Confidence intervals for fish out-migration estimates using stratified trap efficiency methods

Marked fish placed above a smolt trap allow fisheries biologists to estimate the efficiency of the trap and hence to estimate the number of smolts migrating past the trap. We compared stratified maximum likelihood estimators and confidence intervals of total numbers of fish migrating to two other well-known estimators and associated confidence intervals using simulation. The Bailey adjusted Lincoln-Petersen estimator and its bootstrap confidence interval performed well overall.