Malheur National Wildlife Refuge
Pacific Region

Aquatic Health

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Malheur Lake Work Group

In January 2014, the Malheur Lake Work Group met to determine how to systematically tackle improving aquatic health on Malheur Lake. Please see the notes from the work group and the one page projects that were identified as the top priorities. Priorities for the Work Group are components of the Refuge's Inventory and Monitoring Plan.

2014 Meeting Notes

2014 Project Priorities

Fisheries Biologist, Linda Beck presented a poster at the 2012 American Fisheries Society annual meeting about aquatic health work on the refuge. View her poster.

The Refuge's mission is to conserve wildlife and habitat for the American Public and generations to come. The primary focus of the Refuge has been the management of habitat for 320 species of birds and 58 mammals; fish habitat has become an important aspect of the habitat management program. The Refuge is now placing special emphasis on the management of native fish species found within the Blitzen River watershed.

To develop an effective aquatic health program for the Refuge, we must understand how fish use our waterways; the timing of migration of redband trout and other native fish; identify all native fish spawning areas; understand population dynamics; and fish densities. The biggest challenge for the program will be to understand the impacts that invasive common carp (Cyprinus carpio) have on aquatic health and how this relates to bird use on the refuge and Impacts to wetlands and ponds.

The greatest impact of carp on wetlands is their feeding behavior. Carp are bottom feeders and sift through mud searching for aquatic insects and plants. Feeding activities not only uproot aquatic vegetation, but also produce silt plumes in the water column which makes it difficult for plant synthesis and insect production. Carp in the 15 pound range are not uncommon in Malheur Lake and other water bodies of the refuge.

To learn more about carp and aquatic health on the refuge we have prepared a white paper which contains more information. A Harney Basin Wetlands Initiative is also moving forward and invasive common carp are a major focus of this group.

Check out a recent article - The Harney Basin Revival: The Role of Carp Wrangling and Consensus Building by Bruce Taylor, Oregon Habitat Joint Venture, in the Intermountain West Joint Venture newsletter about carp efforts in the Harney Basin. This informative article provides links to other activities happening in the Harney Basin.

Sampling Invasive Carp in Mud Lake

A net full of carp removed from Mud Lake
weighing carp
fisheries staff check the water quality of mud lake
Over 100 invasive carp are trapped in a trammel net in Mud Lake Invasive carp are measured and weighed before tissue samples are removed for bacterial analyses Water quality is recorded before removing a net full of invasive carp

Surgery has Gone to the Fishes at Malheur Refuge

Volunteers and staff at Malheur Refuge have been braving the blustery spring weather to capture and implant radio tags in invasive common carp. Twenty radio tags purchased by the Oregon Wildlife Heritage Foundation (OWHF) were surgically implanted in carp at Boca Lake on the refuge over the last few weeks. OWHF donated $4,000 for the purchase of the radio tags which will last for two years. The Harney County Veterinary Clinic donated sterile sutures to be used during the surgical procedures. Each radio tag has a unique frequency which allows tracking of individual carp movements. The carp are captured alive, anesthetized, have the radios surgically implanted in them and then are revived and released back into the lake.

Invasive common carp are removed from a net prior to having a radio tag implanted
Fisheries biologists remove invasive common carp from a net prior to implanting radio tags for telemetry tracking studies.

The radio telemetry project is part of a larger Harney Basin study which will analyze the impacts of invasive carp on area wetlands. Invasive carp are bottom feeders and their activities cause mud to rise in the water column. When this happens sunlight cannot filter down through the water to stimulate plant growth. Waterfowl and other native fish depend on abundant plant growth in wetlands for feeding, nesting and spawning. When carp populations become too large they literally eat themselves out of house and home by eliminating all plant growth and they turn lush wetlands into wastelands. This not only impacts resident birds and fish, but it has a significant impact on migratory birds passing through the Harney Basin on their way to northern nesting grounds. A reduction in quality wetlands elsewhere in the Pacific Flyway means that Harney Basin wetlands are nationally important for migratory birds.


Refuge volunteer holds a seven pound carp which will be implanted with a radio tag
Radio telemetry tag is surgically implanted in a carp
Refuge Volunteer Marilyn Kircus assists with surgery to implant a radio telemetry tag in a seven pound invasive common carp. Fisheries Biologist Linda Beck implants a radio telemetery tag in an invasive common carp before releasing it.

Boca Lake carp were chosen for the study to provide a controlled research environment to determine carp movements and to explore potential capture techniques to remove large numbers of fish. Twice a month for two years Refuge Fisheries Biologists will track each of the tagged fish to identify their location. GPS coordinates will be used to build maps of population densities; to determine if the carp have seasonal preferences for congregating; where they feed at different times of the year; and where they are spawning. These maps will then be used to decide on methods to decrease the number of carp in wetlands and possibly to eliminate carp. Research elsewhere in the Great Basin indicates that carp often come together in large groups in the winter, if this also occurs in the Harney Basin it would make it easier to capture large numbers of carp. Researchers involved in the project include Oregon Department of Fish and Wildlife, Ducks Unlimited, the University of Minnesota, the Natural Resource Conservation Service, Harney Basin Soil and Water Conservation District, Malheur Wildlife Associates and the US Geological Survey.

The Oregon Wildlife Heritage Foundation has expressed interest in helping to raise private funds for carp control in the Harney Basin. The Foundation was established in 1981 to receive money for and provide funding to beneficial fish, wildlife, and habitat projects throughout Oregon. Over the last 30 years, the Foundation has directed over $15 million dollars in monetary support to hundreds of fish and wildlife-related projects.

Aquatic Health Coalition List Serve

In November of 2009, a list serve to relay pertinent information to interested people about invasive carp and Refuge activities was established. Today the coalition is over 100 people strong. To receive information from the list serve please sign up here.

2012 and 2010 Aquatic Health Workshop Summary Notes

The Refuge has hosted two Aquatic Health workshops to bring leading researchers, biologists and partners together to review research results and to plan invasive carp management strategies.

The Refuge hosted the second Aquatic Health Workshop on March 13-14, 2012. Sixty participants over two days talked of what has happened since the March 2010 Carp workshop and what direction the Refuge will take in the future. Click here to read the 2012 meeting summary notes. Presentations presented at the workshop can be downloaded from the Refuge's FTP Site.

During the 2010 Invasive Carp workshop, participants wanted to change the direction of the group to focus on Aquatic Health issues and not just invasive carp. A product of the workshop was a complex model designed by Iowa State University PhD. Student Mike Colvin. To view this model click here. Click here to read the 2010 meeting summary notes.

Last updated: September 24, 2014