Marine Reserves

What are Marine Reserves?

Marine reserves

St. Kilda, Scottish Natural Heritage

Marine reserves are defined as ocean areas that are fully and permanently protected from activities that remove animals and plants or alter habitats, except as needed for scientific monitoring. Examples of prohibited activities in marine reserves are fishing, aquaculture, dredging, and mining. In contrast, activities such as swimming, boating, and scuba diving are usually allowed. Marine reserves differ from other kinds of MPAs which exclude only some extractive activities or which provide seasonal or short-term protection.

Because marine reserves protect habitats and the diversity of animals and plants that live in those habitats, they can help produce different outcomes from other management tools. Scientific evidence shows that marine reserves usually boost the abundance, diversity, and size of marine species living within their borders. Additionally, marine reserves may also be able to replenish fished areas when young and adult fish move out of the reserve.

Although marine reserves can be an effective tool, reserves alone cannot address problems such as pollution, climate change, or overfishing. Other management strategies are needed along with the creation of marine reserves. Additionally, as with any form of management, a marine reserve is only effective if its protection is enforced.

Networks of marine reserves

New Caledonia MPA, Dan Laffoley of Natural England

New Caledonia, World Heritage Site
- Dan Laffoley, Natural England

In many places, a single marine reserve that is large enough to protect all habitats may be impractical because of geography or the possibility of initial socioeconomic impacts. For example, a large reserve might cause fishermen to have to travel greater distances to fishing sites, incurring greater costs to them. Establishing an ecological network of several small- or medium-sized marine reserves in a region, rather than one or two large reserves, can be a viable alternative I some cases to meet established goals while reducing the negative social or economic impacts of a single large reserve.

A major socioeconomic benefit of a marine reserve network is that fishing and other human activities can occur between the reserves instead of being excluded from one large area. Young fishes and invertebrates generally are less vulnerable to fishing due to their small size, so at least a portion may disperse safely among the reserves, providing a source of young for reserves and fished areas outside. Reserve networks can also provide insurance because a catastrophe that harms populations and habitats in one marine reserve (such as a hurricane or oil spill) may not affect other reserves.

Marine reserve design

As scientists learn more about marine ecosystems and human interactions within the ocean, analyses suggest that reserves work best when ecological, social and economic considerations are all factored into the design plans. In general, creating reserves involves a series of tradeoffs that must be balanced to meet the goals.

Scientific information can inform where a reserve should be located, how large a reserve should be and for networks of reserves, how many are needed and how close together they should be spaced. Additionally, increased attention to the human dimensions of marine reserves, including the social and economic factors that enhance the success of reserves, will be necessary to ensure effective management over the long term.