To sample or not to sample: An ongoing issue at the bonneville dam adult fish trap on the Columbia River

Chinook, sockeye, and steelhead have been sampled at the Bonneville Dam adult fish trap since 1985.  Trapping data is used by the (international) Pacific Salmon Commission and regional harvest managers to set fishing seasons, forecast run sizes, reconstruct runs, and estimate impacts on endangered species.  In recent years, a regional fish passage entity has imposed increasingly more stringent conditions on sampling due to concerns about fish density in as well the health of fish sampled, particularly above 21.1C.  This has greatly reduced sample sizes and biased our sample, resulting in harvest managers being forced to use parameter estimates of uncertain accuracy and of much lower precision.                The conflict has escalated to high levels regionally, raising important questions about concerns for the fish being sampled, versus the impact of attempting to manage runs with inadequate data.  The fish passage entity points to other sources of bias in sampling and other catch sampling to justify imposing additional sampling restrictions and biases.  These issues will be laid out, as well as results of analyses of PIT tagged fish passing through Bonneville Dam which provide valuable information on potential biases as well as potential impacts on fish sampled at higher temperatures.