Spokane, WA Weather

Saturday, December 31, 2011

WDFW Aquatic Invasive Species, Northern Pike

Esox lucius (Northern pike)

Animal Fish
Family: Escocidae
Classification: Prohibited (Northern pike in Washington are classified as both a game fish and a prohibited species, a current regulation proposal seeks to declassify them as a game fish. For more information, see http://wdfw.wa.gov/news/oct1911a/.

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Northern pike have become established in Box Canyon Reservoir on the Pend Oreille River and are considered a threat to other species, both native and non-native.  Their voracious appetite for other fish create a potential for great ecological and economic damage both in Northeast Washington and anywhere else they might become established.  In summary:

Recent biological surveys have documented a rapid increase in the number of northern pike in the Pend Oreille River, along with a reduction in the abundance of forage species such as native minnows and non-native sunfish and yellow perch.
The current distribution of pike in Washington includes Box Canyon and Boundary Reservoirs on the Pend Oreille River and the Spokane River from Lake Coeur d’ Alene in Idaho to Lake Spokane (Long Lake) in Spokane County.  There have also been several pike caught on hook and line in the Columbia River upstream from Kettle Falls.
The immediate concern is increasing numbers and distribution to the point of impacting vulnerable native species of trout, other game fish and non-game fish and even salmon and steelhead further down the Columbia River system.
Current management goals include minimizing impact to the native fish species and reducing the numbers of pike in the Pend Orielle system.
WDFW will also actively work to prevent the further illegal introductions of pike into other waters.
WDFW encourages sport anglers to assist in reducing pike numbers by harvesting pike from the Pend Oreille River system, particularly fish in the 20-30” range. This can be accomplished individually or by sponsoring or participating in a fishing contest (tournament).  To learn more about fishing contests in Washington, see http://wdfw.wa.gov/licensing/fishing_contests/.
Biological surveys, conducted between 2004 and 2011 have documented a rapid increase in the number of northern pike Esox lucius in Box Canyon Reservoir on the Pend Orielle River in northeast Washington. In addition, over the same period of time, the surveys showed a reduction in the abundance of forage species such as native minnows as well as non-native sunfish and largemouth bass.  This is a serious concern for all fisheries management entities in the Northwest because northern pike are both top-end predators that are known for over-feeding on their prey base and prolific spawners when the proper habitat is available.  Box Canyon Reservoir contains optimal spawning habitat for northern pike and they appear to be taking full advantage.  The Pend Orielle River is a tributary to the Columbia River, so movement of pike from Box Canyon Reservoir via downstream migration and illegal introduction to other waters by “bucket biologists” is also a grave concern and represents a threat to the region both biologically and economically.

Current distribution of northern pike in Washington State.
The northern-most red line represents the Pend Orielle River (Box Canyon and Boundary Reservoirs) and the Columbia River from the Canadian border to just north of Kettle Falls. The southern-most red line represents the Spokane River and Lake Spokane (aka Long Lake). The northern and southern red circles represent Newman Lake and Liberty Lake, respectively, in Spokane County. Further movement downstream in the Columbia River and illegal movement by “bucket biologists” is a grave concern of fisheries management agencies throughout the Northwest.
Northern pike in the Pend Orielle River (and Box Canyon Reservoir) are the result of illegal stockings in the Flathead, Bitterroot and Clark Fork River systems in Montana. From there, the pike migrated downstream into Lake Pend Orielle, then into the Pend Orielle River through Idaho and into Washington.  In the last couple of years their movement has carried them further downstream into Boundary Reservoir and with the high water levels of 2011, into the Columbia River. Anglers reported catching pike in the Columbia River during the summer of 2011 just north of the border in British Columbia, near Northport in Washington and near China Bend, just upstream of Kettle Falls.

There are many case histories across the country of pike populations which have overpopulated, resulting in over-feeding on their prey base (other fish).  This in turn results in “stunting” of the pike, which means their growth slows and they become skinny from lack of food.  This does not, however, slow down reproduction. An overabundant, stunted population of northern pike is not only detrimental to other species in the fish community, but they are undesirable as a sport fish (the average size is too small and they are too skinny).  Left unchecked, northern pike could have severely negative impacts not only on other desirable sport fish, but also on efforts to restore native fish populations such as westslope cutthroat and bull trout in the Pend Orielle drainage.

Northern Pike vs Tiger Muskie:
Know the Difference

Washington State now has both northern pike and tiger muskies inhabiting public waters. Both fish are “esocids”, which means they are members of the esocidae family. Other members of that family include muskellunge (true muskie) and pickerel. All share a similar, long body shape, oval in cross-section (hence the name “pike”, meaning spear or lance-shaped) and have a large duck-bill mouth with big teeth and a dorsal fin located near the tail fin. Learn more >>
Although the immediate concern is predation on native fish and other game fish in the Pend Orielle River, native salmon, steelhead and other species could also be at risk if pike were to become established further downstream in the Columbia River.  In addition, illegal introduction of pike into other lakes or rivers is a major concern.  Illegal introductions can potentially devastate ecosystems, other sport fishing opportunities and local and state economies.

The Washington Department of Fish and Wildlife (WDFW) is actively working to prevent the further spread and illegal introduction of northern pike.  Current management goals include minimizing impact to the native fish species and reducing the numbers of pike in Box Canyon Reservoir.  The WDFW is working closely with the Kalispel Tribe Natural Resources Department (KNRD) to develop the best management strategy for this population.

Two public meetings were held in April, 2011 which presented an opportunity to provide WDFW with feedback, ideas, opinions and concerns about the pike population in the Pend Orielle River (see summary of public comments). A presentation was given by WDFW and KNRD staff explaining the current situation in Box Canyon Reservoir. Afterwards, questions and comments were taken from the public and are being considered for integration into the future management of pike in Box Canyon Reservoir.

In April through June of 2011, WDFW and KNRD conducted three biological surveys in Box Canyon Reservoir, each with a different objective. The first, “Spring Pike Index Netting” (SPIN) was a repeat of a survey in 2010, designed to track the “relative abundance” of the pike.  It tells us if the population is increasing, decreasing or staying about the same (see survey summary). The second survey, a “Standardized Warmwater Survey”, designed to provide a representative picture of the overall fish community in the reservoir, and is used to assess the relative abundance of other fish populations in order to ascertain whether, and to what degree, pike are impacting those populations (see survey summary). The third survey, a “Pilot Removal Project” was designed to determine the timing of pike spawning activities in the reservoir and whether or not removal by gill netting is a viable control measure for managing pike in Box Canyon (see survey summary).

Other states in the Western U.S., including Alaska, that have non-native populations of northern pike, are facing challenges similar to Washington.  Although northern pike are native to much of Alaska, they are not native to the south-central part of the state where they have been illegally stocked and are considered invasive.  Pike have caused severe damage to native trout and salmon runs in several south-central Alaska watersheds and Washington is trying to learn from those events in order to prevent similar damage from occurring here.  Considering the high value of native trout, salmon and steelhead fisheries in both states, the Alaska experience is very relevant to Washington.  For more information on northern pike in Alaska, please see the Alaska Department of Fish and Game northern pike website.

There are two 2011-2012 sport rule proposal changes that could affect northern pike in Washington if passed into law: declassification of pike as a game fish and allowing a two-pole endorsement for Box Canyon and Boundary Reservoirs on the Pend Orielle River (Learn more about these two proposals). If you would like to comment on these or other sport rule proposals, please go to http://wdfw.wa.gov/news/oct1911a/ .  Although the public meetings have already taken place, follow other links and instructions on that page to provide your comments until December 30.

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