First we'll start with the basics. For salmonids to survive a return home, water temperatures need to remain below 68 degrees fahrenheit . This number, from my brief research, will allow upstream migration of anadromous salmonids ( Chinook, Steelhead) that are genetically prepared to survive warmer flows. Some salmonids ( like sockeye) are not as robust and will not do as well in these conditions. It is very important to note that the survival of all of this fish at this temperature is dependent on the lack of outside stresses. Meaning simply, not fighting for their lives on a end of a line or being chased by a predator. To recap, fish can survive 68 degree water, but only if we leave them alone. Water temps over 70 can be lethal and over 80 terminal. The die-off we’re seeing in the Willamette is a sample of temps in the terminal range.
As I said earlier, conditions do change and as summer gives way to fall our days shorten up, while our nights grow longer. Longer nights allow for more overnight cooling providing much better fishing conditions in the early hours of day. For summer Steelhead that “happy place” is between 50 and 60 degrees. Many of the anglers I contacted about this article pull the plug on any interaction with Steelhead at 65 and even then take great care to land and release in a timely manner with no removal of the fish from the water at all.
Trout have a similar set of numbers dialed into their thermostat that make them happy and willing to participant in our angling efforts. 50-63 degrees seems to be the sweet spot as observed by my good friend and Trout guru, Brian Silvey. While temps below 40 and above 70 are not conducive to successful Trout fishing, fishing in those warmer temps put fish in danger of not surviving an encounter. If the water’s warm, do no harm.
Now, all of this doom and gloom does not mean you have to hang up your fishing kit and go swing golf sticks. Not at all. What it does mean is that we all need to be aware of the conditions and adapt. Here are 10 tips to get you through the summer heat.
1. Carry a thermometer and use it. Knowing the water temp will add to your success and save fish.
2. Fish early in the day when the water is cooler and take the afternoon off if temps break into the danger zone over 65 degrees.
3. Fish higher up in the watershed. Rivers and streams warm up as they flow to the sea. Well forested rivers stay cooler than waters flowing through an open landscape. Explore new water.
4.Tailwater fisheries provide cooler water conditions as you move closer to the dams that create them.
5. Try lake fishing. Many of our Cascade lakes stay much cooler in the summer months as they are spring fed.
6. Explore the coastal waters off beaches and jetties, or visit Puget Sound.
7. Utilize the USGS website to track flows and temps.
8. Maybe succumb to the carp and bass craze.
9. Have fun and learn something new this summer.
10. Share this information with others