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Habitat Equivalency Analysis (HEA) and Resource Equivalency Analysis (REA) each require the Natural Resource Damage Assessment (NRDA) practitioner to assess both the likely behavior of impacted systems or populations had there not been a pollution event (baseline) and the response of the impacted system/populations given the pollution event, response actions, and restoration. In the past several years, a general consensus regarding the approach and biological assumptions underlying HEA has arisen. While the details vary with the particulars of the spill, cooperative NRDA for Chalk Point, M/V Stuyvesant, Lake Barre, and other spills reveal an emerging consensus surrounding the application of HEA to specific components of oil spill assessment. The same progression and consensus has not been observed with respect to the biological assumptions underlying REA. Assessments conducted for the Chalk Point (NOAA et al. 2002a), the Lake Barre (Penn and Tomasi 2002), North Cape (Sperduto et al. 1999, 2003) the Stuyvesant (CDFG et al. 2004), the Anitra (NJDEP et al. 2004) and the New Carissa (MIV New Carissa 2006) oil spills have used REA frameworks that differ from one another. Further, the variation in REA frameworks alone has resulted in NRD assessments that would differ by millions of dollars, even if all assumptions related to initial injury levels, underlying biological parameters, and the functioning of restoration projects were identical. The purpose of this paper is to fuse the work of Penn and Tomasi (2002) Sperduto et al. (1999, 2003), NOAA et al. (2002a), CDFG et al. (2004) Zafonti and Hampton (2005) and others with basic ecological theory to refine and extend current practices resulting in a more standardized approach to REA. For spills in which chronic, long term exposure is not an issue, we apply basic ecological approaches that consider a species ability to respond to environmental perturbation based on (1) changes to the proportion of adults attempting to breed, (2) changes in productivity (defined as fledglings per nesting pair), and (3) changes to annual survival rates. We show that, these factors, when integrated with a simple set of population dynamic equations, provide NRDA practitioners a common, easily understood framework upon which they can assess damages and the necessary scale of potential restoration options.

As a result of oil spills endangered species may be killed. This paper discusses issues associated with scaling restoration projects that would compensate for mortality of an endangered species due to an oil spill. We illustrate our concerns using hypothetical data and a simple stochastic population dynamics model meant to (roughly) approximate Marbeled Murrelets (a federally-listed west- coast seabird) killed as result of a spill. The paper discusses the implications of possible outcomes with very long run implications (i.e. extinction), for which conservation biologists have generated various approaches for guiding management decisions in which discounting is not used. These are contrasted with the usual scaling approach, Resource Equivalency Analysis, which uses (expected) discounted bird years (EDBYs).