Effectiveness of enforcement to deter illegal angling harvest of northern pike in Alberta

We studied anglers' perceptions of an enhanced enforcement strategy and the effects of this strategy on the illegal harvest of northern pike Esox lucius at recreational fisheries in Alberta. The strategy was designed by Alberta enforcement officers and consisted of varying patrol frequency and strongly worded warning posters. Monitoring effects of this strategy at nine popular Alberta lakes during 2001 and 2002 showed that intensive patrol events did not change anglers' perceptions of enforcement. Anglers' perceptions of detection (i.e., certainty of punishment) increased with enforcement effort, but not with the use of warning posters. Anglers' perceptions of penalties (i.e., severity of punishment) increased with the use of signs, but not with increased patrol effort. We observed a tendency toward reduced illegal harvest at lakes where anglers perceived high deterrence (defined as the product of certainty and severity of punishment), although anglers consistently overestimated the actual risks of detection. Anglers perceived that the chance of detection increased as enforcement effort increased, with an asymptotic maximum perception when officers contacted more than 3% of anglers. These results suggest that officer efficiency in deterring anglers' illegal behavior at these lakes is optimized by applying no more than this level of enforcement effort.