How Marine Protected Areas Restore Fisheries

By wildgirl -

Fish stocks are dwindling the world over. Dr Anjani Ganase discusses how well-managed Marine Protected Areas help to protect nurseries.

 

All fisheries are in decline; trends in the Caribbean mirror the global statistics.  There is emerging a consensus on strategies for improving fish stocks by ensuring conservation and protection of marine ecosystems.  The solution is a holistic approach based on the establishment of “no take” marine reserves, also known as fully protected Marine Protected Areas (MPAs) where there is no fishing, recreational or commercial, allowed. We may be surprised by the solution, as many consider closing areas to fishing would reduce the fishing grounds available to the fisherfolk thereby limiting the catch. Yet, the opposite proved true, the development of well-designed and fully protected MPAs would improve overall fish catches in surrounding areas even more effectively than a fisheries management plan. So how is this possible?

 

 

 
Large as they are, wahoo brought in to the Charlotteville depot are smaller than they were 20 years ago. Photo Pat Ganase

 

Fisheries management plans focus on the species of fish instead of accounting for the conservation of the ecosystems the fish utilise which is the aim in MPAs.  Fully protected MPAs have shown to be much more successful compared to a fisheries management plan. There are numerous additional benefits of the MPA, where the conservation of the habitats leads to restoring the marine life and biodiversity at all levels, thus enhancing its ecological resilience to other disturbances. Furthermore, they do more than simply protect the organisms, they permit important ecological and physical processes such as coral reef spawning aggregations and water purification processes.

 

“MPAs conserve biodiversity, enhance resilience, enhance fisheries, and act as an insurance policy if other types of fisheries management do not work. They protect and restore endangered species and ecosystems. They are sites for education and research. They can attract tourists and provide alternative livelihoods for communities.” - Ellen Pikitch, conservation scientist

 

 

 
Diving in the northeast Tobago Reserve, where one of the world’s largest brain corals is located, could be a source of greater revenue than fishing. Photo courtesy the Maritime Ocean Collection, 

 

How do fully protected MPAs bolster the productivity of surrounding fisheries?

 

Firstly, MPAs serve as a refuge for target fish species where this refuge allows a portion of the fish stocks to have a chance to grow bigger and to the reproductive age. Reproduction increase results in the spillover of offspring and fish larvae to inhabit neighbouring marine habitats. Scientists have observed that the size of commercial species present within the MPA to be 6 – 7 times large than the sizes in the adjacent areas. Larger fish can produce significantly higher numbers of offspring per spawning event compared to smaller adults without the MPA refuge, adding to the fish stocks. As the numbers of the fish increase, so will the increase in the number of these large fish that exit the MPA. In some areas, such an increase was able to restore commercial fishing activities that are less viable over time without proper management. More specifically, the Catch Per Unit Effort increases in areas found adjacent to marine protected areas.

 

How do coastal economies benefit?

 

The total value of protecting MPAs include the benefit of neighbouring fisheries but there are additional benefits with respect to the other activities surrounding the MPA such as monitoring, research and management activities and the jobs needed to support these activities. Apart from the diversification of income, there are the added indirect benefits of the MPAs which can include processes such as coastal protection.  It was estimated that for every $1 invested into the MPA, there is an average return of $20 in investment for fully functioning MPAs (Cooney et al 2019). With respect to the time for the return on investment, it may be as short as five years, but more typical to see returns ten years after the establishment.

 

Apart from full protection, the success of the MPA is based on its design, geographic location and size. The placement of the MPA should be in areas that are productive and biodiverse ecosystems, such as coral reefs or rocky areas or seamounts that support marine nurseries and feeding. The MPA should be well connected to other marine habitats through ocean currents so that spillover fish and other marine larvae can reseed neighbouring reef sites. With respect to size, larger is better in order to cater for fish species of different home ranges - areas within which they do their daily activities. Another key element to the success of an MPA is that it should be buffered by deep ocean, sand or natural coastal areas as much as possible to avoid the uncontrollable influences of pollution and coastal development. Finally, while MPAs provide significant benefits to marine conservation it is not the solution for everything, as they do not protect against invasive species, pollution or climate change. However, the stability of the MPA will allow for faster recovery after disturbances.

 

Typically, it may take at least ten years before the benefits of the MPA is realized, although in areas of higher exploitation, improvements in the fish stock numbers tend to be noticeable early on. Within this time, the most significant challenge is recognizing the cost of those impacted by the transition, which will mainly be the fisherfolk and those dependent on fish supply. Solutions to bridge the gap include shifting to work in non-extractive fields such as tourism – boating and diving or by arranging for exclusive rights of the other areas around the MPA to fisherfolk, which will only work if there is a fisheries management plan that is enforced. Of course, the process of MPA design and management requires continued engagement with all stakeholders and resources for education, along with monitoring and enforcement, to ensure success. 

 

The proposed North-East Tobago MPA covers an estimated 59,280 ha, extending along the entire coastal strip from Roxborough on the north-east coast, around the coast to Parlatuvier on the north-west coast and extending seawards for 6 nautical miles (11.1 km). If we are true to the intentions of the UNESCO Man and the Biosphere accreditation, do we dare to imagine the beauty and benefit of executing this bold and courageous plan?

 

 

References

 

Christie, M.R., B.N. Tissot, M.A. Albins, J.P. Beets, Y. Jia, D.M. Ortiz, S.E. Thompson, and M.A. Hixon. 2010. Larval connectivity in an effective network of marine protected areas. PLoS ONE 5(12):e15715. doi:10.1371/journal.pone.0015715

 

Cooney, M., Goldstein, M., Shaprio, E. (2019) How Marine Protected Areas Help Fisheries and Ocean Ecosystems, Center for American Progress.

 

Halpern, B.S. 2003. The impact of marine reserves: do reserves work and does reserve size matter? Ecol. App.13(1) Supplement S117-S137.

 

Pikitch Ellen, “A Primer on Marine Protected Areas: Background for the 10x20 Conference” (Ocean Sanctuary Alliance, 2016), available at https://www.sprep.org/attach- ments/VirLib/Regional/mpa-primer2016.pdf.

 


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