Research Document - 2013/022
Recovery Potential Modelling of Hickorynut (Obovaria olivaria) in Canada
By J.A.M. Young and M.A. Koops
Abstract
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed Hickorynut (Obovaria olivaria) as Endangered in Canada (COSEWIC 2011). In support of a recovery potential assessment (RPA) we present population modelling of Hickorynut, including its dependence on a host fish (Lake Sturgeon) for its parasitic phase. Species and population specific information on the life history of Hickorynut was not sufficient to parameterize a species specific model of Hickorynut. Instead we used general knowledge of the life cycle and vital rates of unionid mussels to estimate the sensitivity of population growth to changes in the survival, growth, and fecundity of Hickorynut. We also explored how host-dependence affects mussel population abundance. Model results show that Hickorynut population growth is likely most sensitive to proportional perturbations that affect juvenile or adult survival. Modelling showed that when a mussel population is stable or growing, mussel population abundance is determined by: host abundance (if stable), host population trajectory, the life history of the mussel, and host-specific probability of glochidial attachment. When the host population was stable, a predictable, stable mussel abundance was reached. This equilibrium was sensitive to the life history of Hickorynut, and was very sensitive to the availability of juvenile Lake Sturgeon as hosts but less so to the availability of adult hosts.
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