Thursday, 13 October 2011 09:48
"Red sky at morning, sailor take warning," was not exactly the sunrise prediction the crew wanted to hear as they loaded gear for a three-day overnight float down the White River. Fortunately the weather forecaster was wrong and the three-species crew enjoyed a beautiful, if long, day as they searched for native young-of-the-year fish.
Division biologists Jake Johnson, Sam Hadden and Trina Hedrick quickly sort through the seine haul looking for native fishes.
Photo by Ron Stewart
Every fall, biologists from the Utah Division of Wildlife Resources search the slower waters of the Green River and some of its tributaries like the White River for young-of-the-year fish. This effort is part of a larger program to monitor and enhance the health of the populations of seven rare (sensitive) native species.
Four species are federally protected under the Endangered Species Act and three other species are protected under Conservation Agreements between Federal, Tribal and State wildlife agencies. These Conservation Agreements are designed as a proactive measure to help keep targeted species off the Threatened and Endangered Species List.
Endangered fish in the Green River drainage include the Colorado pikeminnow, bonytail, humpback chub and razorback sucker. The three species under Conservation Agreements are the bluehead sucker, roundtail chub and flannelmouth sucker. The White River crew was specifically looking for the three species under the Conservation Agreements.
Using a fine meshed seine net, the biologists sampled slow water areas, called slackwaters, in the main channel and in backwaters, areas of water connected to the river that do not flow all the way through. In the Green and Colorado rivers biologists focus on seining backwaters, but on the White River there is a limited number so other potential nursery areas are also sampled.
Backwaters are extremely important habitat for young-of-the-year fish as they have almost no current and are generally warmer than the main channel. Stronger currents can wash smaller fish downstream and backwaters get warmed easier by the sun as they are generally shallow and have little exchange of water with the main channel. These slow, warm waters become excellent nurseries for many young-of-the-year and other small fish including the seven on the State and Federal lists.
The first few net pulls of the day were a little discouraging, few fish were netted. These pulls were in the slackwaters of the main channel where the fish can escape around or under the nets easier. The next pull was a bonanza.
This net pull was through a backwater and when the crew looked at their catch, there were hundreds of little fish. The biologists started sorting as quickly as they could to pick out native fish.
"Just toss anything that looks a bit different into the bucket, we can sort them out later," was the advice given to the less experienced crew members. Easier said than done as most of these fish were under two inches. At that size, it takes an experienced biologist to point out slight differences between species in order to accurately identify them. Soon however, all members of the crew were sorting and identifying native fish.
The history of the fish being studied is one of survival.
These ancient survivors lived through the discovery of the west, through ice ages and the time of mammoths and giant sloths, through the ages of dinosaurs and giant reptiles and back through the creation of the Rocky Mountains.
They lived in a river system that at one time flowed from the Utah-Wyoming area to the northeast and into the Mississippi drainage. As the Rocky Mountains, including the Uinta Mountain range, were uplifted ( shoved up), the river was blocked, forming a large inland lake. As more water flowed in, it broke through and connected to river systems flowing south to the Gulf of California. The river, through geologic time, carved through mountains and plateaus creating steep canyon walls.
This river drained a huge geographical area and so the fish were subjected to massive cold, muddy spring floods. By late summer, the flows were minor and the water warm and mostly clear. During winter, the surface of the water froze and the fish had to survive for months under the ice. Then throw in the Ice Ages, times of drought and blistering hot years.
To live through the changes in the environment and the river, the fish had to adapt.
To survive the massive flooding they developed streamlined bodyshapes with flattened noses and humps on their backs. These odd shapes act as hydrofoils to keep the fish steady in the fast, strong currents. Their large powerful tails evolved to help them swim through the currents of whitewater rapids and allowed them to swim long distances during migrations to reach areas suitable to spawn where their young could then drift to nursery areas. Other adaptations included being able to survive radical changes in water temperature.
Some of the adaptations were more behavioral changes, such as seeking out the best places to summer or winter and spawning during the end of the spring floods so their young will be carried into the surrounding flooded lands. These flooded wetland areas provide a sanctuary in terms of escape cover, high quantities of available food and warmer water that helps them to grow faster. As these wetlands dry, the young fish make their way back to the river.
Only the true survivors, those able to evolve unique adaptations to meet the changing conditions of the river and time managed to make it through to face their biggest challenge, man.
Most of the fish the biologists seined from the White River were red or sand shiners, introduced fish originally from the Mississippi River drainage. Crews working the Green River also found mostly non-native fish. Due to decades of legal and illegal introductions, over 60 non-native fish now reside in the Green River drainage. These species are now competition and/or predators on the beleaguered populations of native fish.
Non-native fish, exotic diseases, and habitat changes caused by dams, water diversions and streamside developments have all taken their toll on the native fish of the Green River drainage.
However, it is because these fish are survivors that gives the biologists hope the native fish of the Green River and its tributaries will be able to survive the human-caused problems as well as they did those created by the changes in the seasons and the earth's geology.
As the fish in the bucket slowly increased in numbers, you could see smiles beginning to appear on the faces of the biologists.
They didn't find any of the four endangered fish, what they did find were good numbers of the three species they were looking for, flannelmouth suckers, roundtail chub and bluehead suckers. They also found and recorded another native fish, the speckled dace.
Over the next three days, as the crew pulled nets in the backwaters and slow moving currents of the White River, they saw few other visitors. The only voices were their own echoes. They shared the canyon and the river with shorebirds, waterfowl and other wildlife.
As they pulled the seines, the number of native fishes recorded grew. The percent of native species they found was higher than other crews were finding in the Green River and most other upper Colorado River basin areas.
For the third consecutive year, the numbers of these rare fish discovered were clear indications the White River is an important spawning area and nursery habitat for the three species.
The biologists believe it is the wild nature of the White River that makes it such a critical stronghold for the native fish. Relatively natural flows and its rugged surroundings make the White River extremely unique and highly important to the survival of the native fish that evolved there.
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