According to Christy Graham, trout management biologist with AGFC, the experimental strains of rainbow trout the commission has introduced below Beaver dam in the past two years have shown growth rates of six inches in eight months, while the typical catchable size of rainbow is only growing two inches in the same period of time. However, the annual rate of survival of the experimental strains is only six to twelve percent.

Graham spoke at the Arkansas Chapter of TU Monday night. She also said the electrofishing catch rate of trout per hour is down over the last three years. The commission is stocking 5,000 browns per year now instead of skip stocking every other year. It has also begun to look at the forage base and is doing an annual sculpin sampling and hopes to include macroinvertebrates in the future.

© 2012, Scott Branyan

A float on Table Rock Lake last week reminded me of some late season mayfly activity anglers may see in the Ozarks, and this includes the White River tailwaters. The main species one might encounter in early to mid-September are Hexagenia or “Giant Mayflies” and Stenacron or “Light Cahills.” I found a rather heavy hatch of Hexs around Eagle Rock, MO early last week. That same night, I had a beautiful specimen of a male dun Cahill light on my camping gear at Viney Creek Park.

This male Cahill dun shows an amazing display of color.

Anglers can be rewarded with fishing a “surprise” late hatch by keeping some Light Cahill parachutes and pheasant tail nymphs in their boxes through the summer and into early fall. Sizes 14-16 should cover the Cahills.

Still drying its wings and tails, this late season Giant Mayfly dun rests on a rock above the water line.

For Hexs, you need something a lot larger, and do not overlook the nymphs since they are quite large and burrow into silted bottoms on both lakes and rivers. Larger soft hackled wet flies are are good for their imitation. Choose grays and browns for color.

I’ve yet to see an Ephoron or ”White Mayfly” emergence this September, but one should be expected in the area starting around the middle of the month on warmer afternoons. Light Cahill and pheasant tail nymph patterns work for these too in about a size 14-16.

These are the goodbye emergences of mayflies for the year on the White River tailwaters except for some Tiny Blue Winged Olives which may appear later this fall and winter.

© 2012, Scott Branyan

I’ll be presenting a program on White River Hatches at the Arkansas Chapter of TU in Fayetteville on March 5th.

This presentation will discuss some of the major hatches we see on our tailwaters and how you can use knowledge of hatches to better your effectiveness and enjoyment of fly-fishing.

Looking forward to seeing many of you then.

© 2012, Scott Branyan

Arkansas Game and Fish Commission biologists continue to evaluate some different strains of rainbows to complement their current stocking strategy. Recently, some McConaughy rainbow fingerlings were stocked in both the Little Red and the White Rivers. According to trout biologist Jeff Williams, “The fingerlings averaged about 3.5 inches in length and were marked with an adipose fin clip.”

The McConaughy rainbows (pronounced mih-KAH-nuh-hay) originate from the North Plate River Valley above Lake McConaughy in western Nebraska. There the rainbows make a natural spawning run out of the lake into the groundwater tributary streams in the winter and reproduce. The smolts then migrate into the lake for a period of 2-3 years before returning to the streams to spawn as 3-4 pound rainbows.

Williams says the trout biologists here have been investigating using other strains of rainbows in the White River tailwaters since data suggests the typical stocked rainbow is not getting the growth rate desired in the catch and release areas which have recently been studied. Williams thinks a “wilder” strain such as the McConaughy bows might be better foragers in the tailwaters. In 2008, AGFC stocked a small number of McConaughy’s in the Little Red. The high water that year foiled attempts to sample and evaluate those efforts.  A few were recaptured and those had seemed to grow extremely well.

This summer AGFC stocked about 12,500 fingerlings in the Bull Shoals Catch & Release area and an equal amount at Rim Shoals. These were stocked the end of July.  About 25,000 fingerlings were stocked in the Little Red about the same time as well. 

An initial sample was conducted last week and monthly samples in the coming year will be taken to monitor growth and survival.  The first sample at Bull Shoals dam found a pretty good number of the fingerlings, which were concentrated around the cedar trees that the AGFC habitat program had put in last year.  At Rim Shoals far fewer fingerlings were found. 

AGFC has received a verbal agreement from the Norfork National Fish hatchery to raise some McConaughy’s for the Norfork Tailwater, and Williams anticipates those to be ready within the year. 

© 2010, Scott Branyan

Corrective measures are needed early again this year and probably point to another bad low DO season. Vents on turbines at Bull Shoals and Norfork dams were opened on July 14th this summer as dissolved oxygen readings fell below the state standard of 6.0 parts per million for trout waters. This is an annual occurrence, although it is typically a more severe problem during high water years. This is the third back-to-back high water year for the White River reservoirs, which is historically rare. The Corps started taking corrective action about the same time the previous two summers.

As the lakes stratify in the summer months, decaying matter in the water on the bottom of the lake uses up oxygen through microbial action. As it becomes depleted of O2, and as the powerhouse runs heavy to meet hydropower demands, that dead water gets pulled through the turbines and into the tailwaters endangering trout and other fish and aquatic life. This has resulted in numerous fish kills over the years. And it is particularly troublesome as the low DO condition worsens into the late fall of the year just as brown trout are attempting to migrate to gravel beds to spawn below the dams.

Even though a dissolved oxygen committee was formed by Governor Bill Clinton in the early 1990s to correct the problem, a decision on a remedy has been elusive and no money has come forward to fix it. The state argues this is a continued mitigation problem endemic to the building of the dams, and the Corps of Engineers counters the dams were authorized by Congress for flood control and hydropower, and the fishery is mitigated through the federally funded hatchery system which is run by the U.S. Fish and Wildlife Service. The Corps says it can’t be held responsible for the fact that low DO, which falls below the state water quality standards for trout of 6.0 ppm, limits successful spawning of trout in the river system and occasionally results in fish kills. The low DO is a problem with watershed quality, it argues. 

If the trout tailwaters were only a put-and-take fishery, then occasion fish kills might be acceptable. But impacting as it does just at the time of the brown trout spawn makes this a worse case scenario. The smallmouth fishery that was here before the construction of the dams was a natural, not a put-and-take fishery. Further, the tailwater trout fisheries have proven they can successfully compete with well established wild trout fisheries as far as producing several trout species which grow to rival trout in their native ranges and even produce world record fish. That successful natural reproduction of brown trout in the tailwater system is not only possible but likely is now without question.

The biology textbook I have states a DO level of 8.0 ppm is necessary for healthy naturally reproducing trout and in order to have a successful spawn. A DO level of 6.0 falls short of this, although Game and Fish biologists say it is a realistic number to strive for given the annual problem with the anoxic water from the dams. The Corps would like to see the state drop the water quality standard for trout to 5.0 ppm as corrective measures are expensive.

According to readings from USGS gages today, DO below Norfork dam today dropped to 4.3 milligrams per liter (this is the same as parts per million or ppm) under full generation. When this happens, the Corps usually implements a maximum load restriction which helps keep the DO level higher. As the problem worsens maximum load restrictions are further reduced, since heavy generation pulls more anoxic water off the bottom of the lake and the vents on the turbines which siphon air into the system become less effective at higher generation loads. The Corps has yet to implement those restrictions this summer. But I would look for it to happen soon.

Arkansas Game and Fish Commission biologists started using stocking restrictions on Norfork and Bull Shoals tailwaters a few years ago when DO readings consistently stay low. As the reading worsens look for these measures to be put into effect this fall. It looks to be another bad DO season on the tailwaters. The DO problem goes away as soon as the lakes finish turning over usually by December 15th.

© 2010, Scott Branyan

Arkansas Chapter of Trout Unlimited held its first meeting of the fall at the Whole Hog Cafe in Fayetteville last night. Jeff Williams, trout biologist with AGFC, spoke. Williams opened his presentation with a summary of the proposed trout regulation changes which are being considered by the commission this month. They involve:

• Removal of the Sylamore catch and release area on lower Bull Shoals tailwater
• Change in tackle regulations for Bull Shoals and Norfork tailwater catch and release areas
• Extension of Norfork tailwater catch and release area

The removal of the Sylamore catch and release area has been recommended because of temperature considerations making it marginal trout water during the summer months in about 7 out of 10 years. On the change of tackle restrictions on Bull Shoals and Norfork catch and release areas, Williams originally recommended allowing multiple treble hooked lures and removing the barbless requirements. However, he noted there had been enough comments come in with objections to barbed tackle that the latest recommendation is to allow “multiple hooking points but all barbless.” This is still in line with the best scientific studies and is a least restrictive regulation allowing more types of anglers to fish those special regulation areas, he said. This will also do away with the single hook rule which has prohibited droppers in catch and release areas.

The reason for the recommendation to expand the Norfork tailwater catch and release area is based in the results of two studies done by the University of Arkansas Fish and Wildlife Cooperative Unit. According to Williams, one of those studies found the survival rate of rainbows was not as high in the present Norfork tailwater catch and release area. It suggested rainbows tend to stay in the catch and release area; however, higher angling pressure there results in a significant lowering of the survival rate. The length determination of the recommended 2.6 mile catch and release zone was limited by social considerations of current dock businesses on the tailwater. This summer, dock owners on the lower tailwater section have organized opposition to the proposed zone and involved at least one commissioner in recommending a reduction of the proposed catch and release area on the lower end. The commission will vote September 24th on the fisheries staff recommended proposal and one introduced by Commissioner Ron Pierce, which reduces the size of the catch and release zone to two miles. During questions and answers, several chapter members were critical of the proposal introduced by Pierce and commented it was outside the spirit of the new trout management plan process and that the commissioner violated the state’s sunshine law by meeting privately with other commissioners and parties to discuss alternative proposals.

Williams spent the last half of the program summarizing a new Beaver Tailwater Growth and Mortality Study. The new study was initiated in July of this year. Eight thousand wired tagged rainbows were stocked in the tailwater in July. The trout have a 2mm wire coded tag in their snout. Monthly sampling will document growth and survival rates of these fish. Williams noted that a change in their abundance will give biologists data to arrive at mortality figures, and a change in length will help them determine size and growth.

Brown trout in Beaver tailwater are showing good growth rates of 5½ to 7 inches per year, while rainbows appear not to be growing. In previous sampling, biologists noted trout are full of algae and that rainbows are not normally herbivores. This seems to discount the working theory that the lack of growth is from too high a density of fish in the tailwater. Williams noted it may be a problem with the strain of rainbows used (Arlee). Experimental stocking of McConaughy rainbow fingerlings (a wild strain of rainbows originating from the North Platte River above Lake McConaughy in Nebraska) in the Little Red River in 2008 has shown good results, and AGFC is pursuing stocking more McConaughy rainbows in the future.

Williams noted that outdated information on the trout management plan on the AGFC website has been removed, and new data and descriptions of the individual tailwater plans are in the process of being added to a redesigned web page for the trout program.

© 2009, Scott Branyan

I had a client ask me the other day about whether fish have cognitive learning ability. Fish do exhibit sensitive foraging, where their foraging location, exposure to risk and time spent there vary accordingly. But much of this is instinctive.

However, I ran across an interesting article today. It cites a study that suggests fish do learn to find new and better food supplies much the way humans do despite their relatively small brains.

© 2009, Scott Branyan

Since I discovered large deposits of scuds in dewatered areas along the White River after the Buffalo River flooding in March (see the photo in the 2008 photo gallery), I started trying to find research on the effects of flooding on aquatic insect crops. After doing some casual reading, here are some of the things I discovered.

1. Much of the disturbance of insects has to do with how much gravel is displaced and rearranged.
2. Some research has shown that a single flash flood of a small arid stream can remove as much as 98% of the standing crop of macro-invertebrates.
3. Aquatic insects, however, are very resilient and are able to recover to significant population levels starting within one generation.
4. After a major flood event, midges do particularly well at first because of their short life cycles.
5. Frequent flooding in streams tends to promote less diversity and density of insects.
6. Major displacements may have the benefit of introducing and promoting more diversity among species of aquatic insects.

So the news is generally good for aquatic insects in the White River system, although I did not find anything that specifically addressed scuds and crustaceans and flooding. This is consistent with the increase in more caddis and mayfly species I ‘ve noticed after the floods in recent years.

Would be interested in any thoughts from biologists or researchers on the topic. Sign up and leave a comment.

© 2008, Scott Branyan