Scientific considerations for designing marine reserves

Designing for Success

A successful design for a marine reserve or reserve network depends on clearly stated goals. One important goal for creating marine reserves is to protect or restore an ocean ecosystem, enabling it to provide ecosystem services such as seafood production, good water quality, coastal protection, and climate regulation on a sustainable basis. Other important goals for marine reserves are to maintain fishing lifestyles and incomes, provide recreational and cultural opportunities, and provide places for education and research.
The following are important considerations when designing marine reserves:
- Location: Where should a reserve be placed?
- Reserve size: How big should a marine reserve be?
- Network design: How many reserves and how close together should they be?
- Socioeconomics: How do people influence the planning and design of marine reserves?

Where Should a Reserve be Located?

Scientific considerations for locating marine reserves include:
- Different habitat types in the region
- Oceanographic features, such as linkages created by ocean currents
- Important places for species of interest, such as vulnerable spawning grounds
- Locations inhabited by rare or geographically restricted species
- Prior habitat damage and potential for recovery
- Vulnerability to natural and human impacts, including those from which marine reserves do not offer protection, such as pollution
- Location of human activities such as fishing, tourism, transportation, scientific research, and cultural resources
- Perceptions and preferences of local communities and policy makers
- Socio-economic impacts and opportunities provided by a reserve
Ocean ecosystems depend on connected habitats
Snapper life cycle
In the ocean, habitats are connected through movement of animals and plants and through exchange of nutrients. Most marine fishes and invertebrates use more than one habitat during their lives. Additionally, each habitat is home to a special group of animals and plants. When the goal of a marine reserve is to protect many species, it is essential for all habitats used by these species throughout their lives to be represented in reserves.

How Big Should a Reserve Be?

Home range size
Scientific studies show that even small marine reserves can have positive impacts on the abundance, biomass, body size, and biodiversity of animals and plants within their boundaries. However, a bigger marine reserve can protect more habitat types, more habitat area, bigger populations of animals, and a larger fraction of the total number of species in an ecosystem.
The level of protection that a marine reserve provides to a fish or invertebrate species depends partly on how far individuals move. If some individuals stay entirely inside the reserve, the species can receive a high level of protection. If individuals tend to travel outside the reserve, however, the species can receive only a lower level of protection. For these species, marine reserves can still protect significant sites for their food resources or critical parts of their life cycle.


Designing Networks of Marine Reserves


California network

How many reserves should there be?
Sometimes it is more economically sustainable to establish several smaller marine reserves instead of one big reserve in a particular area. In such cases, ecological benefits can be maximized by creating multiple reserves that are close enough to act as a network. Young and adults traveling out of one reserve may end up being protected in another reserve. Networks are most effective when each type of habitat is represented in multiple reserves, and when individual reserves are big enough and close enough to protect adults and young.
How close together should reserves be?
If a group of marine reserves is to function as a network, the reserves must be close enough to connect with each other through movement of animals. Marine species vary tremendously in how far they move. For many coastal species, the young, called larvae or propagules, move farther than adults. Consequently, a reserve network may be designed so that individual reserves are large enough to accommodate the movement of adults, while spacing among reserves accommodates the longer-distance movement patterns of young.
Young that travel short distances may stay inside the reserve where they were born. Other young are likely to end up outside. Reserves that are more closely spaced can be ecologically connected and protect a greater fraction of species through movement patterns of young.


People and Marine Reserve Design

The socioeconomic costs and benefits of marine reserves influence their planning, design, and eventual outcomes. Broader policy issues, such as the relationship between marine reserves and other tools for ocean governance, also play an important role. For example, reserves alone cannot protect ocean biodiversity or fisheries if unsustainable fishing occurs in waters outside marine reserves.  Increased attention to the human dimensions of marine reserves and ocean governance will be necessary to ensure effective management over the long term.
How do people influence the planning and design of marine reserves?
As people are involved in marine reserve planning, many different viewpoints can be accommodated while still achieving conservation and management goals. Both scientific and socioeconomic priorities are important in the design and planning of marine reserves. The following are important human factors to consider:
- No-take Recreation: Marine reserves can be ideal for non-consumptive recreational activities, such as whale-watching, sightseeing, scuba diving, and snorkeling. Care must be taken to ensure that recreational activities do not damage sensitive plants, animals, and habitats.
- Existing Patterns of Human Activities: Maps showing where human activities-such as fishing, aquaculture, and energy production-occur in the ocean can be used to reduce the potential negative effects of marine reserves on people's lives and the economy.
- Cultural Values: Sometimes marine reserves can protect areas of historical, cultural, or spiritual significance. Historians and cultural experts should be consulted to determine how marine reserves could help achieve this goal.
- Compliance and Enforcement: If users have participated in the decisions that lead to restrictions they will be more aware of the objectives, boundaries, and use restrictions. They are then more likely to cooperate and encourage other users to comply. This compliance is essential for successful conservation. Effective enforcement, for example by government wardens or members of the community, is also essential to ensure the compliance of all users. Compliance is likely to be most successful if policy mechanisms ensure integration across different levels of government and different user groups. 
- Monitoring: Monitoring ecological, social, and economic changes associated with marine reserves is critical to determine if management goals are being achieved. Scientists and managers can collaborate to plan and implement monitoring programs.
- Long-term Support: Ecological benefits that build-up over decades can be wiped out in a year or two if a marine reserve is not maintained and enforced. Long-term arrangements for funding, training, management and other support is essential.
Economic Impacts
The economic impacts of marine reserves are complex because they differ by site and business sector. Because marine reserves protect valuable ecosystem services that otherwise may be lost, a well-designed and enforced network of marine reserves could generate an overall long-term economic benefit.
Alternative income opportunities can result from increases in local tourism. Some marine reserves draw sightseers, kayakers, scuba divers, and other tourists, who add money to the local economy. For example, a study showed that most dive operators in 30 Latin American and Caribbean countries took their clients to marine protected areas. These divers paid more than $1 billion annually in user fees. Of course, care must be taken to ensure that recreational activities do not adversely impact the reserve.

Case Studies of Reserve Planning Processes

An analysis of marine reserve planning demonstrates that clear goals, effective use of scientific advice, and participation of multiple groups affect reserve success. The following Science of Marine Reserve case studies are examples of different ways in which science has provided information for people involved with creating marine reserves in diverse social and economic situations around the world.


Visit the PISCO Website


Visit the website of the Partnership for Interdisciplinary Studies of Coastal Oceans to learn more about the Science of Marine Reserves.  

There you can download our booklets, video series, and high-resolution figures.

Subscribe to our newsletter