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Expanding marine protected areas by 5% could boost fish catches by 20% – but there's a catch

4 November 2020

The policy limitations of mathematical models

Expanding marine protected areas

A review in The ConversationÌý²ú²â Dr Peter Jones (Ïã¸ÛÁùºÏ²Ê Geography) and Professor Ric Stafford (Bournemouth University) discusses a recent paper, A global network of marine protected areas for food, in the Proceedings of the National Academy of Sciences (PNAS).

The PNAS paper claims that strategically expanding the existing global network of Marine Protected Areas (MPAs) by just 5% can improve future catch by at least 20%. The review considers some of the challenges of applying such a policy, concluding that the reality is more complicated than the models assume.

To achieve such a goal would, first, require the proposed MPAs to be in inshore productive seas that are actually fished. Most of the currently designated MPAs are ‘low hanging fruit’ in remote offshore ocean areas used by few fishers (Jones and De Santos, 2016).

The fishing industry will also vigorously object since they are not generally convinced of the spillover benefits of MPAs. As a consequence, while 36% of the marine waters around the UK are covered by MPAs, only 0.0024% have a complete ban on all fishing (i.e. ‘Highly Protected MPAs’).

Increasing the number & size of Highly Protected MPAs from such small sites to 5% of the UK’s sea area (excluding overseas territories) would represent more than a 2,000-fold increase, to which the National Federation of Fishermen's Organisations would no doubt object, further undermining political will to conserve fisheries and marine ecosystems through MPA designations.

The paper is also based on mathematical fisheries models of MPA designations, neglecting the potential to collaborate in designing such networks with fishers, many of whom remain sceptical of both the potential for spillover benefits and the validity of fisheries models.

These challenges need to be addressed, both to gain the political will to designate MPAs in face of fishers’ objections and to develop evidence for their spillover benefits. More fishers might then be convinced of the vital role of MPAS in boosting catches, as well as keeping people fed and restoring ocean ecosystems.


See

  • Reniel B. Cabral, Darcy Bradley, Juan Mayorga,  Whitney Goodell, Alan M. Friedlander, Enric Sala, Christopher Costello, and Steven D. Gain. A global network of marine protected areas for food. PNAS first published October 26, 2020; 
  • Peter JS Jones and Elizabeth M. De Santo  The Conversation, September 1, 2016