This paper was written as part of the 2001 Alaska Ocean Sciences Bowl high school competition. The conclusions in this report are solely those of the student authors.
The Pike Plague
Written in part by each
of the following:
AbstractThroughout history there have been many plagues of all different types and forms. Though the problem we are facing today is not a terminal disease or a swarm of locusts eating our crops, the problem we are facing in Anchorage, Alaska, is the plague of the pike. These voracious predators eat anything from small insects to birds sitting on a lake (Morrow, 1980). Pike have somehow been introduced into our local waters, and are eating the native fish. Some people do not even know that this is a problem, but it must be recognized as a problem and something must be done to fix it. If action is not taken, everyone in Anchorage could be affected by a declining economy due to the devastation of our native salmon and trout species.
There are a few possible causes as to how the pike was introduced into Anchorage waters. One possible explanation, according to Barry Stratton (pers. comm.) of the Alaska Department of Fish and Game (ADF&G), is that someone disagreeing with proposals made by organizations, such as ADF&G, sabotaged the waters by intentionally placing pike into the lakes to make a statement. Another plausible idea, also offered by Stratton, is that the pike were accidentally thrown into the water under the false pretense that it was dead. Pike have the uncanny ability to produce a protective, slimy coating to shield them from exposure for up to 13 hours out of water (VanRyn, 1999)! In our conversations with Stratton and Bosch (pers. comm.), they reported that in the 1940's and 1950's sport-fishing enthusiasts intentionally introduced pike into Mat-Su area waters. Then in the 1986 flood, the pike escaped and spread into other waters closer to Anchorage. Other possible explanations being offered, but not accepted by ADF&G, are that the sticky eggs of pike attach to animals and are transported to other areas, or that eggs are released from the floats of planes returning from fly-in fishing trips.
No matter how the pike made it to Anchorage lakes and streams, their presence causes concern over the survival of the native fish species, salmon and trout especially, and requires some measures to either severely limit their populations or to eliminate them altogether. Some possible solutions to the plague are to use the toxin Rotenone, deplete the oxygen levels in the lakes, increase public awareness with signs, seminars, bounties, stronger laws, changes in fishing regulations, and maybe even a derby. The solutions that are put into place will need to be repeated every few years because it is almost impossible to prevent foreign species from being intentionally introduced into Alaskan waters. ADF&G is currently seeking changes to strengthen the laws prohibiting the transport of live fish or live fish eggs (see Appendix i, 5 AAC 75.055.), and requesting $100,000 to be budgeted to implement and enforce these laws.
The 50-year environmental plan proposed by the Dimond High School NOSB team combines some of the ideas from ADF&G with some of our own ideas. We disagree with the use of Rotenone because it kills all gill-breathing organisms, but we agree with public education, strengthened laws, and increased angler pressures. We believe that there are enough freshwater anglers to promote a "Pike Day" to be held on the summer solstice, to encourage residents and tourists to participate in festivities centered around a derby, similar to the Seward Silver Salmon Derby, to raise funds, educate the public to the dangers of introduced species, and have fun catching the aggressive pike. We suggest an annual event until the pike population declines. When the numbers are not sufficient to support a derby, the "Pike Day" goal would be to determine if any pike, or other invasive species, are present, aiding the monitoring efforts of ADF&G. These activities would sustain public awareness and education, involve the public in fisheries management, and hopefully, eliminate the pike from our lakes and streams.
Northern PikeThe pike is a compressed fish with an elongated, flattened snout and large sharp teeth. They are vicious predators. Five species in one genus are distributed in the northern hemisphere. One species is confined to Siberia, three are native to eastern North America, and the fifth, the northern pike, Esox lucius, is of circumpolar distribution (Morrow, 1980).
The color of an adult is a dark grayish-green or dark brown, sides with numerous yellow spots arranged in irregular longitudinal rows, and the scales usually have tiny gold spots at the edge. The bottom and belly of the fish is a creamy white. The anal and caudal fins are green to yellow, sometimes more or less orange or red, marked with dark blotches. The head is dark green above and pale below, with dark lines running below the eyes. Young pike are similar in color, except that their sides are marked with irregular vertical lines instead of spots. The size of the northern pike reaches to 133 cm in length and 22.3 kg in weight.
There have been some pike found with a genetic mutation that breeds off-colored pike, called Silver Pike. This new breed of pike is similar to that of any other adult fish except that the sides are marked with irregular pale vertical bars instead of spots, and the color is grayish-green or deep blue on their back.
Pike have been introduced into a number of places in the U.S. and there is a growing angler interest in the preservation and encouragement of the species in warm water habitats. However, when the fish are introduced into a new environment, they can be more of a nuisance than a blessing, depending on one's point of view. It was thought that pike might be helpful in keeping the numbers of the other species under control, and thus preventing them from stunted growth as a result of overpopulation. The pike are so voracious that they eat everything that moves, including their own kind. The pike end up the only species left and suffer stunted growth (Morrow, 1980).
Pike live in a variety of habitat types. In the winter, the pike like relatively deep water in lakes and rivers. When spring approaches, they begin to move inshore or upstream to the shallow, marshy areas with muddy bottoms where they spawn. This movement takes place at night and not until the water temperatures in the shallows reach about 6-9 degrees C. Pike tend to return to the same place every year to spawn. Spawning occurs usually during daylight hours. Cloud cover, ripples on the water, or excessively cold temperatures reduces spawning activity (Lagler, 1966).
The eggs are .25 to .3 cm in diameter, and tan-yellow in color. Egg numbers increase with the size of the fish, from as few as 2,000 in females to about 33 cm long, to nearly 600,000 in a fish weighing 14.5 kg. Ripe females contain both large, ripe eggs and minute immature eggs that will ripen the following year. Thus new eggs are always developing during the life of the female. After fertilization, the sticky eggs settle to rest on the weeds or the bottom. Developing time to hatching varies with temperature. Active feeding begins when the young are 1.1 to 1.3 cm long (around ten days after hatching). As the young grow, they shift from eating zooplankton and insect larvae to other small vertebrates, and by the time they are about 5 cm long, the baby pike are feeding almost exclusively on other fish. The baby pike avoid prey such as sticklebacks because of their large spines, however mature pike often feed heavily on sticklebacks.
When the young have reached a length of about 2 cm they begin to move out of the marshes. Mortality from the fertilized egg to migrant fry is heavy, as much as 99.9%. Competition for food, predation and cannibalism are the most important factors here. Water quality is also important because the fry are rather sensitive to extremes of pH and to concentrations of carbonate and bicarbonate (Lagler, 1966).
The pike young grow at a rapid pace. The fastest growing fish may achieve a length of 44.6 cm and a weight of 460g by mid-October. The faster growing fish are those that first make the shift to a fish diet, and they are most likely to become cannibals.
Pike appear to require less food for maintenance than most fish and are therefore able to convert a relatively large portion of their food into growth. This then makes the pike well adapted to withstand long periods of starvation. Adult pike feed almost exclusively on fish; the kind consumed depends upon what ever is available. Other organisms included in the diet are waterfowl, frogs, small mammals, such as mice and shrews, crayfish and insects. In general, pike seem to eat whatever they can catch and swallow, but their favorite food is the coho (Rutz, 2000). Digestion of fish is fairly rapid at 50% complete digestion in 20 hours. Birds, on the other hand, require a much longer time to digest, almost 130 hours for 50% digestion due to feathers.
Fish and Game Plan
The first action the Alaska Department of Fish and Game wants to take is to get public opinion about any fish-related topic. Because they are a public-service institution, they need to find out how the public wants them to handle each problem. As far as the pike invasion is concerned, if the public doesn't want pike in the Anchorage lakes, Fish and Game will choose the best possible way to get rid of them. If the public wants pike to stay in the lakes, then they will leave the lakes alone. As of January, 2000, pike have been confirmed in Sand, Taku Campbell, Cheney, Lower Fire, and Gwen Lakes as well as Campbell Creek (See Appendix iii). Pike have been reported, but not confirmed in Mirror and Delong lakes and Ship Creek.
ADF&G biologists are working to get tougher laws against illegal stocking, and enforcement and prosecution of persons engaged in illegal stocking of non-native fish into bodies of water (Stratton, 2000).
The public process Fish and Game uses, is to educate the public with the pertinent facts, and then solicit solutions. The biologists at ADF&G plan to start this process soon. Some possible solutions they have in mind are using Rotenone on the Anchorage lakes, depleting the oxygen levels of the lakes, bounties, snagging and/or derbies.
Using Rotenone in the lakes is one of the major plans Fish and Game is considering. Rotenone is a natural substance, made from ground up roots. It has been proven effective on a lake in Kenai, now called Perch Lake (apparently, someone had illegally stocked the lake with Yellow Perch). It works by preventing anything with gills from taking in oxygen (Finlayson, et al. 2000). It poses no known threat to humans, other animals, or the environment, according to Fish and Game officials.
As of November 2000, there has been a Moratorium on the use Rotenone. It had been used in Alaska since the 1960's and 1970's, but recently there was thought to be a connection between Rotenone and Parkinson's disease. Fish and Game doesn't believe there is a problem, because it would take a large dose of Rotenone injected directly into the blood to seriously affect any organism. This was actually done to rats in the Parkinson's research (Stratton, 2000). Rotenone is the same substance that is used on vegetables and fruits in our grocery stores, yet there hasn't been a proven connection to cause any disease. There are also no known mutations or problems in human genes from Rotenone. Fish and Game are expecting the Moratorium to be lifted next spring.
An alternative plan to Rotenone is depleting the oxygen in the lakes. When the lakes freeze over, they will take dissolved oxygen readings, and then put oxygen into the lakes using an air compressor and pumps, causing the layers with oxygen to mix with layers without oxygen, which will lower the overall oxygen level, causing the fish to suffocate. To do this will require some equipment that is reusable, making it cheaper in the long run than using Rotenone.
The other plans such as derbies, bounties, and snagging are most likely not going to happen. ADF&G has already stopped stocking Anchorage area lakes because they don't want to feed the pike (Stratton, 2000). A derby could take place for a few years, but the fear is that people will lose interest with the expected quickly declining fish populations. When the pike numbers rise again, Fish and Game will be required to kill them anyway to save the native species. All these solutions cost money, and, as of now, there is 0 funding for the pike plague.
The first thing we must consider before taking action against the Northern Pike is whether the people of Alaska want the pike eliminated. The Dimond High School (DHS) NOSB team is prepared to help ADG&F conduct a survey to solicit public opinion on the destiny of the pike. People enjoy fishing for them because they are great fighters, making them fun to catch. Even though they are such aggressive predators, we feel that public opinion would be against poisoning the lakes for many reasons. The DHS plan is to consider utilizing the aggressive nature of these fish to help monitor, control, and/or eliminate them from our Anchorage lakes and streams.
The first idea is to promote a pike derby to take place on the summer solstice. There is already some celebration that occurs on that day, and adding a fishing derby would bring out more residents and tourists to participate in a variety of activities. The derby would include fishing for pike with prizes offered, recipe contests for preparing pike, eventually the sale of a pike cookbook, ADF&G biologists and others offering educational fisheries information, and a variety of vendors with food and fun activities. We propose to call this celebration "Pike Day".
People taking part in the fishing derby would meet at a central location (derby headquarters) between the lakes inhabited by the pike. They would buy tickets and receive the rules, then fish for 24 hours in any of the lakes invaded by pike. So far, pike have been caught in Cheney, Taku Campbell, Otter, Sand, Fire, Delong, and Gwen Lakes, and Campbell and Ship Creeks, according to Dan Bosch (pers. comm.). At the end of the 24-hour derby, prizes would be awarded for the biggest, smallest, ugliest, first and last fish caught, with the grand prize going to the person who caught the most fish! We think that a festival is exactly what Alaskans would support to deal with the pike plague. So many times Alaskans feel left out of fisheries management, and the opportunity to participate, educate, and have fun seems appropriate.
If the derby is successful, and the pike populations decrease, the annual derby could be used to monitor the status of the pike in area lakes. With the help of the public, ADF&G would be able to significantly lower the population of pike, monitor their status annually, satisfy both anglers and environmentalists, and raise funds in the process. Seems like a win-win situation to us!
Another possible solution is to fence any lakes outlets so that the fish would be trapped and eventually eat everything in the surrounding area including themselves. The positive aspect about this particular idea is that it does not use poison that may cause harm to other organisms in the vicinity. The drawback is that not only would we trap the pike, but anything else that could not fit through the fence.
The third idea that came to mind was to use lime (CaCO3) to raise the pH level. Young pike are extremely sensitive to pH level changes (Lagler, 1966) while salmon can tolerate a slightly higher pH. But this could be like a poison affecting more organisms than the pike. While trying to eliminate an invasive species, we must always keep in mind that an ecosystem is a very fragile thing, and once disrupted can be crippled for a long period of time.
The last idea would be to remove the vegetation close to the shore where pike like to live. The drawback to this idea is that other animals find this habitat just as inviting as pike. Also, removing vegetation removes the roots that hold the banks together causing erosion and eventually more damage to the ecosystem.
There are and always will be a drawback in eliminating a species. That is why we must take every precaution and analyze every idea in choosing which way to go. We suggest the following steps:
Periodic monitoring will be required because there is no sure way to regulate and enforce invasive species policies in an ecosystem as vast as Alaska.
Funding and Socioeconomic Impact of Plan
One possible way that the pike problem could be solved is by having a fishing derby on the summer solstice. Our suggestion of a "Pike Day" derby would generate funds to use in the management of this invasive species. In this derby, adults would pay $15; young adults would pay $10, and children 12 and under would pay $5. There would be prize categories for each age group, with prizes donated by the Anchorage Chamber of Commerce, local businesses, and private citizens. The goal, of course, would be to over fish the pike from Anchorage area lakes and streams and have fun. If there were at least 2000-3000 of the 30,000 freshwater anglers (ADF&G Harvest Report, 2000) attending the festivities and participating in the derby, there would be a minimum of $23,750 raised from entrance fees alone (see Appendix ii). The derby would be over the course of 24 hours with most of the activities taking place at a central location, possibly Cheney Lake. It has been suggested that Taku Campbell be used as a control lake to help demonstrate the impact of the derby on the pike populations (Sugai, 2001). A variety of vendors could set up shop to provide food and drink, arts and crafts, information, etc. at all the lakes infested with pike. A portion of their proceeds would be collected for funding pike management.
By combining summer solstice and "Pike Day," the crowd could be enormous in size. Anchorage currently has a population of 267,000 with an estimated increase to 367,000 by the year 2020 (http://www.muni.org.). We think that 2000-3000 participants is a number that can be easily met and probably exceeded. Considering that a great number of the tourists that come to Alaska come just to fish, they will most likely want to participate in the activity, also. With a festive, carnival-like atmosphere, residents and tourists of all ages and interests would be attracted to the event year after year.
On the first "Pike Day", there would be a contest for the best pike recipes (see Appendix iii). Some recipes can be found on ADF&G's pike page on the internet (http://www.sf.adfg.state.ak.us/region2/areas/anch/anch/html/pikepage.stm). At future "Pike Day" derbies, a Pike Cookbook would be offered for sale that contained all the recipes offered for cooking pike. If the cookbook were offered for sale at $10 each, and 1000 copies were sold, $10,000 would be raised for pike management.
The Alaska Department of Fish and Game currently has no money in their budget designated for the pike problem in the Anchorage bowl. However, there is some money set aside for the removal of species that are not native to these waters. The ADF&G is soliciting the Alaska Legislature to approve the Invasive Species Act for Alaska, and will ask for a $100,000 budget for implementation, enforcement, and monitoring of this law. The public funds generated by "Pike Day" activities would certainly bolster this budget.
The problem with pike in Anchorage lakes and streams is a major concern to biologists and local residents. Pike are vicious, large, and ugly creatures that will eat everything that comes into their path. This is a real concern because pike love salmon fry, especially coho. We already have a decline in the coho populations, and they could suffer irreparable harm if the pike is allowed to flourish in the Anchorage area. All species native to these lakes will eventually be wiped out if pike are allowed to stay. This hurts all of the residents and tourists that like to fish, and the people who fish for a living. So, the general consensus is that the pike must go. What we don't agree on is how to eliminate them.
The ADF&G plan is to use Rotenone as soon as the moratorium is lifted. They have already stopped stocking area lakes and streams with salmon and trout. Barry Stratton has also suggested deoxygenating the water by pumping air into the lake under the ice, mixing the oxygen evenly throughout the lakes, suffocating all gilled organisms. Even though these measures would work, public education, stronger laws and better enforcement, along with continuous monitoring are the only way to keep pike out.
Our suggested plan utilizes some of the ideas put forth by ADF&G, but does not include the use of Rotenone. More research is needed to prove its safety before we could sanction its use. As citizens, we suggest a measure that treats the ecosystem more gently, involves the public in a greater way than they would normally be allowed to participate, and generates funds without a tax increase.
Van Ryn, Cameron. February 4, 1999. Pike: Predator or trophy. Alaska Star, 11-14.
Finlayson, B.J., R.A. Schnick, R.L. Cailteux, L. DeMong, W.D. Horton, W. McClay, C.W. Thompson, and G.J. Tichacek. 2000. Rotenone use in fisheries management: administrative and technical guidelines manual. American Fisheries Society, Bethesda, Maryland.
Lagler, Karl. Freshwater Fishery Biology Dubuque: W. C. Brown Company, 1966.
Morrow, James. The Freshwater Fishes of Alaska Anchorage: Alaska Northwest Publishing Company, 1980.
Bosch, Dan. Alaska Department of Fish and Game, 907-267-2153, 2000.
Stratton, Barry. Alaska Department of Fish and Game, 907-269-2398, 2000.
Alaska Department of Fish and Game; northern pike. firstname.lastname@example.org. 12/6/00.
Alaska Department of Fish and Game; pikepage. http://www.sf.adfg.state.ak.us/region2/areas/anch/html/pikepage.stm. 12/7/00.
Anchorage Municipality Homepage; demographics. http://www.muni.org. 12/8/00.
Sugai, Susan, P.H.D. University of Alaska-Fairbanks, Alaska Sea Grant Program. January, 2000.
Alaska Fish and Game Laws and Regulations
Annotated 2000-2001 Edition
5 AAC 75.055. POSSESSION OR MARKING OF LIVE FISH OR LIVE FISH EGGS. It is unlawful to possess, transport, and release live fish or live fish eggs, or in any way mark any live fish before release, except in accordance with the terms of a permit issued by the commissioner under 5 AAC 41 or AS 16.05.930(a). (In effect before 1985; am 5/31/85, Register 94)
* Northern pike confirmed in all lakes but Delong, and ADF & G suspended the stocking of the confirmed lakes.