Recently I watched a YouTube segment produced by Lindner’s Angling Edge. It was in question-and-answer format, with Al and James Lindner fielding a variety of fishing-related questions submitted to the company’s various social media platforms.
For those unfamiliar, the Lindners created In-Fisherman magazine, and after selling it years ago developed Lindner Media. Angling Edge is one of its many products.
Most of the questions fielded by the two related to the nuts and bolts of fishing tactics and location. But one question really sparked my interest, as it’s been a concern for many years. It’s that of barotrauma in fish taken out of relatively deep water.
Barotrauma, as defined by Wikipedia, is “the physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with, the body, and the surrounding gas or fluid.” As it relates to fishing, barotrauma can occur when removing a fish from deeper water, where its swim bladder expands due to the atmospheric pressure change, so much so that in cases the fishes’ stomach is pushed out its throat. In this state it can be difficult, if not impossible, for the fish to return to its original depth as it doesn’t have the strength to counter the buoyancy of the expanded swim bladder.
In general, species most affected by barotrauma are warm-water and cool-water species such as bass, pike, muskies, walleyes and panfish. Depths beyond 30 feet, basically one atmosphere, are where it’s likely for barotrauma to be an issue.
Trout and salmon have a pneumatic duct that connects the swim bladder with the mouth, allowing them to “burp,” serving as a relief valve of sorts.
The barotrauma dilemma has been known for many years. I recall attending a Professional Walleye Trail tournament on Lake Erie nearly three decades ago where biologists from the Ohio Division of Wildlife demonstrated the “fizzing” technique used to deflate the swim bladder of walleyes taken from deep water. Fizzing involves using a hypodermic needle to puncture the fishes’ swim bladder so it can decompress, in theory allowing it to return to its original depth. However, fizzing must be precise, otherwise vital organs can be damaged, and there’s the risk of infection from the use of dirty needles. From a practical standpoint, also, one must wonder how well the fish can then function with a punctured swim bladder, if in fact it only delays the fishes’ demise.
As the Lindners pointed out in their response, barotrauma is more of an issue today than it was just a few short years ago, particularly at this time of year when fish tend to be found in deeper water. Modern electronics allow anglers to locate fish at these depths, and many have the skill to catch them in depths of 40 to as much as 90 feet. If you’re going to fish these extreme depths, plan on harvesting any of the fish that you catch and limit such a catch.
It’s been my experience that smallmouth bass taken from 25 to 30 feet swim back down fine if they are released immediately. Holding them in a livewell, where they struggle to remain vertical and use up valuable energy, is problematic. Which brings up another issue, that of tournament anglers holding fish taken from deep water in livewells, transporting them for miles over rough water to the weigh-in sight. It’s a common occurrence on Lake Erie and other large bodies of water, and the mortality rate at some events is sad.
Whereas the smallmouth bass we catch typically come from 20 to 30 feet of water, walleyes often come deeper, from 30 to 40. If the fish show no signs of barotrauma, bleeding gills and/or distended stomachs, we’ve released them with confidence they’ll be OK. But in many cases the fish are destined for the frying pan. The same goes for crappies we’ve taken from such depths.
For the sake of our fisheries, it’s important to understand barotrauma in fish, and how to tailor our efforts accordingly.