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Council member rips ecosystem study off Oregon Coast

Critics of marine reserves often contend the are not squarely based on science. One big problem is the lack of science. The amount of knowledge about the impacts of commercial fisheries on the ocean ecosystem is relatively sparse, scientists say.

But sometimes, political leaders do not welcome the advent of new science. This year, a significant peer-reviewed study was published that expanded what we know about the effects of bottom trawling on seafloor habitats. But instead of greeting this new science with enthusiasm, a member of the Pacific council and the Oregon Department of Fish and Wildlife attempted to stifle the report.

Mark A. Hixon of Oregon State University and Brian N. Tissot of Washington State University found significantly more species on untrawled seafloors, an important but not unusual finding for policy makers interested in knowing the impacts of these fisheries.

Hixon and Tissot closely examined Coquille Bank, a muddy seafloor about 40 miles off the Oregon Coast, between Bandon and Cape Blanco, up to about 360 meters deep. “We observed 23 percent more fish over untrawled compared to trawled seafloors, and recorded 27 fish species on untrawled bottoms, but only 19 species on trawled seafloors,” Hixon and Tissot write in their peer-reviewed paper, published in December 2006 in the Journal of Experimental Marine Biology and Ecology.

In untrawled areas, they found such species as sea pens, ratfish, sablefish, ronquil, slender sole, and poacher. In trawled areas, they found species known as mobile scavengers that may aggregate along trawl-door tracks.

Among the species most directly reduced by trawling on deep mud seafloors were sea pens, the research found. Also known as sea whips, these are soft-bodied, erect organisms that anchor in the seafloor and project upwards as much as 3 feet, forming forest-like stands. Sea pens, which can live up to 50 years, were nearly absent on trawled bottoms.

The study appeared to be the first to examine trawling impacts on the muddy seafloors commonly found beneath the California Current.

“In the region managed by the Pacific Fisheries Management Council — federal waters off Washington, Oregon, and California — there has been only a single published study that compared trawled vs untrawled areas,” Hixon and Tissot wrote.

Just south of Monterey Bay, Calif., scientists examined a lightly trawled area near-shore, and a heavily trawled area further out. Their study, published in 1998, found higher densities of epifaunal species — species that are attached to the bottom, like sea pens.

Until the Hixon and Pissot study, they said “virtually nothing was known of bottom-trawl effects on the predominant trawled habitat off the U.S. west coast: mud seafloors of the outer continental shelf. Seafloors off Oregon have been subjected to higher bottom-trawling effort than those off Washington and California.”

Their findings squared with other research showing that “bottom trawling has substantial impacts” on stable deep mud habitats similar to those at Coquille Bank.

“This ecosystem shows striking differences between trawled and untrawled areas,” said Tissot, an expert in seafloor organisms. “Areas that had obviously not been trawled were covered by forests of sea pens and other marine life, and the trawled areas looked like a desert, crisscrossed with trawl tracks.”

After Hixon and Tissot published their study, the Oregon Department of Fish and Wildlife responded with sharp criticism in a review.

“The evidence presented in this paper was inconclusive and should have been couched in language to address statistical and sample comparison problems,” the ODFW review said.

ODFW cited a number of differences between the untrawled and trawled sites, and other alleged inaccuracies, that led it to question the study.

“Staff determined that this paper is not adequate for the purposes making conclusions and should not be used to drive management decisions,” the agency said. “Other research by other authors which is cited in this paper offers more solid results of trawl effects on fish and invertebrate assemblages on habitat.”

Frank Warrens, a member of the Pacific Fishery Management Council, ripped the peer-reviewed study. “When industry members reviewed the study based on very limited sample size and observation duration,” he said in an email, “they turned up several errors and disputable data in the study that will need to be reviewed further. In short the study is not ready for prime time.”

Warrens acknowledged that he represents “the fisheries side of the issue.”

In response, Hixon and Tissot defended the study and its results, denied the existence of any errors, and highlighted the lack of cooperation they received. They requested data regarding the efforts of trawlers, but received no information. Oregon Sea Grant, a state agency, rejected two small grants for mapping seafloor trawling tracks.

The authors said the “overly negative review” by the state “will serve only to further entrench denial within the Oregon trawl industry regarding the widely documented adverse impacts of bottom trawling on seafloor habitat. We invite everyone concerned to set aside any assumption that the effects of trawling off Oregon are somehow substantially different from those documented elsewhere in the world.”

It’s all about the ecosystem 1 | 2 | 3 | 4 | 5

Council member rips ecosystem study off Oregon Coast

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