Other studies were conducted by scientists supported by Exxon (subsequently Exxon Mobil). These

different groups of scientists often collected different types of data and interpreted data somewhat differently; these Gefitinib manufacturer varied approaches, which often yielded disparate findings, enhanced scientific rigor, even if it led to less-certain conclusions. This paper was motivated by a series of recent reports asserting, definitively, that sea otters in one area of WPWS that was heavily oiled continue to suffer, individually and demographically, from residual effects of the 1989 spill (Bodkin et al., 2011, Bodkin et al., 2012, Monson et al., 2011 and Miles et al., 2012). Here we critically evaluate these and other previous studies that collectively have argued that selleck chemical effects of the spill persisted for more than two decades, thus providing the basis for keeping sea otters on the short list of species that

have not yet recovered from EVOS (Exxon Valdez Oil Spill Trustee Council, 2009). Our intent is not to present a comprehensive review of the impacts of the spill on sea otters, but rather to focus on results that have been interpreted as evidence of effects continuing to the present. We do not discredit any of the investigators who reached these conclusions; we simply aim to offer an alternate interpretation of data related to long-term demographic consequences. Acute effects of the spill on sea otters were well documented, and the vulnerability of this species to oil contamination confirmed (Bayha and Kormendy, 1990 and Lipscomb et al., 1994). Whereas estimates of direct, spill-related mortality varied widely with varying methodological procedures and assumptions (Garrott et al., 1993, DeGange et al., 1994, Garshelis, 1997 and Garshelis and Estes, 1997), there was no doubt that a large proportion of otters in WPWS

died. With time, and the continued weathering of the oil residues, it was generally presumed that sea otters would gradually rebound to baseline conditions. In an introductory chapter to a book summarizing a symposium on effects of EVOS, held 4 years Thiamine-diphosphate kinase after the spill, Spies et al. (1996, p. 11) wrote: “These results do not preclude ongoing toxic effects in highly sensitive species in some areas, but they do support a conclusion that direct effects of the oil in the intertidal zone [where the residual oil settled] were largely over by 1991, when major cleanup activities ceased.” Indications that this was not the case for sea otters began to emerge by the mid-1990s, stimulating further studies of recovery of this species (Holland-Bartels et al., 1996).