Updated: Feb 12
As the dog days of summer are upon us the fish will move to deeper cooler waters for more comfortable conditions. When fishing deep in the hot summer months it is common to have fish caught in the depths struggle to return once released. This is due to the rapid changes in pressure when coming up from the depths and how it impacts their swim bladder.
A fish is able to change its depth in the water column by inflating and deflating its swim bladder (think of it like a balloon inside them). Inflating their swim bladder makes them more buoyant and rise while deflating their swim bladder will make them less buoyant and sink. To stay at a given depth they inflate their swim bladder such that it matches the pressure of the water around them. In deep water this means the swim bladder will be under a lot of pressure! When anglers bring fish up from the depths too quickly the pressure on the swim bladder decreases. When you decrease the pressure of gases they expand. This means the swim bladder expands rapidly, putting stress on the other organs around it, and making the fish a lot more buoyant. It can even expand so much as to come out their throat or rupture (this is really bad). Once this happens fish have a hard time returning back to the depths and will often be seen floating after release for some time until the fish can re-establish equilibrium.
There is much controversy in the fishing industry about how to handle this situation. One of the ideas is to "fizz" the fish. Fizzing the fish involves sticking a needle into the swim bladder to deflate it and allow the fish to re-regulate on its own as it returns to the depths.
While we agree this will help them return back to the depths we do not agree with the practice as a whole. Yes the fish will be able to return back to bottom but what are the other consequences? Sticking a needle into a fish and damaging one of its most essential organs can't be good for it. Imagine if someone poked a hole in your stomach, how long would it take to heal, would there be other complications? You bet there would be. The same is true for fish. In addition to this, who carries sterile needles with them in a boat? So not only are their organs being damaged but there is a huge risk of bacterial infection from fizzing.
There are a few alternatives to fizzing fish that don't pose as big a risk to the fish:
Don't rush the fish up from deep water; let it come up on its own
Release the fish right away (and as fast as possible) after catching so the fish can return to the depths before the swim bladder starts impacting them
Put the fish in the livewell for a while (maybe a couple hours even) with sufficient oxygen until it gets itself back under equilibrium
Don't fish for deep fish
Weighted fin clips - Attach to the fish and bring them down into the depths before releasing
Whether or not you agree with our stance on this topic we encourage you to look out for the health of the fish and put this as a top priority. We make our decisions based on research (real studies not empirical evidence) and air on the side fo caution if ever in doubt. If evidence comes to light that there is no negative impact to fizzing fish on their health we will re-evaluate our stance. Some more sources for information on fizzing fish are below: