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Adopt-A-Fish Update: May 13, 2004 just part of the study Montana Fish, Wildlife and Parks This week, some of the crew had some training to do and, with the weather being as bad as it was, we didn’t do a tracking run for Missouri River Adopt-A-Fish. It’s not that tough guys like us can’t handle the rain, snow, sleet, 40-mile-per-hour wind gusts, cold temperatures or those Missouri River rollers -- waves that build with an east or west wind. It’s just that it’s tough on our equipment. So instead, let’s talk about our project. Last week, we had a little Biology 101 on what it takes for little fish to be recruited into an adult population. This week, I’ll tell you how measure that and what can be done to improve recruitment. Our project is called the Fort Peck Flow Modification Project. For this project, the Corps of Engineers is proposing to release more water from the Fort Peck spillway in May and early June. This will be like the natural flows that were seen before the Fort Peck Reservoir was established. In addition to the higher spring flows, we feel that water being released from the spillway will be warmer than the water being released from the powerhouses of the dam, which comes from the bottom of the reservoir. Also, when the water comes down the mile-long spillway and crashes into the plunge pool below the dam, it will stir up silt creating higher turbidity – muddy water that prairie river fish seem to like. Since we have been in a drought for so long, the reservoir will not be at the spillway gates for many years. So what we’re doing is gathering baseline data – information on the fish before we make a spill over the spillway. One major part of that is to research movements of many native species, especially those that are endangered or are of special concern. When the spillway runs, will we see a shift of a large number of fish that use the Yellowstone River to more fish using the Missouri River? We won’t know unless we find out how many are using each river now. Another part of the study is larval fish sampling – taking a look at the little fish that hatch each year. Sure, we may see more fish coming up the Missouri when the spillway runs, but are they spawning? With this portion of the study we will be able to compare numbers of larval fish we are seeing now to what we expect to be larger numbers during the spill. We also expect to see an earlier spawning date than we do now due to the warmer water temperatures. One theory of the pallid sturgeon’s lack of recruitment is that when their eggs hatch, there may not be a long enough stretch of river for the larvae to drift before they end up in the headwaters of Lake Sakakawea and end up smothered by silt at the bottom of the reservoir. We are also looking at how much river is needed with our larval drift component. From this, we will better understand how long a stretch of river is needed before the larvae can select a habitat to hold in and are no longer at the mercy of the current. For example, it may be determined that the fish need to spawn above Wolf Point or maybe Frazer, in order for the larvae to survive. If they spawn lower on the river than that, there isn’t enough river before they drop into Lake Sakakawea. Lastly, in the fall, we look for young of the year sturgeon. At this stage of development, the little sturgeon are a couple of inches long, so we can much more easily determine the difference between shovelnose and pallid sturgeon. We will hopefully see larger young of the year fish after the spillway release, which will have a better chance recruiting into the population. Will the spillway release help our native species? Only time will tell. |
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