Dh. Monson et al., Long-term impacts of the Exxon Valdez oil spill on sea otters, assessed through age-dependent mortality patterns, P NAS US, 97(12), 2000, pp. 6562-6567
Citations number
48
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
We use age distributions of sea otters (Enhydra lutris) found dead on beach
es of western Prince William Sound, Alaska, between 1976 and 1998 in conjun
ction with time-varying demographic models to test for lingering effects fr
om the 1989 Exxon Valdez oil spill. Our results show that sea otters in thi
s area had decreased survival rates in the years following the spill and th
at the effects of the spill on annual survival increased rather than dissip
ated for older animals. Otters born after the 1989 spill were affected less
than those alive in March 1989, but do show continuing negative effects th
rough 1998. Population-wide effects of the spill appear to have slowly diss
ipated through time, due largely to the loss of cohorts alive during the sp
ill. Our results demonstrate that the difficult-to-detect long-term impacts
of environmental disasters may still be highly significant and can be rigo
rously analyzed by using a combination of population data, modeling techniq
ues, and statistical analyses.