Effects of environmental covariates and density on the catchability of fish populations and interpretation of catch per unit effort trends

摘要: Abstract Quantifying temporal and spatial trends in abundance or relative is required to evaluate effects of harvest changes habitat for exploited endangered fish populations. In many cases, the proportion population stock that captured (catchability capture probability) unknown but often assumed be constant over space time. We used data from a large-scale mark-recapture study extent variation, density, size, environmental covariates, on probability rainbow trout ( Oncorhynchus mykiss ) Colorado River, AZ. Estimates boat electrofishing varied 5-fold across five reaches, 2.8-fold range densities were encountered, 2.1-fold 19 trips, 1.6-fold size classes. Shoreline angle turbidity best covariates explaining variation reaches trips. Patterns driven by gear efficiency aggregation, latter was more important. Failure account density when translating historical catch per unit effort time series into abundance, led 2.5-fold underestimation maximum period record, resulted unreliable estimates change critical years. Catch surveys have utility monitoring long-term are too imprecise potentially biased response modest fishing effort.