Up from the depths

Reeling up a fish from deep water can cause injuries

Montana Fish, Wildlife & Parks has developed recommendations for anglers to reduce trauma to fish that are caught in deep water and then released.  

Reeling up fish from the depths can result in barotrauma, which refers to internal and external injuries sustained due to the rapid decompression of a fish’s air bladder.  

Visible signs may include bulging eyes, protrusion of the stomach from the mouth and bleeding from the mouth or gills. Internal injuries may include hemorrhaging of organs, gas bubbles in bloodstream and vision damage.  

“Barotrauma can happen in any waterbody when fishing at a depth greater than 30 feet for walleye, yellow perch, burbot, crappie and bass,” said Jason Mullen, Region 4 fisheries program manager. “An example would be Tiber Reservoir. As the water warms up, walleye tend to move into deeper water and thus will be more prone to barotrauma if caught in 30 feet or greater.” 

The recommendations were developed by the FWP walleye workgroup, which includes fisheries biologists who manage walleye fisheries. The recommendations were then reviewed by other FWP fisheries managers. This is the first time FWP has issued barotrauma recommendations. Many nearby states have already issued recommendations, Mullen said. 

To reduce barotrauma and unintended hooking mortality of walleye, yellow perch, burbot, crappie and bass the following FWP makes the following recommendations: 

• Avoid angling in waters 30 feet or greater when planning to catch and release any walleye, yellow perch, burbot, crappie or bass.  
   

• Consider keeping fish if they exhibit visible signs of barotrauma (bulging eyes, protrusion of the stomach from mouth, bleeding from the mouth or gills). 
   

• Practice good handling procedures – minimize fish handling time, keep hands/fingers away from gills, keep fish wet and do not hold fish in live wells that you intend to release. 
   

• Do not vent fish (i.e. “fizzing”) or use fin weights. 

For additional information, please contact your local FWP fisheries biologist.