Purpose of the project:
Approximately 50 air miles northwest of Anchorage, Alexander Creek Watershed is a remote and slow-moving meandering river system with numerous tributaries and shallow lakes and ponds. It has thousands of acres of adjacent wetlands with side-sloughs and oxbow channels. Originally named a Waters to Watch project in 2015, we are looking at this project in retrospect as elodea continues to be an issue affecting the habitat for Salmon in the lake and returns to the Susitna River.
In the late 1990s Alexander Watershed was highly productive Chinook and coho salmon habitat, and arguably the premier Chinook sport fishing area in the Matanuska-Sustina Valley (Mat-Su). It supported what was likely a multi-million dollar salmon fishery with lodges, daily flight service, and boat charters. Today, however, due to low returns, Alexander drainage is closed to Chinook harvest and is a fraction of the economic driver it once was. Anglers today are motivated to travel to the remote lake to catch invasive northern pike, rather than salmon.
While northern pike (Esox lucius) are native north and west of the Alaska Range in interior Alaska, they are an introduced species to the Mat-Su Basin (thought to have been introduced illegally in the early 1960s), where they are voracious predators of juvenile salmon and other native resident fish and wildlife. Impacts of invasive northern pike predation on native fish populations are known to be devastating where their habitats overlap. Northern pike prefer cool, slow-moving shallow waters that are highly vegetated, enabling them to hide and ambush prey. The potential threat of northern pike is greatest for Chinook and Coho salmon due to a preference for similar habitats. To date, pike have expanded throughout the entirety of the Alexander drainage resulting in native fish populations that contribute to eroding subsistence, commercial and particularly sport fishing opportunities. Northern pike have direct impacts on salmon populations, and indirect economic impacts on ecosystem health through decreasing biodiversity, removing salmon as a food source for terrestrial predators like bears and eagles and reducing the transfer of marine-derived nutrients to terrestrial ecosystems through decaying salmon carcasses.
Compounding the situation, in August of 2014, the aquatic invasive plant Elodea was discovered for the first time in Mat-Su waters by Alaska Department of Fish and Game crews suppressing and monitoring northern pike. The relatively small, patchy 10-acre infestation in Alexander Lake is thought to have established from a transported fragment via floatplane from Sand Lake; the only Anchorage infestation that allowed floatplane traffic at the time. Of the 20 total waterbodies with Elodea discovered in the entire state of Alaska, Alexander is one of the few recent discoveries in a remote location.
When introduced to a new waterway, Elodea grows rapidly, overtaking native plants, filling the water column, and changing the habitat conditions to which native fish are adapted. Thick mats form at or just below the water surface and can foul boat propellers and floatplane rudders, causing a hazard and greatly increasing the potential for spread. In addition to impeding fishing, navigation, boat launching, and paddling, it can also reduce waterfront property values. In Alaska’s environments ranging from Fairbanks to Cordova, it tolerates cold winters and photosynthesizes under the ice. Unfortunately, since the discovery of elodea in 2014, it has already established throughout 90% of Alexander Lake and fully covers the Sucker Lake complex.
Further, it is expanding downstream in Alexander and Sucker creeks. This habitat change may now be creating better habitat for predatory northern pike, further exacerbating the existing impacts of pike predation on juvenile salmon and other fish.
Human Interest/Community Benefit:
Partners have been working to restore Alexander Creek drainage Chinook salmon numbers in what previously was very productive habitat, and one of the most vibrant Chinook sport fisheries in Southcentral Alaska. This abundant fishery attracted international, national and in-state anglers supported with lodges, daily flight service, and charter boats, providing a boost to the local economy.
With the recent increase in the Elodea infestations, there is a concern of compounded effects of pike and Elodea on salmon that will not only reduce gains made in reducing pike populations by partners but increase the challenges already faced by Chinook salmon populations returning in lower numbers to the Susitna drainage. This is particularly significant during a time of general statewide Chinook declines, where 8 of the 14 statewide stocks of concern are located in the Mat-Su. 8 of these stocks – one of them being Alexander Creek, are Chinook stocks from the Susitna drainage, and 1 is a sockeye stock.
The greatest threats to salmon and salmon habitat in the Mat-Su are typically due to human development impacts. Invasive aquatic species like Elodea and pike pose a threat to remote areas as well. With concurrent, Chinook salmon declines across the state, Alexander Creek drainage and the excellent salmon habitat it provides is increasingly important.
Project Timeline:
Mat-Su salmon habitat partners continue to plan and implement ongoing efforts to suppress pike and survey high-risk waterbodies, educate and eradicate Elodea in Alexander Creek drainage.
Partners:
Alaska Department of Fish and Game (ADF&G) – ADF&G has completed the 9th year of a long- term and large scale annual gillnetting project to control northern pike on Alexander Creek. The intent is to replenish depleted anadromous and resident fish populations and restoring sport fishing opportunities to this once very popular and productive system. As part of the project, ADF&G also conducted a radio telemetry study to investigate movement patterns between Alexander Lake and the mainstem of the creek, is investigating diet, and testing effective control and detection methods. Directed by the Management Plan for Invasive Northern Pike and prioritized through a strategic planning process, the northern pike suppression project in Alexander Creek is the largest of its kind ever attempted in Alaska, and preliminary findings from the nine years of this project are encouraging.
Project goals are to create an annual, large scale pike removal protocol on side channel sloughs to remove as many pike as possible, track spatial and temporal movement trends of pike to and from Alexander Lake, and measure success, monitor adult salmon returns, resident fish production and juvenile production and movement.
As of spring 2019, results have been very successful. With each year of pike suppression, Chinook fry were found further up the creek system and now occupy the entire 40-mile river corridor again. Unfortunately, the movement patterns observed during the telemetry study are now likely being influenced by the extensive growth of Elodea in the system.
Cook Inlet Aquaculture Association (CIAA) – Continuing long term pike suppression efforts in 2019 on adjacent watersheds on the Susitna River that additionally includes the examination of seasonal movement patterns, population estimates, and field testing of electronic fish barriers.
Although the Mat-Su is the fastest-growing region in Alaska, putting increased pressure on the spread of Elodea, much of the Mat-Su is remote and in many cases most readily accessed only by boat or floatplane. Alaska’s biggest population center - Anchorage is adjacent and regularly utilizes Mat-Su’s rich resources to fish, hunt and recreate. Many Alaskan’s fly private aircraft, and there are several lakes currently infested with Elodea that see significant floatplane and motorboat use, vectors that could easily lead to further spread of Elodea. Even a tiny fragment that hitchhikes on boats, trailers, floatplane rudders or other gear can establish a new infestation in another waterbody. The Alexander and Sucker Lakes Elodea was very likely spread by floatplane from one of the Anchorage infested lakes. For this reason, Elodea outreach, detection, and eradication efforts are broader and more regional in scale and by necessity extend outside the Alexander Creek and Mat-Su Basins.
Partners are currently are working on eradication plans for Alexander Creek Watershed. To date, all herbicide permits have been acquired and a NEPA study has been concluded. An Outcome from a Mat-Su Salmon Partnership site visit, a broad-based Elodea Task Force formed to help implement all aspects of elodea control and eradication work, and ADF&G has temporarily closed sport fishing in Alexander and Sucker Lakes to help contain the Elodea and prevent dispersal from floatplanes accessing those lakes. Funding remains a challenge for this work. However, partners will be sampling high priority areas in the Mat-Su, educating priority audiences like pilots, residents of infested lakes, anglers and guides and will be providing training to help build awareness and create a growing body of residents, recreationists and practitioners who all can recognize Elodea and know what to do if they do see it. Efforts to fundraise for the project are on-going, and herbicide treatments in the watershed will continue. The Mat-Su Salmon Partnership is working with DNR to develop and help support further future training opportunities as well as implement an Elodea statewide management plan.
Alaska Department of Natural Resources (ADNR) (NFHP FY19 funding) – lead agency and currently working with partners on an eradication plan. Anchorage infestations are scheduled to be nearing completion in the summer of 2019. Because the infestation in the Mat-Su is so significant and a high concern for dispersal, ADNR along with other collaborating partners, are making Mat-Su Elodea eradication in the Alexander Creek Watershed the highest priority.
Tyonek Tribal Conservation District (TTCD) – TTCD continues to conduct a district-wide invasive plant survey covering Alexander Creek, Beluga, and Skwentna as well as rivers and roads not previously surveyed.
Cook Inlet Aquaculture Association (CIAA) (NFHP funded) – surveyed Susitna River watershed lakes in 2018 and continues to plan further surveys in 2019.
Alaska Department of Fish and Game (ADF&G) – Closed sport fishing in Alexander and Sucker Lakes in 2019 to help contain the Elodea. Continues to assist with herbicide treatment planning, project implementation, and fundraising. Several field staff crew and project managers have taken Aquatic Invasive Species training that includes information on how to identify, survey for, and recognize habitat for Elodea. Alexander pike suppression field staff are collaborating with ADNR for sample taking and logistics for Elodea eradication project.
U.S. Fish & Wildlife Service (FWS) - Providing outreach, funding, and technical support for Elodea early detection and rapid response efforts in Mat-Su, Kenai, Anchorage, and Fairbanks.