Here’s another reason why length-to-weight relationships is more important than most anglers think: You catch a walleye that measures exactly twenty inches on the board, but when you weigh it, the scale reads two pounds instead of the expected three. Your board says the walleye is precisely 20 inches long. Yet when you get him on the scale he weigh two pounds, not three.
This is where a little knowledge goes a long way, providing a measure to help determine if your catch is average, healthy or exceptional. It will also show you what that fish has been feeding on throughout the year. Understanding length-to-weight relationships can tell you alot about the health of the fishery… and it’s not always about who catches bigger fish.
Why Length and Weight Matter for Walleye
This is based off traditional weight formulas which tell you the approximate weight of an average conditioned walleye by its length. It’s not set in stone. Instead think of it as base level. A 20 inch walleye above the weight listed will have added girth. Usually, this is due to good water quality and lots of forage. A fish below that line may simply be stressed out or existing in a habitat where available food supply does not support them.
The chart illustrates all of this very well and does not gets lost in complicated mathematical equations. What you’ll notice with the scale is how much seasonality matters. Walleyes are coldwater fish and they are steady with their metabolisms during the course of the year. Females immediately post-spawn is visibly light from having recently shed their eggs. The fish drop out of the healthy range on the RI and occasionally below into poor condition range.
But then as we head towards the summer months, and water temps increase, fish begins to feed hard. Depending on where you live, they pack on the pounds from shad, yellow perch or alewives. As fall nears, these fish are now peaking in weight and packing on winter fat stores. Because of this, the exact same fish will almost always weigh more when caught in November than when it was caught in April.
The other part of this equation is regional. If you’ve fished both Great Lakes and midwest for walleyes, you’ll find your Great Lakes walleye is generally bigger then their midwestern counterparts of equal length; due to what’s available to eat. Walleyes will also get thicker than those in some other systems where there is an abundance of baitfish, making them look impressive on the scale. Yet, they may not appear as thick compared to their size potential in a higher productivity system like a prairie lake. Knowing this helps you know what to expect when you go to new water. You won’t be able to compare apples to oranges … you’ll know you’re comparing two different ecological profiles.
The biggest problem with measuring is getting the measurement right. Every calculation hinges on good measurements and most anglers fail to do this. Total length matter as does pinning that tail shut. The chart makes clear that getting the girth measured at the widest part give us our best guess.
And it points out the reason for slot limits. Protecting fish between twenty and twenty-six inches is about more than just following rules. That is healthiest segment of the population and it is the most prolific. Leave those nice females in the water and we’ll have great spawns in the future.
All this boils down to, once you know what a walleye weighs and how long it is, you no longer sit on the sidelines, you become a student of walleyes. You begin to see things other people don’t see. You realize what times of year is good for the best conditioned fish. You recognize what regions grow them out better than others. Now you understand why that 20-inch fish was just “average” instead of looking at it as just another fish. Instead of guessing, you now understand that each weigh-in becomes one more little piece of information that contributes to the bigger picture of the body of water you’re fishing. You should of seen how much it matters.