Free Falling: Fizzing Wild‐Caught Smallmouth Bass Results in the Inability to Control Buoyancy in Deep Water

Abstract

Fizzing, a somewhat controversial technique for mitigating barotrauma, uses hollow hypodermic needles to release gas from the swim bladder of fish. To isolate effects of fizzing, 106 smallmouth bass (Micropterus dolomieu) were caught from shallow water without barotrauma and tested to determine if they could effectively control their buoyancy after having their swim bladder fizzed or punctured by releasing them over shallow (10 m) or unsuitably deep (55 m) habitat. Depth and behavior were monitored with biologgers. Most fizzed (57%) and punctured (61%) fish were unable to regulate their buoyancy in deepwater, sinking to the bottom and appearing moribund. In shallow water, punctured smallmouth bass stayed higher in the water column (like controls), while many fizzed fish stayed on the bottom. Our results suggest that if smallmouth bass are fizzed and immediately released, precautions should be taken to ensure they are released in areas of appropriate water depths (< 10 m).