Evaluation of mechanically improved Conibear 220 traps to quickly kill fisher (Martes pennanti) in simulated natural environments.

Mechanically improved Conibear 220 traps failed to render irreversibly unconscious in < or = 3 min fishers single-struck in the head-neck region, or double-struck in the neck and thorax regions. Although the Conibear 220 trap is often recommended as an alternative to the steel leghold trap, it is unlikely that it has the potential to humanely kill fisher.