North Dakota Game and Fish Department fisheries personnel encourage anglers to keep fish caught from depths of more than 25 feet, rather than practice catch-and-release.

Scott Gangl, Game and Fish fisheries management section leader, said while catch-and-release is often encouraged under the right conditions, fish reeled in from this depth will likely die if released.

“Fish caught from deep water likely won’t survive because of the extreme change in water pressure,” Gangl said.

Change in water pressure will cause the swim bladder to expand, Gangl said, which means fish can no longer control balance. In addition, Gangl said other internal injuries will likely happen, such as ruptured blood vessels or internal organs.

In severe cases, the swim bladder can rupture, and the gas inside it fills the body cavity, putting pressure on the fish’s internal organs — sometimes even pushing them out of the mouth and anus.

While bloating and bulging eyes is often a sign that barotrauma has occurred, some fish do not have swim bladders but could still be injured, so a lack of noticeable bloating does guarantee the fish is fine.

This can happen in any deep water body, Gangl said, but it is especially noteworthy for this time of the year in Lake Sakakawea.

“As water warms during summer, fish tend to move to deeper, cooler water,” he added. “This is particularly true for walleye in the big lake, where walleye follow their primary forage of rainbow smelt to deeper depths as summer progresses.”

Anglers fishing at least 25 feet deep should make the commitment to keep what they catch, and once they reach their limit to stop fishing at that depth.

“Our simple message is for anglers to keep fish that are caught from these depths, or to fish in shallower water when practicing catch-and-release,” Gangl said.