Debate continues around the efficacy of marine protected areas (MPAs) for managing and maintaining exploited fish stocks.

Fish are generally larger in MPAs, and a recent metanalysis showed that larger fish produce disproportionately (hyperallometrically) more offspring than smaller fish; however, models of fish populations do not typically take this difference in production into account.

This study explored the consequences of hyperallometric reproduction for a range of species for population replenishment and the productivity of exploited species.

The results show that the reproductive contribution of fish inside MPAs has been systematically underestimated and that fisheries yields can be enhanced by the establishment of reservoirs of larger, highly fecund fish.

The authors state that including the disproportionate reproduction of larger fish into models of fish replenishment increases the benefits of MPAs dramatically. It is highlighted that in terms of egg production, a single hectare of MPA is equivalent to 3-225 ha of unprotected area on average, depending on the fish species being considered.

It is concluded that MPAs represent an essential tool for protecting larger fish, and a more accurate accounting of the value of MPAs will increase support for their use by a wide variety of stakeholders.

Marshall et al. (2019) Underestimating the benefits of marine protected areas for the replenishment of fished populations. Frontiers in Ecology and the Environment doi:10.1002/fee.2075.