Marine Planning
Practical Approaches to Ocean and Coastal Decision-Making
www.marineplanning.org

Set Goals

There is no specific formula to determine how much habitat or how many populations are required to conserve or manage any particular target. But there is some common sense advice:

coastal conditions map

Maps illustrate number of priority areas chosen in Marxan when goals are cut in half. Click on image to view map of original "Best Solution."

Case Study: Carolinian Ecoregion

In the Carolinian ecoregion, expert advice was sought on setting goals for all the targets. Most goals were set at 30 percent of their current distributions or higher, because many of the targets have been substantially reduced in abundance or degraded in terms of function or quality.

For the reddish egret, a 100 percent goal was set, because there is only one recorded egret rookery in the ecoregion.

Restoration goals were also set, because the current distribution of some targets was already insufficient for their continued persistence. For shellfish ecosystems, goals were set at 30 percent of their potential distributions (i.e., classified as supporting shellfish by EPA).

More importantly, goals were varied to explore how different goals affected the overall results in terms of the numbers and locations of priority sites. The two figures illustrate the differences in number of priority areas chosen in Marxan when goals are cut in half. In this case the relationship is linear (~50% fewer sites are chosen), but that is not always the case.

 

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