By Ethan Hollifield
There’s been this idea thrown around in the angling culture of North Carolina that summer is what many consider the best time of year to fish for trout. That’s correct, to an extent. There’s definitely more aquatic insect activity and nothing beats having a wild trout come up to nose a dry fly. However, water temperatures can also fluctuate to dangerously high levels that can cause trout to become stressed to the point where even catch and release fishing can ensure a fish’s demise even after only seconds out of the water. This normally starts to occur whenever the water temperature reaches above the 60-62 degree mark. It’s our responsibility as anglers to ensure that our wild trout populations are not threatened by our own mishandling or ignorant fishing practices.
The reason why water temperature is so important to trout survival is that it is the main factor in how much dissolved oxygen can be found in a given stream. Trout require a relatively high concentration of dissolved oxygen (6-7 mg/L depending on species) in order to survive. To put that in perspective, some species of carp and other rough fish can survive on as little as 1mg/L of dissolved oxygen. Dissolved oxygen concentrations are also influenced by other factors including water temperature, light penetration, water depth, turbidity, rates of photosynthesis, stream gradient, and the amount of oxygen used by respiration/ the decay of organic matter. In short, temperature plays the biggest factor in how much dissolved oxygen a stream can generally hold.
In addition to increased elevation, the overall biggest reason for cooler water temperatures in the summer is simply shade cover, provided by trees and other vegetation. The highest productive trout streams, that always have stable populations of wild fish, all have that one limiting factor shared with one another. The lowest productive trout streams suffer from a variety of issues, but increased water temperature, due to excessive sun exposure, always limits the ability for trout to survive throughout the summer when issues such as excessive development, over-mowed banks, and deforestation are presented.
So how do we approach all of this as anglers? As stated, even practicing catch and release can still stress a trout to the point where it won’t recover from being caught due to a lack of dissolved oxygen. The biggest piece of advice I can give to anglers is to carry a thermometer with them to measure the stream temperature. If it reads above 62 degrees, then the responsible thing is to leave the fish alone and give the trout a chance to survive until water temperatures cool down. Going out early in the morning when water temperatures are still cooler is also better on trout, and is normally the most productive time to fish in the summer months anyways. Trout should be fought quickly and be left in the water while the hook is removed in order to limit the amount of stress presented on the fish.
Our wild trout populations in North Carolina are only as productive as the environment allows them to be in addition to how we, as anglers, respect the resource. Fishing for trout when it is too hot is not only unethical, but also serves as a detriment to the future of our angling opportunities as well. However, if we, as anglers, do our part to help advocate and take care of our trout streams, then those resources can be available for our children to enjoy.
Ethan Hollifield is an Environmental/Physical Science Teacher and is also a guide for Southern Appalachian Anglers.