Tuesday, December 4, 2007

Science Guidelines for MPAs

The science guidance provided to the RSGs is a subset of what has been published on the subject. There is consensus among marine ecologists that MPAs are not a panacea that can effectively achieve results in all situations.

Some of the areas of disagreement that have kept out of the MLPA process include:
  • The interaction of fisheries management practices with MPAs
  • The few and large versus small and numerous MPA debate
  • Diffuse biodiversity goals versus measurable fisheries objectives
Here are several excellent journal publications that could serve as guidance to RSGs if listened to:

After the Central Coast MLPA process, Hilborn, Walters et al were commissioned by the Cal Fisheries Coalition to do a peer review. This critique is the reason why the scoring methodology is being backed up by running the RSG proposals through two or three models.

The SAT is currently trying to decide which "models" to use to evaluate the RSG proposals. It appears that the Botsford model and Walters model will win out. These models are spreadsheets into which they plug certain local data, though we are unclear about these independent variables.

Botsford's Principles for Design of Marine Reserves include:
  • Adding reserves is equivalent to increasing the size limits in fishing
  • Adding reserves is equivalent to limiting fishing
  • MPAs preserve biodiversity best when inhabitants don't travel far (like abalone and rockfish)
  • If the goal is to protect more active species (like halibut, sharks, deeper water rockfish) the MPA must occupy a long stretch of coast
  • Very little is known about the relationship between variables or behavior of different species. Type 1 and 2 errors will be high.
Dr. Carr writes about when MPAs are and are not appropriate. This is a very readable elaboration of the potential objectives met by MPAs and the uncertainties. He calls for an "increased need for accountability and the explicit statement of performance-oriented conservation goals. Consequently, there is an immediate need to set realistic MPA objectives, expressed as well defined, tractable, and measurable targets."

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