The halibut fishery of the North Pacific -- long touted as a model for wise fisheries management and the goodness of privatizing commercial fisheries -- is now in such dire straits regulators were Wednesday talking about the possible need to cut harvests to levels not seen since the 1930s.

The problem? Adult flatfish are disappearing from the population at unexplainable rates, the International Pacific Halibut Commission was told Wednesday at a meeting in Seattle.

Adult fish comprise what the scientists who work for the commission call the "exploitable biomass." These are the halibut capable of breeding and reproducing.

These are also the fish targeted by commercial fishermen.

"Seventy percent of the total commercial catch is female," commission lead biologist Steven Hare said. The most common halibut caught by commercial longliners, according to commission studies, are 12-year-old females. Those fish comprise more than 15 percent of the entire commercial catch. If life has gone well for such halibut, and they've grown fast enough, they'll likely get to spawn once before they're killed. Commission studies indicate about 50 percent of females reach sexual maturity by age 12.

Those that live to be 13 have an even better chance of getting to spawn, but they are also heavily harvested. They comprise more than 10 percent of the commercial catch, according to Hare. All told commercial fishermen take more than a quarter of the allowable harvest of halibut just as the fish are fully reaching spawning age.

But that is not the real problem at the moment, Hare said. The real problem is what he called "unspecified mortality." Halibut are disappearing from the population for reasons managers can only guess at. "It's troubling," Hare said.

Were managers to take these mystery disappearances fully into consideration, he added, they would be forced to recommend drastic cuts in commercial harvests.

One model that does this, he said, suggested setting catches "28 percent lower than the lowest level since 1935." Catches, or at least legal catches, have already been pushed down 55 percent in the past decade, and they are for sure going down again.

The only real question is how far down.

Hare did not go into the possible reasons for the mysterious decline in what might be called eating-size halibut, but others have. There is a long list of possibilities -- disease, starvation due to competition for food and, of course, overfishing in any of a variety of forms:

• Dead halibut discarded in the halibut fishery itself because they are too small or don't look good -- what the commission calls wastage.
• Dead halibut discarded in trawl fisheries -- what the North Pacific Fisheries Management Council calls "bycatch.'' Federal law prohibits keeping these fish so as to discourage the big boats dragging trawls nets for pollock and Pacific perch from targeting more valuable halibut.
• Dead halibut discarded from longline fisheries that are supposed to be catching other species of fish, such as sablefish, but catch a lot of halibut anyway.

Illegal fishing?

And there is always the possibility of good, old-fashioned, illegal fishing. Privatization of the halibut fishery was supposed to put an end to this. It gave halibut fishermen an ownership interest in the fish. This was called the individual fishing quota, and it was supposed to help make the average commercial halibut fishermen into a wise steward of the resource.