Fish suffering from barotrauma are not a pretty sight–the eyeballs pop out of the sockets, the stomach protrudes out the mouth, and they become too buoyant to swim down to a safer depth.
Deep-sea fish often suffer from barotrauma–the sudden pressure change that causes the gas in the swim bladder to swell–when they’re brought up to the surface by fishers.
Fish suffering from barotrauma feel stiff, “just like an inflated balloon,” explained John Hyde, a program leader at NOAA’s Southwest Fisheries Science Center in San Diego. Most fishermen assume that these fish are goners, but that doesn’t have to be the case.
Hyde and Nicholas Wegner, a NOAA biologist and postdoc, have been studying new methods of helping rockfish (Sebastes) recover from the effects of barotrauma, as rockfish stocks have been severely overfished.
Their method involves using a SeaQualizer (link no longer active), a small, cylindrical device that has noninvasive jaws that lock onto the lower lip of the rockfish. The device is lowered into the water and is programmed to automatically release the fish once it reaches a depth of about 45 meters.
They have also used tools as simple as an upside-down milk crate to lower the fish to safe depths where the effects of barotrauma can largely be reversed. But, Hyde includes that “if you don’t get ’em down quickly, they’ll die.”
The issue of ‘recompression’ in fish will be a topic of discussion at the federal Pacific Fishery Management Council (PFMC) meeting today, November 5. The officials will begin to consider proposals that would give recreational fishers “credit” for releasing rockfish with a recompression device. These proposals would benefit both the fishers and the depleted rockfish stocks.
Recompression studies are still relatively new, and more long-term data is necessary to determine just how effective it is. However, underwater video footage does show that using recompression devices allows rockfish to achieve high short-term survival. “There’s no question that it’s better than letting them die,” said Hyde.
To learn more:
- Read this news focus from Science: Putting Rockfish Back Where They Belong
- Check out this study about recompression in rockfish, published in the Journal of Fish Diseases, here: Recovery potential of black rockfish, Sebastes melanops Girard, recompressed following barotrauma
Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.