Exaggeration of Walleye Catches by Alberta Anglers

Abstract

I studied anglers’ exaggeration of catches of walleyes Stizostedion vitreum at Alberta sport fisheries to determine whether trends in reported catches were indicative of actual trends. To quantify anglers’ exaggeration, I compared the ratios of protected-length to legal-length walleyes as reported by anglers with similar ratios confirmed from test angling at 22 walleye sport fisheries from 1991 to 2000. Overall, anglers reported catching 2.2 times more protected-length walleyes per legal-length walleyes than were caught in the test-angling fisheries. Exaggeration in catches was not constant but increased exponentially with decreasing catch rate. On-site exaggeration, in combination with further exaggeration in mail surveys, results in the reported catch rate declining at a lower rate than the actual catch rate, thereby causing a perception of hyperstability in the fishery. Hyperstability has profound implications for biologists who manage fisheries based on reported data because reported catch rates may provide little warning of a fisheries collapse.