On the Fly

— For many, when the aspen trees begin turning gold and the daylight hours become less than the night hours, that means it's time to put away the kayak and the shorts and begin preparing for the long winter.

For others, it's just another excuse to go trout fishing.

Fall fly-fishing in the Yampa River can produce some great days for the anglers who have been fishing all summer and for those who are still interested in the sport.

With less insects out there to choose from in the fall, fly-fishers have an easier time choosing what to put on the end of their lines. Plus, decreased water temperatures stimulate trout, encouraging them to eat.

"Fish are driven entirely by water temperature," said Kevin Rogers, Colorado Division of Wildlife aquatic biologist.

When the water temperature cool downs in the fall, the activity of the fish picks up, he said.

"The ideal temperature for most trout is between 55 degrees and 65 degrees," Rogers said for trout in the Yampa River.

During the fall, the water tends to stay within that range.

"You also have a number of species getting ready to spawn," Rogers said.

He added that spawning can increase feeding activity.

"The fish are definitely active and they are a little less picky," said Ron Baker, an angler who works at Straightline Outdoor Sports.

One of the reasons they are less picky is because there are less insects for the fish to choose from. When colder weather sets in, much of what trout were feeding on in the summer is gone, Rogers said.

Jamie Sheridan, an expert at Steamboat Fishing Company, said the cool weather that took over the valley on Friday reduced much of the food source for trout.

"As soon as the cold weather hits, all of the terrestrials are pretty much gone," Sheridan said.

That means insects such as grasshoppers, ants, beetles and earwigs are no longer around. Plus, tricos, which are a species of the mayfly that were recently hatching at the river, are pretty much gone, he said.

In fact, most of the mixes of mayflies, cattus flies and stone flies that emerged through the summer during different times on the Yampa are gone.

Aquatic insects in the river go through a couple life stages, Sheridan explained. After the larva stage, a fly will spend much of its life as a "nymph," living in the riverbed and feeding on organic matter. It can stay in that stage from 364 days to three years. Sooner or later, when the conditions are right, the nymph will rise from the river bed, come out of the water, hatch out of the nymph body and emerge as a winged insect to look for a mate.

The male insects die after they mate. The females lay their eggs and then die, starting the process over again.

"It really depends on the weather conditions when the bugs start to hatch," Sheridan said.

While most insects wait for warmer weather to hatch, some emerge in the fall. Mainly, a mayfly called the blue-winged olive and a fly called mahogany dun is all that is on the river now, Sheridan said.

He added that fish will feed on the insects at three stages: when the nymphs become more active and start moving to the surface of water, during their most vulnerable time of emerging from the nymph body and as a winged insect.

Plus, trout often feed on "spinners," which are the dead bug falling to the ground after mating or laying eggs.

Anglers can choose from a variety of mahogany dun or blue-winged olive flies, nymphs, emerging patterns and spinners.

The fish also will be looking to feed on minnows. So putting a streamer on the end of the rod, which imitates a minnow, also works good.

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