State to use fish pesticide in Sucker Lake to kill invasive pike

The Alaska Department of Fish and Game will apply a fish pesticide to two lobes of Sucker Lake in August 2026 as part of ongoing efforts to suppress invasive northern pike in the Alexander Creek drainage.

Staff will apply Rotenone to Sucker North and Sucker West to remove as many northern pike as possible, according to a May 11, 2026, press release from the department. Sucker South will not be treated but will be gillnetted in late fall. All lobes will receive netting effort in subsequent years.

The department has been conducting invasive northern pike suppression in Alexander Creek since 2011. To date, this work has been limited to the side sloughs along the creek during the month of May. Beginning in August 2026, suppression efforts will be expanding into Sucker Lake.

Beginning in spring 2027, netting will be conducted in Alexander Lake.

The department has completed over 25 rotenone treatments for northern pike eradication since 2008. Such projects typically take one to four years to complete.

Northern pike are invasive predators in Southcentral Alaska, where they do not naturally occur. The fish threaten native salmon and trout populations. Northern pike were first introduced to Bulchitna Lake in the Yentna River drainage in the Susitna River basin in the late 1950s. Since 2011, it has been illegal to release northern pike alive in the Susitna River drainage and West Cook Inlet area waters. Since 2020, it has been illegal to release northern pike alive in any Southcentral Alaska waters. Invasive northern pike have been found in over 150 lakes and rivers in Southcentral Alaska, according to the department's 2022-2030 management plan.

Over $8 million has been allocated to invasive northern pike eradication, suppression, and monitoring in Southcentral Alaska to date, according to the management plan. Recreational fisheries contribute approximately $1.4 billion to Alaska's economy. Seventy-five percent of that value occurs where northern pike are invasive.

Rotenone is a naturally derived piscicide used by the department for complete eradication of invasive fish. The department said draining and chemical treatment are the only proven methods for eradication.

The Alaska Department of Natural Resources Division of Agriculture will also be conducting work on invasive Elodea in the Alexander Creek drainage from 2026 through at least 2027. Elodea is Alaska's only known aquatic invasive plant.

Elodea was discovered in Alexander Lake in 2014 and spread to Sucker Lake in 2016. The Department of Natural Resources has been conducting treatments to eradicate Elodea in these two lakes since 2019. Treatments will resume in mid-June in both Alexander Lake and Sucker Lake and will occur several times through August.

Treatments have resulted in excellent progress. Full eradication is the goal in both lake systems, according to the press release.

Elodea can become entangled on plane rudders and boat propellers. One small fragment of the plant can set roots and establish new infestations in other waterbodies. Additionally, activities causing the plant to fragment would negate treatment efforts.

Because of this, both the Department of Natural Resources and the Department of Fish and Game recommend people minimize activity at Alexander and Sucker Lakes from May 15 through Sept. 15, 2026, and from May 15 through Sept. 15, 2027.

To report an invasive species, use the online reporter at https://www.adfg.alaska.gov/index.cfm?adfg=invasivespeciesreporter.main or call 1-877-INVASIV.