October 26, 2021 — Deep-water rockfish reeled quickly to the surface often emerge from the water with eyes and organs bulging like alien beings—due to the sudden change in pressure—a condition known as barotrauma.

Now new research shows that if fishermen return fish to their natural depths quickly, their bodies return to normal and they can survive any ill effects. The research focused on cowcod and bocaccio, two historically overfished rockfish species caught off the coast of Southern California. They were returned to the depths using special descending devices that are now standard for many recreational fishermen.

Prior to this research and the use of descending devices, it was widely assumed that deep-dwelling rockfish could not survive catch and release due to their extensive barotrauma injuries. “We now know that these deep-dwelling rockfish species can survive,” said Nick Wegner, a research scientist at NOAA Fisheries’ Southwest Fisheries Science Center and lead author of the new research. “That is good news for the fish, and good news for the fishermen who go to the trouble of trying to release them properly.”

The research was published in ICES Journal of Marine Science. Scientists used acoustic transmitters to track released cowcod and bocaccio for up to a year on an underwater seamount approximately 40 miles off the coast of San Diego, California. They were captured at depths of 75 to 183 meters, or about 250 to 600 feet. By tracking the fish for extended periods, researchers found that most fish survived beyond 30 days. Of those fish that died, 40 percent died beyond the typical 2-day tracking window used in many fish survivorship studies.

Read the full story at NOAA Fisheries