FISHERIES -- Pink salmon have set a record for wandering into the Columbia River and upstream over Bonneville Dam.
The spectacle has left fisheries biologists scratching their heads, since they don't know of any resident pink salmon populations in the Columbia Basin.
Also known as humpbacks or humpies, the pinks known to have a relatively high incidence of straying to spawn someplace other than their natal stream, according to the Columbia Basin Bulletin.
More than 1,500 pink salmon have been counted climbing over Bonneville’s fish ladders, easily surpassing the previous high count -- 637 in 2003 -- for the entire late summer-fall season, and the highest count since at least 1938, Washington Fish and Wildlife Department biologists said today.
Read on for details and possible explanations from the Bulletin's story.
The highest up in Columbia-Snake hydro system that pinks have been seen this year so far is Ice Harbor Dam on the lower Snake River, where a single humpy has been counted.
The pink salmon are the smallest in stature of the six salmon salmon that ply the Pacific Ocean, but they are also the most abundant. They can be found in spawning streams all around the Pacific Rim, including as far south as northern Japan. In North America, pink salmon populations regularly occur in marine waters as far south as Washington state and spawn as far south as Puget Sound and the Olympic Peninsula.
Pinks are spotted almost annually at Bonneville, but typically in small numbers. The total was six last year. Only six times on a record dating back to 1938 has the pink count at Bonneville totaled more than 100. All but two of those 100-plus counts have been in odd-numbered years. The Bonneville pink count in 2000 and 2002 was zero.
Biologists note that even- and odd-year broodlines are characteristic of pink salmon throughout their natural range. The pinks head for the ocean soon after emerging from their nests. They then return to spawn as 2-year-olds.
Because of their relatively strict two-year life cycle, one year's produce does not interbreed with the next year's.
According to a species status review by the National Marine Fisheries Service completed in 1996, most of the pink populations found in northwest Washington are odd-year fish.
Nearly six million pink salmon are expected to return to Puget Sound this year. That forecast is 3 million salmon below 2009’s record return but still an abundant run.
And the return just north of the border to British Columbia’s Fraser River was expected to total 17 million.
So some fish might have wandered south. The autumn spawners are not known to have self-sustaining populations in the Columbia basin. But they are spotted here and there.
“We pick them up every once in a while during spawning surveys,” said John North of the Oregon Department of Fish and Wildlife. “But it’s pretty rare.”
The humpbacks have been seen in such rivers as the Cowlitz, Kalama and Sandy, which empty into the Columbia below Bonneville, and the Wind, which joins the big river in the Bonneville pool.
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.