The Lower Columbia River Northern Pike Suppression Report (LCRNPSR) provides a sobering glimpse into what lies in the depths and shallows of the Robson Reach portion of the mighty Columbia River.
The report, released by the Ministry of Forests, Lands, and Natural Resources Operations (MFLNRO), confirms what many suspected; the northern pike population in the Columbia River is growing substantially and is a significant threat to native and non-native fish and the river’s blue-ribbon fishery.
Following a 2014 gill-netting initiative undertaken by Jeremy Baxter of Mountain Water Research and Matt Neufeld of the MFLNRO, the report estimates that the Columbia River pike population has ballooned to approximately 725, with a low-end estimate of 500 and a high estimate of over 2,700.
“The increase of Northern Pike poses significant threats to the Columbia River ecosystem including predation of native species, introduction of a wide variety of parasites and diseases, and competition with other species for common food resources,” states the report.
“The current gill-netting suppression program has helped to eliminate approximately 20 per cent of the northern pike population, but more rigorous efforts may be required to control this invasive species before they get significantly established.”
Under the direction of Neufeld and Baxter, fisheries technicians set nets over 16 days in May, August, and November of last year, netting a total of 133 pike that measured between 14 and 38 inches (37-96 cm.), and weighed up to 21-pounds (9.85 kg).
While the report clearly reveals the scope of the pike problem and its implications, Neufeld says an actual plan to address the problem has yet to be hammered out.
“We don’t quite know what that program is going to look like yet,” said Neufeld in an interview earlier this week. “As you read in that report, it looked somewhat hopeful that a removal program would have some meaningful impact on population size, but we’re still working out the details.”
The pike made their way into the Columbia from the Pend d’Oreille Reservoir, where a pike suppression program has been ongoing for a number of years.
The Columbia River gill-netting study was a small sampling compared to the efforts in the U.S. portion of the Pend d’Oreille River in Box Canyon where over 16,000 pike have been removed in the past three years.
“That (the Columbia program) was a first stab at the feasibility - certainly 20 per cent of the fish there isn’t trivial, but certainly not enough to have a significant impact,” said Neufeld.
The suppression effort undertaken by the Washington Department of Fish and Wildlife (WDFW) and the Kalispel Tribe Natural Resources Department (KNRD) has reduced the pike population in Box Canyon by about 90 per cent, primarily through a rigorous springtime gill-netting program.
The Box Canyon population increased from a count of approximately 400 in 2006 to more than 5,500 in 2010, while most other species declined significantly during that time.
This example provides ample warning for local fisheries as the potential threat northern pike populations pose in the Columbia, and possible spread through the Arrow Lakes Reservoir.
Pike were first detected in the Lower Columbia in 2009, when five were caught during a fish survey undertaken by Golder Associates.
MFLNRO addressed the problem by changing regulations to permit unlimited retention quotas, as well as introduce an angler-pike-reward program in 2013, in which PIT tags were embedded in the heads of 30 pike caught then released. It encouraged anglers to target pike and return heads to fisheries. Those with an embedded tag would garner a $500 reward.
The pike-reward program expired in March of 2014, but the response proved satisfactory as fisheries received 21 heads, yet none with PIT tags. However, last year’s gill-netting initiative caught six pike with PIT tags intact enabling biologists to calculate high growth rates.
Neufeld says MFLNRO is working with invasive species specialists from the Ministry of the Environment as well as partners like Teck, B.C. Hydro and others to determine funding and the most cost-effective method of extraction.
“I think overall the next steps are validating that it (gill-netting) will be a feasible option for control,” said Neufeld.
“This was a good first step at looking at that, but the details of that program we’re hoping to flesh that out in the next month or so.”
The report recommends that gill-netting suppression efforts in 2015 should continue on the Lower Columbia River and include sampling in both the Arrow Lakes and Pend d’Oreille Reservoir to determine how far the invasion has spread and whether or not spawning is taking place.
Furthermore, “Future programs should continue to remove pike, and focus on identifying the feasibility of control.”
The report also proposes that larval fish sampling be done near Norns Creek to see if northern pike are spawning successfully, or if the current population results from pike outside the main stem of the Columbia River.