Principle tenets of being responsible aquarists and fisherman is to be good stewards of the resources that we’ve been endowed. For aquarists this means sourcing sustainably caught or captive bred fish, and for fisherman this means releasing fish that are not suitable due to size, sex or a particular season.
For deep sea fishermen, catch and release is harder said than done because many of the fish caught and brought up from depths of 100 feet (30m) or more show signs of decompression problems, more commonly referred to as barotrauma by fishermen. The complications of Barotrauma are all due to the expansion of gas in the swim bladder which will cause the eyes to bulge and the stomach to pop out of the fish’s mouth, preventing the fish from being able to return to the depth at which it was snagged.
New tools called descending devices are now becoming available to deep sea fishermen that enable them to return the fish to the depths where the pressure reverses the effect of barotrauma, at which point the fish is released and it can swim off to be fished another day. It may be a misnomer to say the fish is “unharmed”, their bulging eyes and distended stomach surely feel a little bit of soreness from the ordeal, but at least they are returned in a good enough condition where the fish can survive its release, even if it is a little bit confused about its experience. [NPR]