Reducing Catch and Release Mortality

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Reducing Catch and Release Mortality

From “The Marine Scene” – Florida Sea Grant

Recreational anglers often fish for the sport of it, choosing to release what they catch. Many fish that are caught must be released because for many fish species, the size and number that may be caught by an individual is regulated (see Florida Saltwater Fishing Regulations for Florida’s recreational saltwater fishing regulations, and Florida Freshwater Fishing Regulations for recreational freshwater fishing regulations.) However, there is some concern that fish that have been hooked and released may not survive their stress or injuries.

There are several things that the recreational angler can do to increase the chance that fish that they catch and release will survive. The most common causes of release mortality are stress during the capture process and injuries from the hook or the angler. As with humans, physical exertion results in lactic acid buildup in the fish’s muscles and blood which can result in muscle failure or death. Anglers can reduce fish exhaustion by using the proper weight tackle for the size of fish they are targeting, by landing the fish quickly, and, if possible, by leaving the fish in water while releasing it.

To reduce stress or injury caused by handling the fish, anglers should either not handle the fish at all (removing the hook using a de-hooking tool), or should use wet hands. If a towel or gloves must be used, these should also be wet. The slime layer on a fish’s body serves many protective functions for the fish, including anti-bacterial functions. If that slime layer is removed, the fish will be more vulnerable to infection and possibly also predation. If the fish is to be held up for a photograph, holding the fish horizontally (in a natural swimming position) rather than vertically will reduce the risk of damaging the fish’s internal organs.

To reduce injuries caused by hooks, barbless and circle hooks can be used. Barbless hooks are shaped like standard j-hooks, but have the barb removed. The advantage of barbless hooks is that they can be removed quickly and easily. A study on catch rates of snappers and groupers did not show any difference between barbed and barbless hooks. For most saltwater fish species, circle hooks result in higher catch rates and lower catch mortalities when compared to j-hooks. Anglers who are accustomed to fishing with j-hooks will have to modify their hook-setting technique when using circle hooks in order not to pull the hook out of the fish’s mouth. Circle hooks are designed not to catch in the fish’s gut or throat, but to catch the corner of the mouth as the fish swims off after taking the bait and hook.

If fish do become gut-hooked, the recommendation is that the angler cut the line as close to the fish’s mouth as possible, rather than trying to remove the hook. The swallowed hook will decay fairly rapidly, and the fish’s body may actually cover it with tissue while the decay process occurs, allowing the fish to heal as the hook disappears. (Don’t us stainless steel hooks). When deep sea fishing, anglers should be aware that they can increase grouper survival rates by properly venting the fish before releasing it. The swim bladders of fish that are brought to the surface from depth may burst. This causes gases to accumulate in the fish’s abdomen, giving it a very swollen belly. The stomach may be pushed forward and may actually stick out of the fish’s mouth. You can find good info on proper fish venting techniques by going to Deflating Fish.

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