islas medas reserva marina

What’s the function of a marine reserve?

The fact human beings benefit from the sea in many different ways is undeniable. Despite this, it seems we have forgotten this since our actions are slowly degrading the oceans. It is for this reason that have emerged different management tools, such as marine reserves. But, what are they and what is their function?


Marine reserves are areas protected by fishery legislation with the aim of regenerating fishing resources and traditional artisanal fisheries in a particular area. Thus, a marine reserve is an area where fishing is forbidden.

This concept might easily be confused with a marine protected area (MPA). According to the WWF, they refer to any marine and coastal area defined by legislation to protect their ecosystems, ecological processes, habitats and species that can contribute to the restoration of social, economic and cultural resources.

In fact, although they are not comparable concepts, they largely overlap.

mediterraneo reserva marina
The concepts marine reserve and marine protected area are not equal, but similar (Picture: Enric Sala).


Marine reserves are not homogeneous from the point of view of the uses that are allowed in them.

Most reserves have an area in which any use is allowed, known as integral reserve. In these areas there is a lack of fishing.

In the rest of the reserve, however, artisanal fishing, diving, anchoring, recreational fishing… are regulated. Artisanal fishing is allowed to usual professionals in the area. Diving, on the other hand, has to be respectful to the environment. Thus, the maximum number of fishing boats and diving quotas are established.

buceo recreativo, reservas marinas
Diving is regulated in marine reserves by establishing the maximum number of divers (Foto: Maria José Ochoa Muñoz, Creative Commons).

Do you fish (recreational fishing) in marine reserves? Here you can know the impact of this activity.


The creation of marine reserves generates a set of benefits at different levels.

The general public is often unaware of the marine environment and life for the simple fact that are hidden underwater. Thus, marine reserves are a tool for dissemination of natural heritage with great potential.

Another benefit is the fact they are good places to develop scientific research: are usually monitored, allow a better understanding of the ecosystem, allow to have long-term data from the same area and there is a control of its evolution over time.

They also permit the development of different economic activities, although this should not be the main goal. Activities such as diving and snorkeling are common in these areas, and increases the number of visitors in the vicinity of the reserve.

Although the above benefits are important, the reserve effect is the main objective sought when creating a marine reserve.


The reserve effect refers to the conservation of the ecosystem’s diversity and the conservation of ecosystem services.

efecto reserva marina
The reserve effect is the main goal sought when creating a marine reserve (Picture: Ocean Conservancy).

Among its benefits, there are:

  • Reduction of mortality caused by fishing or derived from habitat destruction.
  • Increase of the size and abundance of populations (rebuilding).
  • Increase of the size (and age) of target species and density of breeding individuals.
  • Increase of the reproductive capacity of populations: Being larger, they have a higher reproductive capacity. Moreover, as more individuals are present, it increases the number of lays and the production of eggs and larvae.
  • The natural characteristics of habitats and marine communities recover as all trophic levels and trophic cascades recover.
  • Species of flora and fauna that are not of commercial interest are recovered (marine mammals, sea turtles, sea grasses…).

So, they help to reduce the negative effects of fishing both at the ecosystem level and at the level of marine species.

Two clear examples of the reserve effect on species are the grouper (Epinephelus marginatus) and lobsters (Elephas palinuris).

mero Epinephelus marginatus
The grouper (Epinephelus marginatus) is a clear example of the benefits of marine reserves on marine biodiversity (Picture: Parent Géry, Creative Commons).

Its benefits extend beyond the marine reserve when the number of individuals within the reserve reaches its maximum capacity and then they are out of range. Therefore, it increases the density of individuals outside and ecosystems benefit from it. This process is known as spillover.

Not only do ecosystems benefit, but so do the fishermen since they have access to them.


We should note that marine reserves can only work if they are large enough, they are close enough to each other, they are representative of different habitats and marine ecosystems, are sufficient in number and they are actively protected.

In other words, what is really useful for conservation of the marine environment is the creation of a network of reserves, ie, a set of areas that meet the above five requirements.


Although the rules will depend on the specific marine reserve to which we are, we can take the following points as generalities. In a marine reserve it is prohibited:

  1. Perform discharges.
  2. Anchoring on seagrass beds.
  3. Capture or collect protected species. In case of accidental capture, is has to be returned (causing minimal damage).
  4. Feeding wildlife.
  5. Any activity or behaviour that might cause annoyance or harm to whales or sea turtles.


  • Brito, T., González, S. y Miota, F. 2012. Reservas Marinas de Canarias. Dirección General de Recursos Pesqueros y Acuicultura. Secretaría General de Pesca. Ministerio de Agricultura, Alimentación y Medio Ambiente. 24 pp.
  • López-Ornat, A; Atauri, JA; Ruiz, C; Múgica, M. 2014. Beneficios sociales y ambientales de las reservas marinas de interés pesquero. Fundación Fernando González Bernáldez.
  • Ministerio de Agricultura, Alimentación y Medio Ambiente. Guía de buenas prácticas en las zonas especiales de conservación de ámbito marino de Canarias
  • Ministerio de Agricultura, Alimentación y Medio Ambiente. Red de reservas marinas. Más de 25 años protegiendo nuestros mares.
  • Notes of the Master in Oceanography and Marine environment managment
  • The Wildlife Trusts: Marine Protected Areas



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