Deterrents and nudges improve compliance in Greenland's Atlantic salmon (Salmo salar) fishery

Fishers reporting all of their catch is key to estimating population viabilities of vulnerable, highly migratory fish stocks. However, fishery managers find it difficult to ensure that this reporting behavior takes place consistently. Wild Atlantic salmon (Salmo salar) are a highly migratory and internationally contested species with a threatened conservation status. Greenland manages a fishery for Atlantic salmon, and its coastline serves as a key feeding ground in the life history of Atlantic salmon. However, salmon catch is underreported by fishers, even though they are required to report. Deterring noncompliant behavior with penalties and sending short message service (SMS) messages have been shown to increase compliance, but no known studies test their effect on compliance with catch reporting requirements. We evaluated two interventions for their effect on salmon catch reporting behavior among Greenland's salmon fishers. Salmon fishers were 41% more likely to report (p < 0.00) once a deterrence-based intervention was implemented. Fishers who received SMS reminders were 6% more likely to report salmon catch (p < 0.1). These results highlight the complementarity of nudges and command-and-control interventions to increase compliance with catch reporting requirements.