COLUMBIA RIVER — More spring Chinook salmon will be heading upstream to the Upper Columbia and Snake rivers in 2018 compared to this year’s runs, according to an early forecast of fish returns by the US Oregon Technical Advisory Committee.
The health of these upriver runs plays an important role in determining how any salmon can be kept by recreational fishermen in the westernmost stretch of the Columbia, and how long seasons are allowed to go on.
TAC is forecasting a spring Chinook run of 166,700 fish, slightly higher than its 2017 forecast of 160,400 fish and considerably higher than the actual run of spring Chinook this year of 115,822 fish as tallied at Bonneville Dam.
Willamette River spring Chinook are forecast by the Oregon Department of Fish and Wildlife to arrive in about the same numbers as the actual 2017 spring run. ODFW is forecasting 53,820 adult and 2,130 jack spring Chinook returns to the Willamette River. The early 2017 forecast was for 40,200 fish (later modified to 38,100 fish), but the actual run was higher at 56,163.
TAC is forecasting a run of 67,300 Upper Columbia River summer Chinook in 2018. Its 2017 forecast was 63,100 and the actual run was a bit higher at 68,204 fish.
Some 99,000 sockeye are predicted to enter the river in 2018. Last year’s early forecast was 198,500, which was modified in-season to 101,600, and the actual return was a dismal 88,263 fish.
Of the spring Chinook, some 20,100 will head into the Upper Columbia River, with 3,400 of those expected to be wild fish. That compares to the 2017 forecast of 19,300 (3,700 wild) and an actual run in 2017 of 11,166 fish (2,514 wild).
TAC is predicting a run of spring/summer Chinook into the Snake River of 107,400 fish (18,500 wild), more than twice the actual run this year of 51,948 fish (6,261 wild). The early 2017 forecast of spring/summer Chinook into the Snake River was 95,800 fish (15,100 wild).
Of the anticipated 99,000 sockeye, just 600 are expected to head to the Snake River. Last year TAC forecast a return of Snake River sockeye, listed as endangered under the federal Endangered Species Act, of 1,400 fish. However, the actual run was much Lower at 445 fish.
The remaining sockeye will head up into the Upper Columbia River. The Wenatchee River will get 25,700 in 2018. Last year’s forecast was 54,200 but the actual run was 34,861 fish.
Washington fisheries biologists are predicting the highest run of spring Chinook into the Lewis River since 2007. The Washington Department of Fish and Wildlife predicts a run of 3,600 fish in 2018. Last year’s prediction was 700 fish and the actual run was a much higher 2,400 fish. WDFW says that “Modified release strategies starting with brood year 2013 may be contributing to the increased returns.”
WDFW is also forecasting in 2018, 5,000 spring Chinook into the Cowlitz River. The 2017 forecast was 17,500 fish and the actual run was 14,000. The forecast for 2018 is about half of the 10-year average.
Kalama River projections are for 1,400 fish, near the 10-year average. The 2017 forecast was 3,100 fish and the actual run was 2,500.
According to Stuart Ellis, harvest management biologist with the Columbia River Inter-Tribal Fish Commission (he is currently TAC chair), the forecasts are largely age-based. Each age group is used to predict the next oldest age return. The individual age based forecasts are then summed to produce a total expected adult return. Jacks are the youngest age group used and often predict the largest portion of the run.
“We use age data collected at Bonneville, in the fisheries, and in escapement areas to estimate the past returns by age which are then used in forecasting” Ellis said. “One of the most common forecast methods is to do statistical regressions between the ages. Sometimes we use ratios. We look at relationships between various time periods too.”
TAC also looks at environmental information, such as ocean conditions, when making forecasts, he said.