Research Document - 2001/106
A proposed MPA boundary identification process for reproductive refugium establishment, using lingcod (Ophiodon elongatus) as an example focal species
By Jamieson, G.S., Dixon, S.
Abstract
The boundaries of any MPA are likely to be a function of local bathymetry, management objectives for the area, and the biological characteristics of particular focal species, if any, identified. For many MPAs, there may be an obvious bathymetric outer boundary (e.g., a bay, reefs around an isolated island, etc.) but others might be established on a section of coast of relatively homogenous bathymetry, for which recommendations of an outer boundary for the MPA may have to depend solely on the latter two criteria. Here, we consider how the boundaries of a potential MPA designed to serve as a reproductive refugium for lingcod (Ophiodon elongatus), a likely potential focal species in British Columbia, might be determined today from a science perspective, and consider the nature of the biological data that would be required to rationalise such a boundary.
Through our literature review for lingcod, a number of important information gaps for this species were identified. Firstly, there is no current estimate of the minimum numerical abundance of lingcod required to ensure an identified desired population reproductive potential. Secondly, to estimate the size of a no-harvest area required to sustain a specified desired lingcod population size, information is needed on the densities of individuals (male or female) by size that can be supported in different habitats, and the dispersal characteristics of individuals by size, neither of which are well described for lingcod. Due to this lack of information, we estimated MPA boundaries for such a hypothetical lingcod refugium based on the assumptions that: 1) an appropriate desired protected population size would be present along an arbitrary six km of longshore rocky shoreline, 2) that this population would be centred within the potential MPA area, and 3) that the average home range for lingcod over one year is a meaningful criterion to determine the distance the MPA's "no-harvest" boundary should be from the edge of the lingcod population desired to be fully protected.
With these assumptions, a refugium MPA for lingcod that would protect about 95% of the population would extend 34 km in any direction from the identified core lingcod habitat. Secondly, given that there is no documented history on the use of MPAs in Canada as a management tool for population rebuilding or reestablishment, if such MPAs were to be established for this purpose, appropriate follow-up monitoring will be required so that adaptive management can be implemented. Our main recommendation is that since establishing an MPA for the purpose of rebuilding depleted fish stocks requires considerable species-specific biophysical data, managers are urged to identify candidate species at the earliest possible time so that the appropriate available data can be assessed and, if deemed deficient, additional science data obtained.
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