Marine Protected Areas deemed largely ineffective
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.
There is no single factor that determines the success of an MPA, however, size and isolation appear to be most favorable for large species such as sharks and groupers. In the absence of size, the additive effect the other four factors—effective management, enforced no-take policies, long-term establishment, and inclusion of deep-water areas surrounding reefs—can be sufficient to compensate.
Read more at ENN affiliate Mongabay.
MPA map via the Marine Conservation Institute.