Wednesday, March 30, 2011
FOR IMMEDIATE RELEASE:
Tanya Gabettie Grady
PCCS Co-authors Paper on Potential Impacts of the Gulf Incident
(Provincetown, MA) - The paper, Underestimating the Damage: Interpreting Cetacean Carcass Recoveries in the Context of the Deepwater Horizon/BP Incident, is published in Conservation Letters.
The paper is authored by: Rob Williams, Shane Gero, Lars Bejder, John Calambokidis, Scott Kraus, David Lusseau, Andrew Read and Jooke Robbins of the Provincetown Center for Coastal Studies.
Abstract: Evaluating impacts of human activities on marine ecosystems is difficult when effects occur out of plain sight. Oil spill severity is often measured by the number of marine birds and mammals killed, but only a small fraction of carcasses are recovered. The Deepwater Horizon/BP oil spill in the Gulf of Mexico was the largest in US history, but some reports implied modest environmental impacts, in part because of a relatively low number (101) of observed marine mammal mortalities. We estimate historical carcass detection rates for 14 cetacean species in the northern Gulf of Mexico that have estimates of abundance, survival rates and stranding records. This preliminary analysis suggests that carcasses are recovered, on average, from only 2% (range: 0-6.2%) of cetacean deaths. Thus, the true death toll could be 50 times the number of carcasses recovered, given no additional information. We discuss caveats to this estimate, but present it as a counterpoint to illustrate the magnitude of misrepresentation implicit in presenting observed carcass counts without similar qualification. We urge methodological development to develop appropriate multipliers. Analytical methods are required to account explicitly for low probability of carcass recovery from cryptic mortality events (e.g., oil spills, ship strikes, and acoustic trauma).
Click here to read the Conservation Letters release.