Resource Equivalency Analysis (“REA”) is often used to “right-size” (scale) or calibrate compensatory restoration projects implemented as part of Natural Resource Damage Assessments (“NRDAs”) conducted pursuant to the Oil Pollution Act of 1990 (“OPA”). The basic premise underlying REA is that, if a spill results in the loss of individual members of a population, the public can be compensated via a restoration project which creates individuals that otherwise would not exist. This is because the ecological services provided by a population are proportional to the number of individuals in the population. For example, one could compensate the public for spill-related mortality among shrimp by creating wetland terraces which, the literature suggests, would increase the number of shrimp in the population. REA answers the question, “How many wetland terraces need to be created?”
Implicit in the REA construct is the dynamic nature of the population projections. Even with density dependence, population levels fluctuate according to both biological and anthropogenic factors that combine to influence survival, reproductive and growth rates. Thus, if NRDA practitioners are to reliably identify compensatory restoration requirements using REA, it is necessary to: characterize baseline demographic rates; develop a model that uses those baseline demographic rates to project future population levels; and identify the mechanisms that cause post-spill rates to change relative to baseline expectations.
One factor that can cause post-spill demographic rates to vary is a spill-related change in human behavior. For example, if a spill-related fishing closure results in the cancelation of 15,000 recreational shrimping trips, shrimp mortality due to fishing will decrease.
In this paper we use prior OPA NRDA cases to: review the historical treatment of spill-related closures in REA models used by both DOI/USFWS and NOAA; and illustrate that the REA practitioners’ approach to these spill-related changes in human behavior can (and should) change the NRDA liability construct, particularly with respect to species which are commercially and recreationally harvested.