. As well, since specific information on critical periods in the life history of these species is unknown, the efficacy of temporal closure is also limited. At present, wolffish live-release, which is particularly feasible in fisheries where the gear does not harm wolffish has been considered presently to be the most viable strategy to reduce wolffish mortality. Alternatively, consideration could be given to the imposition of a catch limit for each species based on an exploitation index derived from a ratio of catch to biomass index observed in recent years.

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