LEWISTON – An out-of-place fish showed up Sept. 22 at Lower Granite Dam.
A pink salmon was captured in the dam’s fish trap. It’s one of only a handful of pinks observed at the dam over its 46-year history.
Biological data was collected from the female fish, including a genetic sample that may allow biologists to determine where it came from, before it was set free.
Stuart Ellis of the Columbia River Inter-Tribal Fish Commission at Portland said it’s likely that the fish and others pinks documented in the Columbia and Snake rivers are from elsewhere in the Pacific Northwest.
“We think these fish are most likely stray fish from Puget Sound populations. Pink salmon there is a strong odd year return and a week even year return and that is kind of what we see in Columbia. This year, we saw 284 (at Bonneville Dam), last year it was two,” he said. “We pretty much think these fish are just exploring the outer bounds of their range.”
Although they have been documented spawning in places like the White Salmon and Hood rivers, according to Michele DeHart of the Fish Passage Center, there is no self-sustaining run of pink salmon in the Snake or Columbia river basins. Pink salmon, which are also called humpback salmon or humpies for short, are routinely observed in low numbers climbing fish ladders at dams on the Columbia River and, in rare occurrences, on the Snake River.
This year, 283 have been counted at Bonneville Dam on the Columbia River. That is the highest number since 410 were counted in 2013. The record high was notched in 2011 when 3,828 were counted there, according to the Fish Passage Center and the Columbia River Inter-Tribal Fish Commission.
Records by those agencies indicate three pink salmon were recorded at Ice Harbor and Lower Granite dams in 1991 and one at each of the dams in 2003. The Corps recorded 16 at Ice Harbor Dam in 2011.
According to a 1978 paper by National Marine Fisheries Service scientists Larry Basham and Lyle Gilbreath, pink salmon were observed at several locations on the Snake River in 1975, and one each was trapped at Little Goose and Lower Granite dams. Lower Granite Dam was completed that year. The authors believed that was the first recording of pink salmon on the Snake River. But they also noted fish counters at the dams don’t expect to see pinks and that the fish might sometimes be mistaken for other species.
The scientists also noted that five spawned-out pink salmon carcasses were found on the lower Tucannon River during fall chinook spawning surveys in 1975.
Pink salmon generally return to coastal rivers and, according to Gilbreath and Basham, rarely penetrate farther than 100 miles upstream. They said pinks spawn about 350 miles up the Fraser River in British Columbia, Canada. Lower Granite Dam is more than 400 miles from the Pacific Ocean.
“The fish may be remnants of a small Columbia River stock which may now be entering the Snake River system. It is unlikely that they are strays from a short-run coastal stock. However, they could be strays from long-run stocks such as those from the Frazier River system,” they wrote.
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