While the Malheur National Wildlife Refuge (MNWR) continues its efforts to control carp, it is also focusing on the overall aquatic health of the environment and studying key indicators of environmental conditions, such as the Columbia spotted frog and mussels.
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Studies under way on several refuge species
by Randy Parks
In late May, the mechanized fish trap and sorting facility was completed at the Sodhouse dam, funded by Oregon Wildlife, Friends of the Malheur National Wildlife Refuge and the refuge.
Fish swimming upstream for spawning enter the enclosure through a narrow passage, where they become trapped. The trap is then lifted out of the water by an electrical hoist, and the fish are flushed through a “water park-like” tube into a holding tank, and out on to a sorting table. The carp are put into one holding tank, while the desirable species are placed in another to be returned to the refuge water.
The Sodhouse dam is one of five dams in the refuge’s system, four of them equipped with fish traps.
Since early spring, the refuge has removed about 28,000 carp from the Sodhouse dam trap. They are then distributed as fertilizer, crayfish bait, or disposed of.
Fish biologist Linda Beck said the refuge staff conducted studies this spring looking at carp egg predation. They tested six species of refuge resident fish to see if they were feeding on carp eggs. Findings showed that black bullhead, tui chub and dace all made carp eggs a part of their diet.
Another study was done to see which, if any, resident fish fed on carp larvae, and that study was inconclusive.
In 2012, the Army Corps of Engineers constructed a nesting island for migrating terns on Malheur Lake with the intention of decreasing the population on East Sand Island in the Columbia River that feed on threatened and endangered salmon. A bonus to the refuge is having the terns feed on carp.
The Corps funded Oregon Department of Fish and Wildlife (ODFW) Native Fish Division to see if the terns are impacting the redband trout population of the refuge. ODFW is now in its first year of research. Redband trout have been identified as a sensitive species in the state, and the Malheur Lake Basin has about 44 percent of the entire Great Basin redband population.
The trout travel 40 to 50 miles upstream to spawn each year, and to track them, the ODFW inserted passive integrated transponders (PIT tags) into the fish. Several PIT-tag monitoring systems, powered by solar panels, are positioned around the refuge, and when one of the tagged fish passes by, the data is automatically recorded.
The data will be used to track the year-round movement of the trout, as well as assess the passability of dams, fish ladders and other structures in the Blitzen River.
Columbia spotted frogs
Herpetologist Chris Rombough is one-and-a-half years into a two-year study of the distribution and life history of the Columbia spotted frog on the refuge.
His study is a component of the carp project, with the objective of gathering baseline data on the presence and distribution of the frog on the refuge.
Rombough explained that amphibians are cold-blooded and don’t range very far in their environment, so they are a good indicator of the environmental conditions. By collecting and understanding baseline data, Rombough hopes to be able to predict what would happen to the species under the carp management plan and changes in habitat conditions.
The study includes the frog’s habitat, breeding patterns, growth rate, transformation and its role in the ecosystem.
The main challenges for Rombaugh are the vast size of the refuge, 187,000 acres, and the complexity of the water system. “There are multiple inputs into the basin, and it’s not consistent every year,” Rombough said. “But it’s my job to find the clues and come up with an answer.”
The Columbia spotted frog is considered “sensitive”and is an extremely aquatic species. Most of its life is spent in the water and has adapted accordingly. Its legs are shorter for more thrust in the water, and its webbing between the toes is more prevalent than in other species. Its eyes are located more toward the top of its head to allow more visibility while floating in water and it has the ability to feed underwater.
Using a science-based approach, the refuge will have the ability to predict a species’ future depending on the action of a management plan rather than implementing a plan and try to fix any ill effects it might have.
Mussels are another key indicator of aquatic health because of their sensitivity to any bad water quality.
One unique aspect of the mussels at the refuge is that there have been four species identified: the California floater, the Western ridged, the Western pearlshell and the winged floater.
Heading south down the road from the Sodhouse dam, aquatic health technician Kris Crowley stopped at a couple bridges to check for mussels.
At the first stop, the water was a bit turbid, and the mussel search was a little stark.
The second stop was more productive, with clear water providing better conditions. Crowley also pointed out more aquatic plants in the area, suggesting less carp population. Without the carp stirring up the water, more sunlight passes through the water, allowing more vegetation to grow.
Bodeen bids farewell
After a little more than four years as Refuge Manager, Tim Bodeen’s last day in the position was Thursday, August 1.
Bodeen accepted the manager’s position at the Minnesota Valley National Wildlife Refuge, located just outside the Twin Cities.
During his time at the MNWR, Bodeen worked on the invasive carp program and improving aquatic health, spearheaded the 15-year Comprehensive Conservation Plan, set aside funds for historic buildings at Sod House Ranch, oversaw improvements at refuge headquarters and helped with building a strong visitors service.
His replacement has yet to be named.
The refuge is looking for volunteers to walk waters and help rid the refuge of carp.
They are also looking for volunteers in the spring to operate the Sodhouse Dam fish trap and do outreach with visitors, explaining the operation. Please contact the Refuge at 541-493-2612 if you are interested in volunteering or have questions.