Fish need oxygen just like you do, and more than a minute or two out of the water begins to stress most species.
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One question that comes up a lot at USAngler is “How long can a fish live out of the water?”
When you catch a nice fish you plan to release, how long do you have to remove your hook, snap a few pics, and return it to the water without harm?
The short answer is typically only a few minutes, but there are rare species like the lungfish that can adapt to dry periods by evolving to survive long periods out of life-giving water.
Anglers might find these biological curiosities interesting in the abstract. Still, most of you probably care a lot more about how long common game species like largemouth and brook trout can survive in the open air, or how long reds or specks can do the same.
Let’s get into the details and get some real-world answers!
How Fish Breathe: Gills vs. Lungs
Terrestrial animals breathe by drawing air into their lungs, where tiny structures called alveoli absorb oxygen and release carbon dioxide. This process of gas exchange provides your body with what it needs – life-giving oxygen – while getting rid of what you don’t – potentially lethal carbon dioxide.
Every breath you take replenishes the oxygen carried by hemoglobin in your blood. If you hold your breath, your body continues to use oxygen – and produce carbon dioxide – forcing you to eventually inhale.
You can’t hold your breath forever!
Neither can fish, though they don’t have lungs.
Instead, they have gills.
These delicate structures serve the same purpose as lungs, allowing for gas exchange, but they draw oxygen from the water directly.
Healthy gills are red because they’re filled with oxygen-carrying hemoglobin.
According to Erin Spencer at the Ocean Conservancy, “Gills are branching organs located on the side of fish heads that have many, many small blood vessels called capillaries. As the fish opens its mouth, water runs over the gills, and blood in the capillaries picks up oxygen that’s dissolved in the water.”
Gills only function in the presence of water moving over them, and only then can they carry out the same gas exchange as your lungs do with every breath.
Remove a fish from water, and it can’t breathe. It’s like depriving you of air: you’ll start to suffer brain damage after a few minutes and you’ll quickly die.
In fact, though athletes like free divers can learn to hold their breath for more than three minutes, “Permanent brain damage begins after only 4 minutes without oxygen, and death can occur as soon as 4 to 6 minutes later.”
Free divers train constantly to increase the time they can hold their breath, but even the best of them have just minutes.
Think about that: 8 to 10 minutes without air will most likely result in brain damage and death for a human being. Rare cases in which cold-water drowning occurs can allow for much longer times without oxygen. But for the most part, the University of Michigan Transplant Center reports that after 10 minutes, recovery is unlikely as brain damage is likely to be extensive.
Those numbers are basically the same for fish, despite their less complicated brains.
How Long Can a Fish Live out of Water?
While exactly how long a fish can survive out of the water varies quite a bit if we include rare species like mudskippers and lungfish, the simple answer for most game species is measured in minutes.
Longer than four minutes in the open air will stress a bass of any kind, redfish, specks, snook, trout, salmon, and other popular game species, so it’s important to return them to the water quickly.
As you’d expect, proper handling and the individual biology of each species matters a lot. But air and water temperatures play a massive role.
Colder water slows a fish’s cold-blooded metabolism, giving it more time before it needs to absorb oxygen and release carbon dioxide.
Trout are very sensitive to being out of the water for longer than 60 seconds.
For instance, Danny Mooers says that trout can only survive for about four minutes without oxygen.
That makes sense: freshwater species like brown and brook trout are extremely sensitive to being removed from the water as they need abundant oxygen for their basic biological functions, and without it, they start to die very, very quickly.
If returned to the water within 60 seconds, Mooer reports, trout tend to be just fine, especially if water temperatures are below 60 degrees Fahrenheit.
60/60: that’s the rule for trout. No longer than 60 seconds out of the water, if the water temperature is 60 degrees F.
If water temperatures are warmer than that, or if it’s a particularly hot day, or if the fight lasted longer than usual, you’ll have less time to save your trout.
While bass can live for as long as 10 minutes in the air, the odds that they suffer irreversible harm is high.
For largemouth bass, a much tougher species than trout, you have a maximum of roughly 10 minutes in ideal conditions. “Ideal conditions” include cool water temperatures and a fish that was caught shallow without much of a struggle.
That’s good news.
It’s a pretty simple task to land, unhook, snap a pic, and weigh a bass in just a minute or two, and typically they’ll be just fine if you do your part to handle them correctly.
Just keep two things in mind.
First, whatever fish you catch that’s intended for release needs to be handled gently and returned to the water as quickly as possible. High water and air temperatures, long fights, and fish hooked in water deeper than 10 feet have less time out of the water before they start to experience dangerous stress.
Barotrauma, a result of a rapid ascent from deeper water, can injure fish, too, decreasing the time you have to release them.
This red snapper shows signs of barotrauma; it needs to be returned to the water as quickly as possible.
Second, even long stays in a live well can be lethal, especially if oxygenation is poor and the water in your live well isn’t 60 degrees or colder.
Post-tournament mortality is a serious issue, and live wells contribute to incredible stress, greatly increasing the odds of mortality in bass released after the final weigh-in.
Final Thoughts
There’s no one-size-fits-all answer to how long a fish can survive out of the water.
Instead, there are some general guidelines, modified by air and water temperature, hooking depth, and the length of the fight.
In general, it’s best to get fish back in the water as soon as you can, and in any case in less than 60 seconds if you want to ensure its survival.
Source: usangler.com