Water Temperature

Water temperature is always important, no matter what you are trolling for on the Great Lakes ; yet many  fisherman never even think to consider it.

Because fish are cold blooded, they take on the temperature of their environment. That doesn’t mean they like it though. Every Great Lakes game fish has its own prefered optimum temperature zone where they are most active and where important things like eating, migration and spawning occur. The Great Lakes fisherman who knows the basics about water temperature, as it relates to salmon and trout, will have a big leg up on the the ones who ignore it altogether.

Each specie of salmon and trout has a different preferred temperature range,  as does the bait they eat for the most part. Lake Trout like the coldest water around: 40 to 42 degree range.  Chinook salmon seem to like 44 to 46 degrees,  Steelhead and Coho like 46 to 48 degrees and  Browns will hang in around  48 to 52 degrees. In March or April, just after ice out, look for the warmest water on the lake.

Prefered temperature range or zone  is the place to begin hunting for fish, but that does not mean they will always be found there. Depending on the time of year, and  the specie you are after, things can change from day to day. In the Spring, just after ice out, salmon and trout can be found at the warmest part of Lake Michigan.  The warm water discharge lines at the power plants at the southern end  of the lake in Illinois and Indiana are always the best places to start. This is where forage fish go to eat. Coho Salmon, Steelhead and Brown trout congregate there to hunt for and garbage up on the schools of those forage fish.

Big Chinook Salmon are a cold water species, so look for them in temperatures below 50 degrees. The exception is when they come into spawn. At this point in their life temperature is not important. Keep your baits in 45 to 52 degree temperature and you will increase your odds on big fish. When I am catching small fish, I know the water is too warm for a trophy. It is time to adjust the tackle to colder water. A temperature gauge is a tool a salmon fisherman cannot be without.  Clear water and sunny conditions are the enemy. This scenario will turn off most fish. However, some fish can be had when certain presentations are used. Using downriggers is a popular method to run tackle with many variations possible. In sunny conditions increase your downrigger leads to 100 feet or more. By running long leads you work water undisturbed by noise and turbulence of the boat. Leadcore is another good choice attached to a Planer board. The planer board is run well off to the side of the boat out of the travel path. Leadcore is graduated to allow four to five feet of depth for every color. Five colors will run lures approximately 20- 25 feet down.  A full core of 100 yards will bring  lures down forty to  fifty feet down. This allows you to fish any depth you want and is a killer for huge kings. Chinook live four and a half years and it makes sense that they will be the biggest at the end of their life cycle. These monsters will be the most aggressive and easiest to get in the months of July thru September. Kings over twenty pounds can be caught in April, although this is the exception to the rule.

Weather fronts, sky conditions and barometer readings are other important factors  Always look for some barometer movement. A steady barometer may offer a great chance to get some rays,  but it is not conducive to trophy fishing. There are many other factors that can affect your luck as well. When conditions seem to be fairly normal, salmon and trout can be super active during major and minor feeding periods shown daily on the Solunar tables:  http://www.greatlakestrollingflies.com/fishing-tips/solunar-tablesbest-time-to-fish/  Always check check them before leaving on a fishing trip! If you know when the major and minor periods occur, you can work harder during those times to better your chances for a big day! For those of you that think the Solunar tables don’t work, or never heard of them, do yourself a big favor and use them!

The  salmon troller that knows something about water temperature, and the variations as it relates to the specie that is fished for will have a leg up on  anyone that ignores  those conditions altogether. 

It helps to know about the phenomenon of water temperature change.  Freshwater becomes densest at 39 degrees. During winter, as portions of the big lakes freeze at 32 degrees, this 39-degree water sinks to the bottom. Then, Spring runoff and the sun’s higher rays from the approaching Summer creates a vertical wall of water called a “thermal bar” or interface. Baitfish, salmon, trout and other fish are drawn to the warmer temperatures produced by these thermal bars. Most Lake Michigan fisherman are aware of this as hot spot and and will troll along their edges , and to “stitch the seam”, that is, zig-zag back and forth across the interface. Besides monitoring surface temperature with a temperature probe, changes in water color, baitfish schools on the graph, current swirls, floatsam, herring gull activity and slicks should not be ignored.

“Slicks”– smooth water surrounded by ripples- often denote a thermal bar, which could be 0ne hundred yards to one-half mile across.  Sometimes the the difference is dramatic.  One time I found a Lake Michigan thermal bar that resembled a rip tide. There was all kinds of junk in it, like tires, lumber, bottles, cans, sticks, plastic, leaves and other stuff. The temperature difference must have been severe. I trolled the edge until I limited out.  Never pass up a slick……you will catch fish!

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