For the past couple of years, North Dakota Game and
Fish Department biologists have put forth a concerted effort to inform state
anglers about a condition called “barotrauma,” which can occur in fish caught
from water depths of more than 25 feet.
It’s particularly a concern in North Dakota this time
of year in Lake Sakakawea and Devils Lake, when walleye anglers typically find
good numbers of fish in 25 to 40 feet of water.
We get a good number of questions on this issue, so
I’m including a summary here of common questions posted on the
Game and Fish website at gf.nd.gov
.
What is barotrauma?
“Barotrauma” is the term used to
describe any of the number of injuries, or trauma, a fish may receive from
rapid changes in atmospheric (i.e. barometric) pressures. For fish caught by
anglers, these rapid pressure changes occur when fish are reeled to the surface
from deep water. Most internal injuries are not visible to anglers, but one
obvious symptom of barotrauma is the over-inflated swim bladder, which will
push the fish’s stomach out of its mouth and make it impossible for the fish to
swim back to the depth from which it came.
What is “fizzing,” and does it really
work to increase fish survival?
Fizzing, or venting, is the procedure of
puncturing a fish’s swim bladder with a sharp object, like a hypodermic needle,
to release the excess gas and deflate it. While fizzing can relieve some
symptoms of barotrauma, the few studies on this matter have shown that even if
a fish swims away after it’s been fizzed, it may have lasting injuries that
lead to death at a later time.
I’ve read that reeling in a fish really
slowly can help. Is that true?
In most cases, no. Some fish species,
like salmon, pike or catfish, have a pneumatic duct that they can use to
release, or “burp,” gases from their swim bladder. But walleye, perch and bass
do not have this duct. They regulate gases in their swim bladder through their
bloodstream, which takes quite a long time. So when most anglers consider
reeling a fish in slowly (say 3-5 minutes) to allow them to release gas from
their swim bladder, it’s not nearly slow enough to be effective.
What does the Department suggest an
angler do when it comes to this issue?
The Department strongly recommends that
if you are fishing in waters deeper than 25-30 feet, you should make a
conscience decision to keep everything that is caught, up to the daily limit, or
spend your time fishing in shallower depths where barotrauma is not an issue.
How about the few lakes in North Dakota
that have length minimums in place?
Most of the waters in North Dakota that
have length limits do not have much for deep water to start with. In the few
lakes that have deeper water and length restrictions, like Jamestown and Pipestem reservoirs, anglers
should simply avoid fishing the small areas of deep water unless they intend to
keep the fish they catch.