Research Document - 1999/190

Review of Status of Northern, or Pinto, Abalone, Haliotis kamtschatkana, in Canada.

By G.S. Jamieson

Abstract

Jamieson (1989) reviewed the status of northern, or pinto, abalone (Haliotis kamtschatkana) in British Columbia, Canada, but while the paper was accepted and reviewed by COSEWIC in April, 1988, no status could be assigned, as at that time COSEWIC had no mandate for invertebrates. COSEWIC's mandate changed in 1994, however, and COSEWIC is now able to assign status to molluscs. Here, I update the review of the status of this species in relation to recognised threats which might lead to this species' extirpation in Canada. Threats are identifiable, but the risks of population extinction associated with them are impossible to quantify. For example, natural northern abalone population size and size frequency structure equilibria are unknown (recent prefishery levels may have been high because of earlier abalone predator (sea otter) extirpation); unquantifiable but possibly substantial continued illegal northern abalone harvest in British Columbia, even though all northern abalone fisheries have been closed since 1990; and an unknown overall spatial abundance distribution, with time-series abundance data only available from a limited number (53) of index sites. Nevertheless, available data indicate continued declining abundance following fishery closure, and as sea otters slowly expand their range, natural mortality rate of northern abalone in areas where sea otters do not now occur will increase. Biological data suggests that the absolute abundance of adult abalone in close proximity to each other affects spawning success (external gamete fertilisation), and that larval dispersal range from concentrations of abalone may be quite limited. Individual concentrations of abalone may thus be largely self-sustaining, and potentially vulnerable to local extirpation over time if they experience a sustained high adult mortality. Monitoring of index sites, where abalone previously occurred, shows an increased frequency of sites which have no abalone now.

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