Pink salmon are a species whose presence is so subtle and slight in the Columbia River that it gets little or no mention in state literature or regulations.

But they are back again this year, and marching to the beat of a different drummer. Through Wednesday 52 pink salmon – the smallest of six Pacific salmon species – had been counted passing Bonneville Dam.

Famed in Alaska, Canadian and Puget Sound streams, the autumn spawners, also called humpbacks, are not known to have self-sustaining populations in the Columbia River basin. But they are spotted here and there.

"Pinks are found in the Columbia during odd numbered years; some of the largest numbers (possibly a few hundred fish) are found in the lower Cowlitz," according to Joe Hymer of the Washington Department of Fish and Wildlife. The humpbacks have also been identified hunting spawning grounds in such tributaries as the Kalama, Wind and Sandy rivers, he said.

"They're kind of an oddball. They do exist to some degree" in the basin, Hymer said.

"However, it is very unusual to find pinks in the Columbia during even numbered years," he said. It's also early to find them in the river. The first was counted passing Bonneville July 2.

This year's humpback appearance "is much earlier than the last five years," said John North of the Oregon Department of Fish and Wildlife. In 2007 the first pink appeared in the fish ladder count window on Aug. 3.

Likewise for another species -- chum salmon. Five have been counted at Bonneville already. They typically enter the river in October and November.

A handful of "summer" chum are found in the Cowlitz almost every year, Hymer said.

State officials sampling treaty Indian commercial harvests confirmed pinks had been caught above Bonneville Dam. Hymer said they were smallish fish, perhaps 2 or 3 pounds

The pinks have been a regular at Bonneville's fish ladders since 1941, three years after the dam was completed and counts began. The annual count never rose above 50 until 1965, according to data posted by the Fish Passage Center.

The most ever counted was 637 in 2003. There are numerous zero counts, mostly in even numbered years. The total count last year was 27; in 2006 it was 6; in 2005 it was 17, and in 2004 it was 1.

When spawning, males develop humped backs, hooked jaws and reddish-yellow sides. The females tend to be more greenish. The pinks can be up to 30 inches in length and weigh up to 12 pounds, but usually weigh from 3 to 5 pounds.

Pink salmon begin their downstream movement almost immediately upon emergence from the gravel and move rapidly into near-shore nursery areas and shallow marine waters. For a short time, pinks may be abundant in estuarine tidal channels; however, pinks typically spend minimal time in estuaries. After about 18 months at sea, pinks return to their natal streams to spawn. Usually those streams are not too far from the ocean.

Because of their relatively strict two-year life cycle, one year's produce does not interbreed with the next year's.

Important spawning populations occur from the Puyallup River in Washington northward to Alaska and eastward to Canada's Northwest Territories," according to a Pacific States Marine Fisheries Commission fact sheet. A web search found little about Columbia basin pink salmon, although one site referenced them as one of six historic stocks and called the basin humpbacks extinct.

"Ocasionally we get pinks. They don't belong in the Columbia," said Mike Matylewich, head of the Columbia River Inter-Tribal Fish Commission's fishery management department. "They're not a spawning population."

He and Hymer said they are likely fish that have strayed southward.