Seal study 
debunked by scientists

09/08/2011

Independent scientists and scholars are concerned that the latest Point Reyes National Seashore study linking oyster cultivation to seal displacement in Drakes Estero relies on insufficient and unsupported data, and ignores one key event involving an extraordinarily aggressive elephant seal in 2003. 

Their reviews, which come days before the release of a draft environmental impact statement (EIS) that will greatly influence the fate of oystering in the estero, were invoked last week by Senator Dianne Feinstein as she urged Interior Secretary Ken Salazar to halt the year-long, million-dollar EIS process until federal scientists at the Marine Mammal Commission (MMC) vet the study. 

“The [draft EIS] must incorporate the findings of a review of the Park Service’s scientific work when it is in question especially given their history of misrepresenting science,” Feinstein wrote on September 2. “Not incorporating the Marine Mammal Commission’s report would threaten the validity of the environmental review.” 

The study, “Evidence for Long-Term Spatial Displacement of Breeding and Pupping Harbour Seals by Shellfish Aquaculture Over Three Decades,” was authored by Dr. Ben Becker, Dr. Sarah Allen and David Press and published in April. It concludes that 30 years of data demonstrate that high oyster activity has led to a seven percent spatial displacement of pups out of the estero. 

A related study was published in 2009 by the same individuals, and was highly criticized by scientists with the National Academy of Sciences and the MMC, which has been evaluating Point Reyes National Seashore data on harbor seals in Drakes Estero for over a year.

Dr. John Harwood of the University of St. Andrews, in Scotland, who was commissioned by the MMC to review the study, alleges that the correlation between oystering and seal displacement is weak at best. 

Other statisticians at Stanford and the University of California, Davis, who accepted requests to do the same—on condition of anonymity—from local stakeholders Dr. Corey Goodman and Marin County Supervisor Steve Kinsey, found similar results. 

Inverness-based research consultant, Dr. Dominique Richard, who was commissioned by local environmentalist Gordon Bennett, submitted a two-paged review that supported the study’s findings. 

Harwood and Goodman, supported by faculty at Stanford and Davis, contend that a single rogue elephant seal that killed dozens and displaced hundreds of harbor seals from Double Point, a nearby beach, into Drakes Estero in 2003 was likely the cause of temporary increases in seal counts in that and the subsequent year. The authors themselves noted the disturbance. Many of the displaced seals likely remained in the estero until 2005, when they returned to coastal beaches and more readily available food.

Oddly, contrary to its title, the study contains data from 1982 and 1983 but none from any other years prior to 1997, during which time critical oyster farm management changes were made. When asked in 2007 by the Inspector General for all data pre-dating 1996, then-Pacific West Regional Director Jon Jarvis wrote that they did not exist.  

Goodman, who last week submitted a 143-page critique of the study to MMC Director Tim Ragen, said the inclusion of data from these years—which he termed “cherry-picking”—served to artificially enhance the correlation between oyster activity and seal displacement. 

When the figures from 1982 and 1983 are removed from the analysis, and the impact from the rogue elephant seal is adjusted for, all correlation between oyster activity and seal displacement dissolves. 

UC Cooperative Extension Director David Lewis, who is trained in statistics and was asked by Kinsey to independently review the study, verified the findings by Harwood and Goodman. “The Becker et al study’s data set is too thin to reach its robust conclusions,” Lewis said. 

Goodman also alleges that the study’s principle map differs from those previously issued by the park service, and that it contains blatant errors. For instance, one area that suggests seals haul out on two large oyster beds was refuted by Allen herself when she explained to the MMC in February of 2010 that the area in question was too shallow and full of eelgrass for seals to inhabit. 

According to the reviews, which were submitted to Ragen and distributed to stakeholders last Tuesday, the study also misleadingly lumps annual oyster harvest rates into either “high” or “low” years rather than using specific counts. Those numbers are available from current and past oyster management and from the California Department of Public Health. By generalizing harvest counts, the authors artificially enhance the correlation between harvest and seal displacement. 

The study’s publication in the British online journal Aquatic Conservation: Marine and Freshwater Ecosystems was not publicized by the park service, but rather first announced on April 6, in a letter to the West Marin Citizen by the executive director of the Environmental Action Committee, Amy Trainer. 

Trainer’s letter came two weeks after the Interior Department released a report that found that park service personnel—including all three authors of the study—had violated the NPS Code of Scientific and Scholarly Conduct and that Becker, Allen and Press had shown a “willingness to allow subjective beliefs and values to guide scientific conclusions.” 

It is unclear why the study was not published in Marine Mammal Science, the American journal in which its 2009 predecessor was published.

Goodman said that Ragen had planned to convene a meeting with MMC scientists, park service officials and stakeholders, last week but that park service officials had refused to discuss the study or the reviews. Superintendent Cicely Muldoon was not available for comment. 

While Ragen acknowledged the urgency of such a meeting, he said it could take time. “The idea is not to get it out quickly,” he said, “but to get it out right.” 

Since the discovery last year of photographs that discredited all previous claims that oystering has caused seal disturbances in the estero, no new evidence had been brought forth proving otherwise. If the study is recalled, the legitimacy of the environmental impact statement, which is expected to hinge on its findings, could be compromised.

Proponents for the wilderness restoration of the estero, however, argue that the potential for the oyster operation to harm to seals and other marine life is grounds enough to deny an extension of its lease, which ends in November of 2012.

Speaking for the park service, Outreach Coordinator Melanie Gunn said her agency is “committed to completing the EIS process on time,” and that it would be glad to incorporate MMC’s findings into the final EIS when it is released—likely sometime next spring. 

That leaves plenty of time for the public to read, “Evidence for Long-Term Spatial Displacement of Breeding and Pupping Harbour Seals by Shellfish Aquaculture Over Three Decades,” and be none the wiser. 

To read Senator Dianne Feinstein’s complete September 2 letter to Interior Secretary Ken Salazar, go to our website, www.ptreyeslight.com. Click on “Seal study debunked by scientists” and then the link to the letter at the bottom of the page.