Reliability of indicators of decline in abundance.

Although there are many indicators of endangerment (i.e., whether populations or species meet criteria that justify conservation action), their reliability has rarely been tested.

Cycles, stochasticity and density dependence in pink salmon population dynamics.

Complex dynamics of animal populations often involve deterministic and stochastic components. A fascinating example is the variation in magnitude of 2-year cycles in abundances of pink salmon (Oncorhynchus gorbuscha) stocks along the North Pacific rim. Pink salmon have a 2-year anadromous and semelparous life cycle, resulting in odd- and even-year lineages that occupy the same habitats but are reproductively isolated in time.

Bayesian decision analysis for evaluating management options to promote recovery of a depleted salmon population.

The endangered population of sockeye salmon (Oncorhynchus nerka) in Cultus Lake, British Columbia, Canada, migrates through commercial fishing areas along with other, much more abundant sockeye salmon populations, but it is not feasible to selectively harvest only the latter, abundant populations. This situation creates controversial trade-offs between recovery actions and economic revenue. We conducted a Bayesian decision analysis to evaluate options for recovery of Cultus Lake sockeye salmon.

Valuing freshwater salmon habitat on the west coast of Canada.

Changes in land use can potentially reduce the quality of fish habitat and affect the economic value of commercial and sport fisheries that rely on the affected stocks. Parks and protected areas that restrict land-use activities provide benefits, such as ecosystem services, in addition to recreation and preservation of wildlife. Placing values on these other benefits of protected areas poses a major challenge for land-use planning.

Tests of the role of a nuclear polyhedrosis virus in the population dynamics of its host, douglas-fir tussock moth, Orgyia pseudotsugata (Lepidoptera: Lymantriidae).

Outbreaks of the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), have recurred periodically, at 7- to 10-year intervals, since the first recorded observation in 1916 in Chase, British Columbia, Canada. Anderson and May (1981) hypothesized that microparasites are responsible for the periodic population fluctuations of some defoliating insects. We chose the association between the Douglas-fir tussock moth and a viral disease, caused by a nuclear polyhedrosis virus (NPV), to test whether their model, and variants thereof, can predict the observed population cycles.