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Balancing Sea Lamprey Control Treatments and the Surrounding Ecosystem
Midwest Region, May 21, 2014
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Gastric lavage performed on a brook trout.
Gastric lavage performed on a brook trout. - Photo Credit: Mary Henson
Stomach contents from gastric lavage sampling of a brook trout.
Stomach contents from gastric lavage sampling of a brook trout. - Photo Credit: Gregg Baldwin
Hester-Dendy multi-plate samplers.
Hester-Dendy multi-plate samplers. - Photo Credit: Cheryl Kaye
Hester-Dendy multi-plate samplers placed in the stream.
Hester-Dendy multi-plate samplers placed in the stream. - Photo Credit: Cheryl Kaye

 

The Problem: In 2009, the Hiawatha Sportsman’s Club in Engadine, Michigan contacted the Sea Lamprey Control Program with concern that sea lamprey lampricide treatments were negatively impacting the aquatic invertebrates. In particular, the Club was concerned about a potential decline in burrowing mayflies which would result in a reduction of fish in Cold Creek, a tributary of the Millecoquins River in Mackinac County, Michigan. Resolution of this concern was needed to ensure that the Club would grant the Program permission to access and treat Cold Creek.

Without sea lamprey control treatments, the Millecoquins River system would contribute a substantial number of sea lampreys which prey on fish in Lake Michigan. Treatment of the system is an important piece in controlling the sea lamprey population in the lake. The Club owns 35,000 acres of land and a large portion of the Millecoquins River system flows through their property. Access permission is needed to treat the upper and lower Millecoquins River and Cold Creek.

Solving the Issue:  The Program embarked on a study to determine whether sea lamprey control treatments were affecting the aquatic invertebrate population in Cold Creek. This information would provide all parties with a better understanding of the impacts of treatments on non-target species of concern. 

The Sea Lamprey Control Program regularly takes steps to reduce the effects of sea lamprey treatments and program operations on non-target species. The primary method used to control sea lamprey in the Great Lakes is the application of lampricide. Lampricide is applied to streams to remove sea lampreys during their larval stage of the life cycle. Often times, these treatments are amplified with a formulation of what is called Bayluscide. Bayluscide helps to increase the toxicity of lampricide to sea lampreys, and allows the control team to use less lampricide. When used in the appropriate amounts, these treatments are estimated to eliminate about 95% of sea lamprey larvae in treated areas.

Alternative methods used to control populations include barriers to block and traps to capture spawning adults. These operations have the potential to affect non-target organisms and the Program takes care to minimize potential  mortality by implementing special procedures where other sensitive species may be encountered.

The study: To address the Club’s concerns, the Program conducted a study to: 1) assess the presence of burrowing mayflies and their habitat; 2) assess the effect that lampricide exposure had on aquatic invertebrate populations; and 3) determine the diet composition of resident fish before, during, and after the lampricide and whether exposure to the treatments affected their ability to forage.

Results: The study demonstrated that no burrowing mayflies were in the mainstream of Cold Creek. The substrate in the stream consists mostly of sand bottom with woody debris which is not preferred habitat of burrowing mayflies.

While burrowing mayflies were not present in the stream, a total of 58 other aquatic invertebrate species were collected and identified in the study’s sampling units. The study found that the treatment of Cold Creek did not result in a reduction of any aquatic invertebrates. However, there was a difference following the treatment in two invertebrates, a type of mayfly and the stonecase caddisfly but not in the treated area of the stream. In both cases, the density of the species decreased in the untreated area, while they either increased (mayfly) or stayed the same (stonecase caddisfly) in the treated area.

The study showed that a lampricide treatment can affect the feeding behavior of opportunistic brook and rainbow trout. Comparison of stomach contents showed that the number of aquatic invertebrates consumed by the fish during the treatment increased by 40%. The fish temporarily abandoned their normal food items in favor of a drifting fingernet caddisfly that spins fine-meshed nets on the underside of rocks where they are usually unavailable as food for fish. One week following the treatment, stomach contents of fish in Cold Creek were similar to the pre-treatment period.

The verdict: The study was successful in demonstrating that lampricide treatments do not negatively affect the invertebrate or fish populations in Cold Creek. By conducting this work, the Program was able to reach an agreement on access permission with the Club that will continue to provide for the safe and effective removal of larval sea lampreys from the Millecoquins system and protect Lake Michigan.

 

 

By: Cheryl Kaye 


Contact Info: Mary Wilson, 906-226-6571 Ext.1207, mary_wilson@fws.gov



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