The number of protected areas that restrict or prohibit harvest of wild populations is growing. However, the underlying assumption that harvest has actually ceased is rarely tested directly. Determining whether illegal harvest (poaching) has continued in a protected area is important to planning enforcement and adaptive management.

This study estimated harvest rates for fish species inside marine protected areas (MPAs) and non-MPA reference sites. Harvest was estimated by fitting a size-structured population model to survey data.

Overall, harvest rates were effectively zero in MPAs but much higher in non-MPA sites. The authors state that this indicates successful adherence to MPA regulations, and possible displacement of fishing effort to reference sites. However, the authors highlight that some poaching was detected into a few MPA sites, showing the importance of assessing this quantity.

The authors conclude that this modelling approach could provide a tool to complement the long-term management of MPA networks, particularly given the difficulty of acquiring harvest rate data at the spatial scale of individual MPAs.

White et al. (2020) Analysis of fish population size distributions confirms cessation of fishing in marine protected areas. Conservation Letters DOI: 10.1111/conl.12775