The sleek and carnivorous fisher, a cousin of the weasel, has long been thought to favor old-growth forests, and its decline in the Sierra Nevada has been linked in part to logging that eliminated such habitat.
The Center for Biological Diversity petitioned the state to list the fisher as endangered.
The state Department of Fish and Game's recently published status review concludes the fisher does not warrant protection under the state Endangered Species Act, in part because of information that they appear able to survive in logged forests if some large trees are left uncut.
The outcome is politically sensitive. If the fisher is eventually recommended for protection by the state Fish and Game Commission, new logging restrictions could harm the timber industry.
Reginald Barrett, a professor of wildlife management at UC Berkeley and an expert on the fisher, on Friday sent the commission a 15-page critique of the final report.
Barrett in January reviewed a draft report, which he praised as supporting a conclusion to protect at least the southern Sierra Nevada fisher population as "threatened."
But in his Friday letter he called the final report "so different in content and tenor."
"It is evident that more emphasis was placed on timber industry input via personal communications and unpublished industry reports than the scientific literature," Barrett writes. "What I am concerned about is the fact that the Commission is being given a recommendation by DFG that has apparently gone beyond the expected biological, scientific information to include political and economic considerations."
Barrett did not respond to phone and e-mail requests for comment.
His letter highlights 21 sections that were deleted and 16 others added between the draft and final reports. The changes appear to strengthen arguments that the fisher population isn't harmed by logging, and to weaken support for protecting the species.
In numerous instances noted by Barrett, the final report deletes references to evidence that fishers depend on older and deeply shaded forests, and adds other information — largely based on unpublished studies — that fishers can survive in habitats altered by logging.
Eric Loft, chief of Fish and Game's wildlife branch, challenged as "not true" Barrett's suggestion that industry influenced the report. He said the report was an effort to provide the commission with the latest information — especially on the habitat question.
"Clearly, yes, it would be great if everything was peer-reviewed. But everything isn't peer-reviewed. It's the best available scientific information that we have," Loft said.
The reports are typically drafted by a staff-level biologist and then reviewed and finalized by department supervisors. In this case, the changes Barrett cites are alleged to have been made after staff completed the draft.
The draft was peer-reviewed individually by scientists, including Barrett. The final document has not received any peer review.
Loft said many of the changes referenced by Barrett were done to include information from a 2008 report, which evaluated the Center for Biological Diversity's original petition, so the two documents would be consistent.
"The draft document did undergo change to make sure we emphasized what we know ... versus what we think," Loft said. "We worked to avoid being overly speculative or draw conclusions that could not be substantiated by scientific information."
In a letter dated Friday, another wildlife biologist, Carlos Carroll, wrote the commission that the report "does not provide the level of scientifically rigorous review" needed for an informed decision.
Like Barrett, Carroll urges the commission to send the report back for more work.
"All I know is that the final report is not scientifically sound," Carroll told The Bee this week.
Much of the disputed anecdotal information came from a wildlife biologist who retired last year from Sierra Pacific Industries, the largest private landowner in California and a major player in the wood-products industry.
Sierra Pacific spokesman Mark Pawlicki denied that his company had any improper influence on the report.
"Here are the facts," Pawlicki said. "The Department of Fish and Game asked for more recent information that anyone has. We provided our input to the process just as other people have. Our input is no different than anyone else."
The Fish and Game Commission will discuss the report, and the fisher's conservation status, at its meeting April 7 in Monterey.