Alaska Fish & Wildlife News
Problems with Pike
Why We’re Removing them from the Kenai Peninsula
My twelve-year-old knees were trembling as I stood in waist deep grass along the bank of Coon Creek. The fish that just tried to swallow my red-and-white daredevil spoon was a monster. I saw its wake trailing behind the spoon and, when it tried to inhale it, I reacted too fast and jerked the lure out of its white mouth before it could close down with its over 700 teeth. I had no idea that this urban Minnesota creek could contain such a beast. That northern pike was the largest fish I’d ever seen, and its mouth was large enough to stuff a softball in. Despite repeatedly casting back to the same spot, I never saw that fish again, it sank like a submarine back into the dark cut bank it came from.
Fast forward to my college years and I was guiding catch-and-release fishing trips for northern pike on a remote Yukon River tributary. One of those fishing trips resulted in surgery to repair a severed tendon in my hand, a byproduct of me getting in the way of those razor-like teeth. Later, after moving to the Kenai Peninsula, I was initially excited to learn that northern pike were available in some local lakes, although I heard they were newcomers to the area. Eventually I learned that pike were not a native species to most areas of Alaska southeast of the Alaska Mountain Range. I also noticed most of the pike on the Kenai Peninsula ran on the small size which was a bit disappointing for someone so spoiled from catching monsters in the Interior. I was lucky and landed a job as a fishery biologist for the Alaska Department of Fish and Game, Division of Sport Fish in Soldotna. In this position I learned much more about our Kenai Peninsula pike, and I began to see firsthand some not-so-good consequences resulting from this introduced species.
The history of northern pike in Southcentral Alaska is a bit muddy, but this is what we know. Pike were likely first introduced to Bulchitna Lake in the Susitna Drainage in the 1950s. From there, they naturally spread throughout much of this Iowa-sized drainage aided by more illegal introductions. Pike were first documented on the Kenai Peninsula in the Soldotna Creek drainage during the mid-1970s, and initial assessment work suggests Derks Lake was probably their ground zero. Since then, pike have been identified in 24 waterbodies on the Kenai Peninsula. According to Kristine Dunker, an ADF&G fisheries biologist specializing in invasive species, “to the north, pike have been documented in over 120 waterbodies in the Matanuska-Susitna Basin, and that list is rapidly growing.” Pike are utilizing Cook Inlet to travel down the west side of the inlet where commercial setnetters occasionally capture them. Pike have a degree of tolerance for saltwater, and in some parts of the world like the Baltic Sea they live their entire lives in brackish water. Fortunately, pike are not showing up in east-side setnets of Cook Inlet. Emerging genetic analysis is trying to shed some light on how pike got to the Kenai Peninsula and where they came from. For example, according to Dunker, “there is some evidence suggesting that pike, in at least one lake on the Kenai Peninsula, are more genetically similar to pike in Lake Iliamna than other introduced pike populations in Southcentral," lending support to a rumor that a pilot flew them in from that region.
So, what is the big deal with having pike on the Kenai Peninsula? There has been a fair amount of chatter about pike being an invasive species in these parts and how devastating they can be to native fish populations like trout and salmon. Despite this rhetoric, pike in their native Alaskan range appear to coexist just fine with these same species in places like Bristol Bay and many of our big Interior drainages. Intuitively this doesn’t exactly make a lot of sense. Bear with me as I dig a little deeper and explain why pike are a big deal to our local native fish and why they are an invasive species in Southcentral Alaska. Pike are ambush predators; they typically make a living darting out of weed beds to catch unsuspecting prey. In places where there isn’t much weedy, slow-moving water, pike are less efficient ambush predators. Deep or fast-flowing water can serve as a refuge for prey because few pike inhabit that niche, and the pike which do, tend to be larger pike that often feed on prey bigger than juvenile trout and salmon. Looking at fish survey data from Interior Alaska, it is striking how few juvenile salmonids coexist with pike in the countless shallow floodplain lakes common to the region, despite connectivity to anadromous rivers. In these habitats, as a top predator, pike naturally shape what the fish communities in these areas look like.
In Southcentral Alaska, we have a lot of shallow vegetated lakes and streams that for thousands of years have served as nurseries for juvenile trout and salmon. These fish evolved here in the absence of a large, top of the food chain predator like pike. In terms of vulnerability, examples are the canoe routes in the Swanson and Moose river drainages on the northern Kenai Peninsula, or the many lakes in the Soldotna Creek and Beaver Creek systems that have historically been rich in native trout and salmon, but they are also ideal pike habitat. I have seen firsthand how pike predation can collapse native fisheries in situations where pike and native fish habitat preference overlaps. According to Dunker, “we have seen this in plenty of other waters in Southcentral Alaska too, like Alexander Creek, where one of the Mat-Su’s most popular king fisheries is now essentially gone.” Here on the Kenai Peninsula, it is unlikely that our fast-flowing glacial rivers and deep sockeye rearing lakes would support large pike populations because there is limited suitable pike habitat. Looking at how pike coexist with salmonids in Lake Iliamna and Bristol Bay’s Wood-Tikchik lake system, their impact to the largest sockeye fishery in the world is modest due to the scarcity of the habitat they require.
On the Kenai Peninsula, invasive northern pike have completely eliminated native rainbow trout, Dolly Varden, juvenile coho salmon and even threespine sticklebacks from multiple lakes in the Soldotna Creek drainage where water depths rarely exceed 25 feet. Northern pike nearly caused the localized extinction of Arctic char and rainbow trout in Stormy Lake near Nikiski. Recent research in Alaska has documented that smaller pike feed most heavily on juvenile salmonids when available, and if the juvenile salmon supply runs out, they will shift to feeding more on other species like stickleback, sculpins, insects, frogs and mice or even cannibalize each other. Once the richest prey resources like trout and salmon are depleted, pike growth often stunts.
My primary job duties for the last ten years have focused on protecting our native fisheries from invasive northern pike on the Kenai Peninsula. To that end, we have mostly used nets and rotenone (a plant-based fish pesticide) to remove them. In most instances, complete eradication of pike from a waterbody is not feasible with gillnets alone and treating the waterbody with rotenone is the only option with a high likelihood of success. We have demonstrated that rotenone treatments can be done safely and effectively while also following rigorous permitting requirements.
In 2008 we began eradicating pike populations on the Kenai Peninsula with rotenone, beginning with Arc Lake, and Scout Lake followed in 2009. In 2012, we removed pike from Stormy Lake near Nikiski, and between 2014 and 2017, we eradicated pike from the Soldotna Creek drainage by treating Derks, Union, East Mackey, West Mackey, Sevena and Loon lakes and the flowing waters of Soldotna Creek. The Soldotna Creek project involved an extensive native fish restoration effort as well. Following all these local pike removal efforts, there are now just eight known Kenai Peninsula waterbodies with pike, and all are in close proximity to each other, about five miles south of Soldotna near Tote Road. Fortunately, these lakes do not connect to waters with wild salmon or trout. An argument could be made for leaving these pike alone; some anglers enjoy catching them, so why remove them if they aren’t directly threatening wild fisheries? The simple reason is that those pike provide an easy source for illegal introductions elsewhere.
I often hear that Kenai Peninsula pike are probably spread more by natural mechanisms than by people intentionally releasing them. Pike eggs are sticky and are broadcast on standing aquatic vegetation about the time lake ice goes out in the spring. The theory is these sticky eggs could cling to airplane floats, duck or moose legs and then fall off in nearby waterbodies and kick start new populations. Conceivably eagles could drop a live pike into a waterbody too. Any of these unintentional mechanisms are possible but must be extremely rare or we’d likely see a different distribution of pike than we have. Instead, all 24 pike waters identified on the Kenai Peninsula have road or trail access or they are connected to another pike lake by surface water. If live pike, or their eggs, were easily dispersed after being carried by animals or attached to airplane floats, their distribution on the Kenai Peninsula would be far more expansive than these 24 readily human-accessible waters we’ve found them in.
Just last summer, the division confirmed the existence of pike in four new lakes on the Kenai Peninsula. Most of these recently discovered pike populations are clearly the result of human introductions. In fact, the identities of some people suspected of releasing pike have been reported, but proving these crimes is a challenge. The State of Alaska treasures our incredible wild fishery resources. So much so that it is a Class A misdemeanor to transport any live fish without a permit. In addition, civil penalties could seek to recoup the costs needed to remove introduced pike which could cost the culprit hundreds of thousands of dollars. Luckily, we moved quickly and have already removed pike from two of the four newly identified pike waters.
So, what typically happens after invasive pike are removed? In most instances the waters are restocked by ADF&G with the same wild native fish species historically found there. In some cases that might be just sticklebacks. In other instances, it could include stocking wild juvenile salmon, rainbow trout, Arctic char, Dolly Varden and/or sculpins. In other situations, particularly in lakes previously stocked with hatchery fish, hatchery stocking resumes the summer following the eradication. I frequently receive feedback from residents living on lakes where invasive pike were removed and hear things like “…we see more birds and frogs near the lake and see fish jumping regularly...”. Simple observations like these suggest the ecological balance of these lakes has improved. Where ADF&G has removed pike from waters connected to other waters still supporting wild fish populations, it has been amazing to see how quickly natural native fish recolonization occurs. Lakes that almost exclusively supported just pike now support thousands of rearing salmon and wild trout.
What can you do to help protect our wild fish resources from invasive pike? Probably the most useful thing is to retain and report any pike caught on the Kenai Peninsula unless it came from the known pike waters of the Tote Road area south of Soldotna. Reports can be made online at: http://www.adfg.alaska.gov/index.cfm?adfg=invasive.report or call 1-877-INVASIV.
If you enjoy fishing for pike, keep in mind most of the Tote Road area pike lakes are surrounded by private property so you must get landowner permission before entering. Pending permits, pike in the Tote Road lakes could be eradicated as early as the fall of 2018.
Occasionally ADF&G receives a report of a pike being caught or observed in a vulnerable area like the Moose River or Swanson River drainage. However, it has been many years since a new report of pike in either drainage has been verified. To date, there is no hard evidence that a reproducing pike population exists anywhere on the Kenai Peninsula outside the Tote Road area. Still, should a pike turn up somewhere unexpected, that information will be invaluable as early detection and a rapid response (EDRR) is the mantra for invasive species control.
Finally, I’d like to add that pike are not inherently bad fish. Pike just do what they are meant to do. Fishing for pike can be a great experience and pike can provide year-round fishing opportunities. Catching a big pike can still make my knees weak. However, the cost of having pike on the Kenai Peninsula is that native fish populations will continue to suffer, and some native fisheries would likely collapse again. The economic consequence of pike-induced fishery losses can be immense to communities dependent of fishing industries. If left unchecked, we would expect pike to eventually colonize important salmon rearing areas like the Swanson and Moose River drainages and result in dramatic decreases to coho salmon and rainbow trout populations.
For more information, call the ADF&G Soldotna office at 262-9368.
Rob Massengill is a fisheries biologist with the Division of Sport Fish and who lives in Kasilof and works in Soldotna.
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