An interrupted time series approach to assess Marine Protected Area impacts on recreational fishing licence sales

Abstract

Marine Protected Areas (MPAs) are increasingly used as a management and conservation strategy. However, the effects of MPA implementation (i.e. restrictions on extractive use) on recreational fishers' spatial behaviour are often not considered. Spatial shifts in fishing pressure and which port fishers choose to fish from can have ecological and economic impacts. Therefore, it is critical that MPA impacts on recreational fishers are adequately investigated and weighed against potential conservation benefits from MPA designation. The State of Oregon, USA, has a system of five no-take marine reserves (MRs) with adjacent limited-take MPAs. This study used an interrupted time series approach to investigate how fishing licence sales were impacted by MR implementation. This study found that recreational fishers near only one MR were potentially adversely impacted by MR implementation. The proportion of coastal licence sales near Redfish Rocks MR displayed an immediate sustained 47.1% proportional decrease following reserve implementation. Conversely, there was a 0.5% proportional increase in monthly demand for licence sales near Otter Rock and Cascade Head MRs. This study suggests that most MRs in Oregon were designated in a manner that limited significant adverse impacts to some ocean users, a specified MR objective. The process of MR planning in Oregon, which involved considerable public input, could be used as an example for MR designation in other similar settings. However, when a potential MR site and adjacent town's conditions match those at Redfish Rocks MR, there may be adverse socio-economic impacts that should be weighed against potential ecological benefits. This study also demonstrates the application of an interrupted time series approach. When sufficient data are available, this is a robust approach that addresses numerous shortfalls of traditional MPA impact evaluations.