|Most fisheries management agencies do not recommend deflating
the air bladder.
"Fizzing” or releasing the pressure from the gas bladder is sometimes used to facilitate release of undersized
fish. "Fizzing," when done correctly, is a process where gas is released from the gas bladder of a fish
by inserting a needle in the side of the fish and puncturing the gas bladder. Many anglers who practice fizzing are
actually puncturing the stomach. In actuality, it is the pressure in the gas bladder that must be released.
A fish that is unable to remain upright in the water because it is severely stressed and/or has an
over-inflated gas bladder, stands a poor chance of surviving if released. While helping a fish regain
its ability to return to the bottom of the lake, many fish that are "fizzed" end up dying within a few days
of release, from the stress of being caught and handled. There is also the likelihood that when you
insert the needle into the side of a fish you will damage internal organs such as the kidney or intestines.
a perch is quickly brought up from depth, the stomach is forced out through the mouth as the gas bladder
expands from a decrease in pressure as the fish is brought to the surface.
There are two major different
types of gas bladders in fishes: physostomous, in "primitive" fishes and physoclistous,
in "derived" fishes. Your understanding of lake trout physiology as related to the air bladder is correct.
Lake trout are among the generalized fishes known as Physostomi, which have a direct connection (pneumatic
duct) between the air bladder and digestive tract. This duct facilitates the direct passage of air in
either direction. Typically, this group of fishes fill the air bladder by gulping air form the surface
and release air from the bladder by “burping.”
Physoclistous gas bladders, however, do not open to the
mouth, so the fish has to let gas in and out of the bladder using a very complex little patch of blood
vessels that absorb or let go of gases from the blood. Fishes with these bladders include bass, perch, and sunfish.