The following video explains barotrauma and several methods to properly release rockfish with barotrauma (and a pretty great rap video at 7:25!) :
Note: If you are catching a lot of rockfish in an area, particularly species which are threatened or endangered (See COSEWIC listings), the best thing to do is to move into another area.
With over 30 species in BC, Rockfish are commonly caught by anglers in the Pacific Northwest, and are often discarded as unwanted bycatch. These rockfish do not often survive due to barotrauma, however recent studies have shown that rockfish with barotrauma can survive if they are quickly returned to depth to allow recompression.
Barotrauma in rockfish is caused by a change in pressure when the fish is quickly brought from depth to the surface, which causes the swim bladder to expand. The expanding swim bladder can displace internal organs, resulting in bulging eyes and causing the stomach to protrude out the mouth. If rockfish with barotrauma are simply thrown back into the water, they will not be able to return to depth and will often just be left floating on the surface.