Why Are the Trout Not Rising (all that much) to Trico's in Eleven Mile Canyon (fly Fishing Report)

The fish are just not rising in Eleven Mile Canyon; at least not as they have in past years. Of course some of us are finding rising fish in certain runs on certain days and the dry fly fishing can be spectacular, but overall there is no comparison to what we have experienced in years past where it seemed like every fish in the entire river was up top sipping in bugs with their dorsal fins sticking out of the water. .  

By simply paying attention to the trico hatch over the decades my best guess involves perhaps several factors that involve energy efficiency.  There seems to be some innate “formula” that a trout uses to determine if it is energy efficient to rise to the tricos. A certain amount of energy is wasted as a trout moves to rise and suck in the bugs from the surface. Higher flows, as we have seen recently, can cause a fish to waste more energy than it is worth, and so, with an abundance of food being swept below the surface in the form of larvae, nymphs and annelids it makes “energy” sense to stay low and feed.

Visibility of the small tricos in the higher more turbulent water may also be a factor. It is just difficult for the fish to see the bugs when the current is up higher. If the trout are having a hard time finding the bugs (and keep in mind they need to eat  lots of them) once again it is just not worth it in terms of energy expenditure.

The fact that Eleven Mile Reservoir seems to be “turning over” which involves an algae bloom causing the river to be slightly off color also compounds the visibility issue. Since we are dealing with such small micro calorie bugs it seems that it does not take much to up-set the energy balance of the trout. In other words it does not take much to make it not worth the effort to feed on top trying to find tiny bugs.

Risk is also a factor. Why risk going up top to chase micro calorie tricos when the fish can lay low and feed more safely? This issue of risk may also be connected to the large number of fishermen pounding the water every morning. Are the fish simply avoiding danger? Ten to 15years ago, a short article appeared in the Denver Post titled, “The Pelican Brief”, which suggested that the fish no longer rise much in South Park because of the pelican population. Could the trout be learning to avoid fly fishermen swinging their hooks on the surface?

I think all of these variables are coming into play at once. I remember last year even with the super high  flows I had some of the best trico dry fly action at the “island hole” just below the first of the “double tunnels”. Fish were on the rise all over that run. But this year, even with a lesser flow, the fish are not rising there. So that makes me think the slightly off color is a significant variable.

I am hopeful that when the water clears up and drops we will see more fish on the rise. 

But keep in mind that as we see more fish on the rise we will also see even more fly fishers and that increase may become the more significant variable.  The issue of the fish rising or not rising makes me aware of the delicate balance within the ecosystems we fish. Small changes can have significant impacts. We should try to remember this basic ecological principle every time we step into the river and try to remember how we may play a big part impacting any ecosystem we fish.