How Long Does a Musky Live?

You have to have a pretty good life span to hit the size of freshwater “wolves” like northern pike and musky. These large popular sports fish reach some really amazing sizes and are known for being fighters who own the cold freshwater areas they thrive in.

But when you see a 40 or 50 inch musky, how old is that fish?

While it is possible for muskies to live north of 30 years, this is relatively rare. Most adult muskies live over a decade and most male musky die in two decades, with the largest females being the ones that make it 30 years or more. Muskies in very cold water tend to live a little bit longer than those in warm waters.

While a definitive scientific study on the upper most age of muskies hasn’t been done, based on the studies that have been done and data we have, we do know a lot about just how old a musky can get.

wisconsin growth rate chart
Wisconsin Growth Rate Charts for Musky

Just How Old Do Musky Get?

So let’s start with the ceiling. The world record sized muskies were a touch under 73 inches long, a touch above 70 lbs, and any fish even close to those sizes are almost certainly 30 years old.

How do we know this? Studies of musky kept in hatcheries, age indicators on the large fish, as well as well established average growth charts. At a certain size you may not be able to tell the exact age, but a fish a certain length or weight you know is within an age range.

The biggest muskie need to be over 30 years old to hit that size. Even then, many trophy sized musky are between 13 and 25 years old.

Hard Truths in Aging Muskies:

  • After 10-12 years obvious signs of aging no longer exist. Think of it like milestones growing up. Age 14 learner’s permit, age 16 driver’s license, age 18 adult, age 21 can drink then…..age 65 retirement? Musky are the same way – after 10-12 years there aren’t CLEAR defining points of age on a year to year basis anymore.
  • While many studies have been done on muskies, growth rates have proven to vary based on fish kept in captivity versus those in the wild. Some live longer in captivity, some less, so that can throw off numbers.
  • Marking and tracking fish is harder than most people believe, and having electronics that work underwater for 30 plus years…well good luck with that.
  • Despite all this as long as we understand general growth rates, average growth rates, and localized growth rates, we have the ability to give a fairly accurate age range for how old any musky from a given area is.

Understanding those points will help you more accurately understand how estimating the age of a musky works.

Methods for Determining Musky Age

There are three main methods used by biologists to determine the age of a particular musky.

Here’s a brief overview of each:

Analyzing Muskie Scales to Determine Fish Age

First, the non-lethal method, analyzing scales. Taking a look at scales under a microscope reveals a wide array of lines that can give a hint as to the actual age of the musky.

While the obvious “Like rings in a tree” analogy is far from perfect, the comparison is similar enough. For fish of up to 10-12 years of age this tends to be a very accurate way of determining a musky fish’s age.

However, recent years have shown that this method gets less and less accurate the larger and older a fish gets.

So think of this as a good beginner’s rule of thumb.

The Fin-Dorsal Ray Measurement to Determine a Musky’s Age

There is a fin/dorsal ray measurement that is used by some wildlife biologists as another method of measuring a musky’s age. This is a favorite of many biologists because there is an extremely low mortality rate so the fish usually survives and continues to age and grow.

This also gives a slightly more accurate range than the scale method once you hit musky that are 12 years old or older. While not necessarily perfect, it’s going to be closer than the scale method for teenage muskies or even those muskies who have a full two decades under their belt.

The Cleith Method

This is a last resort. The most accurate of all ways to determine the likely age of a musky, it’s also one that is almost always done on fish that are dead (usually taken from a taxidermist). This is done because this method is fatal to the fish if it’s still alive.

The Cleith Method measures the actual calcium build up from the Otiloth Bones. What does this mean? You’re scraping calcium off the musky’s skull and studying the size/depth of the calcium buildup.

This is the best method for pinpointing an exact age of any given musky, but for obvious reasons this is only done on fish that are already dead because a live muskie couldn’t survive this method of determining its age.

A great basic guide to these methods and how they work can be found here.

How Old Is a 40 Inch Musky?

While the exact age is going to vary based on climate, food supply, and local ecosystem, the general age range of a 40-inch long musky is going to be…variable based on water conditions.

Can’t emphasize that enough yet here are published numbers from certain bodies of water that can give you some guidance for the age of muskies in your area.

  • Wisconsin: 6-7 years old for a 40 inch musky
  • Minnesota: 7-9 years old for a 40 inch musky

As more reliable studies from other areas are done I will come back to add their numbers or update these if they are old.

How Old Is a 50 Inch Musky?

Again, a lot depends on water. Jerry Younk of the Minnesota DNR answered that in northern Minnesota the range could be anywhere from 13 to 21 years for a healthy musky to make it all the way to the 50 inch mark.

Check out the full original interview HERE.

  • For Wisconsin the DNR estimate is 14-15 years to reach this size.
  • For Minnesota the DNR estimate is 13 to 21 years to reach 50 inches.

In warmer waters it’s possible for a musky to get there on the lower side of that age scale. But the fish also won’t live as long. In colder waters the fish is likely to be on the high side of that scale or older.

But it will also live even longer…possibly long enough to hit that 60 inch mark.

How Old Is a 60 Inch Musky?

First of all – holy moly THAT is a giant OLD fish!!! Appropriate superlatives aside, if you catch a musky that size you are catching an old woman queen among muskies.

For Wisconsin the DNR estimated age of a 60 inch musky would be well north of 30 years old.

This is going to be true of virtually anywhere else, as well. While the explosive growth that muskies are known for give you huge fish at even 5 or 10 years old, that growth rate inevitable slows.

This means going from 50 to 60 inches takes a LOT of time and years of surviving in optimal conditions to continue to grow to that enormous size. You may also be flirting with world records for weight based on the size/style/mass of the musky.

We cover these side topics in more depth in our “How Big Do Musky Get” article, as well.

Colder Climates Vs. Warmer Climates

Climate does matter when it comes to the size of fish. Since musky can naturally be found further south than the pike, there’s also a pretty good comparison of how musky grow in warmer waters versus colder.

In cold water climates big musky are going to be older than their similarly sized cousins to the south.

In Conclusion

Musky are a fish that have an impressive life span. If you are dealing with anything close to a world record sized musky you know that fish is almost certainly over 30 years old.

While there isn’t a solid determination on what the ceiling is, chances are that musky don’t hit 40 years of age.

While it can be impossible to know this, so few fish hit 30+ years, and it takes a lot of energy to maintain biological health at that point. This is especially rare with freshwater fish like the pike and musky, which makes it all amazing when you realize just how old those giant trophy sized musky really are!

Other Resources of Interest on Muskies