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The model provides a basic estimate of the relative size of coral reef fisheries catch. This catch is determined as a function of estimated reef productivity and fishing effort. A minor modifier to this basic model makes allowance for no-take fishing areas (where catches are zero) with a small buffer of potential enhanced fisheries in adjacent waters (spillover). We do not account for variability in the economic or social value of these fisheries. This global data set reflects the world's coral reefs as a 500m grid, classified by a relative estimate of the annual fish harvest. Values are represented in decile blocks. The estimation of coral-reef associated fisheries involves 4 steps:
Estimate the pristine potential maximum sustainable yield on coral reefs – reflecting the potential sustainable production of fish on healthy reefs. This estimate was based on a review of numerous published estimates of fisheries yields or maximum sustainable yield per unit area world-wide. Estimate the realistic potential MSY on coral reefs, in light of current reef condition (degradation) reducing productivity. A proportional reduction based on the Reefs at Risk model of integrated threat, informed by other studies
Estimate catch based on the potential MSY, adjusted by nearby population and available fishing area, using a model adapted from previous field-based studies (reefs are recorded as reaching maximum fishing effort at population levels greater than 600 persons within reach of each square kilometre of reef. This catch layer was modified for strictly protected no-take zones. Catch values were reduced to zero (no catch) in the no-take zones while changing the potential catch in a surrounding 1km buffer was raised to the maximum value. |