By Loren Bell, Mongabay-Indonesia contributor
10 February 2014
(mongabay.com) – Protecting large, isolated areas of no-take zones for over 10 years with strong enforcement is the key to effective Marine Protected Areas (MPAs), according to a letter published this week in Nature. However, 59% of all MPAs meet less than three of the five criteria, making them protected in name only.
The authors look at 964 sites in 87 MPAs worldwide and identify which factors determine a successful MPA. They write that the key ingredients are:
"(1) degree of fishing permitted…; (2) level of enforcement; (3) MPA age; (4) MPA size; and (5) presence of continuous habitat allowing unconstrained movement of fish."
An MPA that fails to meet at least three of these criteria is statistically no different from fished areas, while each additional factor above three increases its conservation value exponentially.
Although the authors do find that, "across all 87 MPAs investigated, species richness of large fishes was 36% greater inside MPAs compared to fished areas, biomass of large fishes was 35% greater, and sharks 101% greater," they continue to note that, "for species richness of all fishes and the other four bio- mass metrics investigated, no significant difference was found ."
The poor overall performance of MPAs worldwide is likely due the significant number of ineffective protected areas: only four of the 87 MPAs studied meet all five key criteria. Using those "effective" Areas as a standard, the authors find that in the other MPAs, "fish biomass was greatly reduced overall, with 63% of all fish biomass, 80% of large fish biomass, 93% of sharks, 84% of groupers and 85% of jacks apparently removed from reefs by fishing."
MPAs have proliferated in recent years as countries rush to meet protection targets. In 1970, there were 118 MPAs in 27 nations. By 1994, over 1,300 MPAs existed worldwide. In 2010, nearly 5,900 MPAs had been established. However, as impressive as those numbers sound, protected areas account for less than 2% of the world's oceans, and without effective management, do little to assist in recovery of diversity or biomass. [more]
ABSTRACT: In line with global targets agreed under the Convention on Biological Diversity, the number of marine protected areas (MPAs) is increasing rapidly, yet socio-economic benefits generated by MPAs remain difficult to predict and under debate1, 2. MPAs often fail to reach their full potential as a consequence of factors such as illegal harvesting, regulations that legally allow detrimental harvesting, or emigration of animals outside boundaries because of continuous habitat or inadequate size of reserve3, 4, 5. Here we show that the conservation benefits of 87 MPAs investigated worldwide increase exponentially with the accumulation of five key features: no take, well enforced, old (>10 years), large (>100 km2), and isolated by deep water or sand. Using effective MPAs with four or five key features as an unfished standard, comparisons of underwater survey data from effective MPAs with predictions based on survey data from fished coasts indicate that total fish biomass has declined about two-thirds from historical baselines as a result of fishing. Effective MPAs also had twice as many large (>250 mm total length) fish species per transect, five times more large fish biomass, and fourteen times more shark biomass than fished areas. Most (59%) of the MPAs studied had only one or two key features and were not ecologically distinguishable from fished sites. Our results show that global conservation targets based on area alone will not optimize protection of marine biodiversity. More emphasis is needed on better MPA design, durable management and compliance to ensure that MPAs achieve their desired conservation value.