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Our new President, Nick, submitted this following our last monthly meeting: Cache Anglers held their monthly meeting tonight at RoundRocks Fly Fishing in Logan. Dr. Mark Vinson presented information on the aquatic invertebrate population of the Green River below Flaming Gorge Dam and what the fish are eating. Mark also gave us an update on the Logan River Salmonfly Relocation Project. Let's start with the Sammies...At the nymph release site, sampling has shown no nymphs present. This is a heavy water site, and it is possible the released nymphs were washed further downstream than the survey area. Last year, this site had pteronarcys exuvia present, indicating that some transplanted nymphs did hatch. At the adult release site, sampling has shown nymphs present in the 1yr old age class. Looks like some of the adults got busy & did what they were supposed to. For the Green River project, Dr. Vinson & his crew surveys several sites for aquatic invertebrates, from the dam down to the state line. For fish stomach content surveys, Vinson worked alongside DWR biologists as they electrofished locations in the A section, working the shockers by boat. Vinson collected stomach samples from 50 fish at the tailrace boat ramp (main put-in) and 50 fish at Little Hole. This is consistent with the annual data collection method dating back to 1995. The biomass numbers for the Green (averaged from all survey sites) shows an average aquatic invertebrate density of 12,000/square meter. To put that into perspective, the Logan River has a density around 2,000/square meter. There are about 20 species present in the system. Of those, four species make up 93% of the overall biomass. The most prevalent is hyalella azteca (little grey scud) taking up 66% of the count. The rest of the top group include chironomidae, ephemeroptera and simuliidae. The Green River fish are definitely meat eaters. 20% of the browns sampled had fish remnants in their stomachs, while 12% of the rainbows ate their cousins. Mice remnants have been found in quantities that reflect cyclical rodent populations, with some years showing as high as a 10% stomach presence, and other years (like this year) having 0% presence. New Zealand Mud Snails have increased rapidly in the system, including appearance in the stomach samples. They were first found in survey fish in 2001 with a very small presence. In 2005, 60% of the fish had NZMS in their stomachs. Vinson said ingestion is likely incidental, picked up while going after other invertebrates. One of every 20 fish over the life of the study is found with fishing flies in their mouth. You guys need to tie better knots & give up the 6x. |
Cache Anglers is an organization dedicated to enjoying and preserving the waters and fish in and around Cache Valley Utah. We are a chapter of Utah Trout Unlimited. We are fortunate that Cache Valley has a wide range of opportunities to enjoy fishing. There are three main rivers that empty into the valley, and numerous streams, lakes, and reservoirs. In addition, Cache Valley is central to some of the greatest fishing in the west. An hour travel can take an angler to the Provo River to the south and the South Fork of the Snake River to the north. A little more time and a person can be wetting a line on the famous Green or Henry's Fork Rivers.