2023-May-23
Catch a Lake Trout in Deep Water? Think Twice About Releasing It!
During warm late spring and summer months, should a Lake Trout caught in deep, cold water be released? Anglers need to understand, before releasing their fish, how water pressure and temperature can determine the fate of the fish’s life.
Deep, cold-water species like Lake Trout swim at depths ranging from 35 feet (10.7m) to 65 feet (19.8m) during the warmer months. Swimming at these normal depths, the swim bladder (see diagram) in the fish’s body is regulating depth and buoyancy while water pressure is keeping the swim bladder small. When the fish is caught at these lower depths and is hauled to the surface, the water pressure declines causing the swim bladder to rapidly expand. This is called Barotrauma pressure shock.
photo: Great Lakes Fisheries Commission
The Trout will not have sufficient time to absorb the buildup of gas into its bloodstream. Even a slow ascent may be too fast for the fish to compensate for the changes in water pressure and temperature. Normally, in shallower waters, a fish can compensate for this by having time to burp or vent gas from its mouth. Otherwise, the fish becomes incapacitated and unable to control its equilibrium or balance which will likely lead to other fatal injuries such as bulging eyes or distended bellies (where gas from the swim bladder has escaped into the abdominal cavity). These gas-filled “floaters” will provide an easy meal for seabirds and other predators.
In conclusion, anglers targeting fish in deeper waters should keep what they catch until their limit is reached according to the restrictions set out in their fishing license. Once reaching their limit, the responsible angler should then stop and leave the fish for another day.
By Bill Steiss