Catch-and-release musky fishing is the norm today. Most anglers care deeply about the fish they chase, and seeing a musky swim away feels like success. But here’s the hard truth: not every released musky survives, and that’s life.
Musky release mortality doesn’t usually happen at the boat. In many cases, the fish dies hours or even days later due to stress, injury, or oxygen loss. The good news? Most of the factors that cause post-release mortality are entirely avoidable. Let’s break down what actually harms muskies after release, which mistakes matter most, and how small changes in handling can dramatically improve survival.
What is Musky Release Mortality?
Musky release mortality refers to the percentage of fish that die after being caught and released. Mortality can be either immediate or delayed. Immediate, meaning the fish dies during the release as it cannot regain its strength, or delayed, meaning the fish swims away but eventually succumbs to the rigors of being caught, either through stress or injury.
Delayed mortality is the bigger issue for muskellunge. Because muskies are large, powerful predators with high oxygen demands, they’re more sensitive to specific stressors than smaller fish. Understanding why muskies die after release is the first step to preventing it.
The 5 Biggest Causes of Musky Release Mortality
1. Warm Water Temperatures
Water temperature plays a significant role in a muskie's survival after release. As water warms, the dissolved oxygen levels drop, musky metabolism increases, and recovery time after the catch skyrockets. Many experts would agree that this is one of the most significant issues for post-release mortality. While that might be the case in the coldest water systems, muskies in shallower, smaller lakes or muskies native to more Southern states are far less likely to fall victim to this issue.
Muskies acclimate to their waterway as people do to their local weather patterns. To put it simply, folks from the Northern states tend to wear shorts when the weather is in the low 50s, while folks down South are donning coats. The same goes for the animal kingdom. Fish acclimate to their water and relative temperatures, altering their spawning behavior and natural predation. Therefore, if a musky is born and acclimated to a shallow, warmer environment, the effect will be less severe. However, the same applies to a cold river musky, highly accustomed to frigid, moving water and less adapted to extreme, sudden heat; the release for those muskies is far more critical.
The takeaway here is that, at higher temperatures, both in air and in water, releases need to happen twice as fast. Faster release times reduce stress and the risk of delayed mortality.
2. Air Exposure (Seconds Matter More Than You Think)
Musky gills are designed for water, not air. When a fish is held out of the water, gill filaments collapse, oxygen exchange drops immediately, and blood oxygen levels plummet. We often underestimate how fast that damage can add up. Multiple lifts should be out of the question.
To prevent delayed mortality in this situation, it’s best to lift the musky in a calm environment only after the camera is ready. Keeping the “out of the water” time under 10 seconds will ensure a lively revival and a healthy release.
3. Improper Nets and Poor Boat Control
Unprepared anglers are often a significant factor in muskie mortality.Small nets and knotted mesh cause a host of issues for a mishandled musky. External damage, such as unnaturally bent fish, slim coat damage, and thrash marks, often occurs when anglers are unprepared with improper gear.
Netted muskies need the best chance of survival, and we can help them by providing oversized, waxed or rubberized knotless nets and a heavy helping of boat control to simplify release.Muskies need to settle before being handled.Remember, this is a wild animal.They are not accustomed to handling anyway, so their comfort and control are the only things keeping them alive. It’s important to ensure the gear used in the catch is approved.
4. Hook Removal Delays & Inadequate Tools
The longer it takes to remove hooks, the higher the stress level.
Every musky angler should have:
- Long-nose pliers
- Heavy-duty hook cutters
- Jaw spreaders (used carefully)
Cutting hooks is not a failure — it’s often the fastest, safest option. If you practice safe handling techniques, let this one be at the forefront of your mind. Buy extra hooks; the fishery will thank you. Deep hook removal attempts cause far more damage than leaving cut hook pieces behind. Preparation before the strike makes all the difference.
5. Long Fight Times (Less Important Than You Think)
This one surprises many anglers. A slightly longer fight in cool water usually causes less harm than air exposure, warm-water handling, or boatside support. Fight time becomes a major issue only when water temperatures soar, and oxygen recovery is limited. In those conditions, heavier gear that shortens battles can help. But don’t obsess over seconds on the fight — focus on clean-handling afterward.
Final Takeaway: Small Changes Save Big Fish
Bad intentions don’t cause most musky release mortality. It comes from heat, timing, and lack of preparation. Fix those, and survival rates improve dramatically. If catch and release fishing is your goal, then the causation of mortality should be at the forefront of your mind. The more you respect the fishery and the fish, the more survival rates continue to go up, and you leave the water better than you found it.