Every recreational angler in every part of the country must at one time or another release fish. Minimum size regulations require many anglers to release sub-legal-sized fish or “shorts.” Rivers, lakes, and reservoirs are areas where catch and release are particularly important. The increasing popularity of recreational fishing has led to the problem of too many people, too few fish. In some areas, only catch-and-release fishing is allowed. The increase in recreational anglers is not just limited to inland fisheries. Marine recreational angling is having a great impact on certain fish stocks as well. One of the primary means of allowing all these anglers to continue fishing and maintain healthy fish stocks is catch and release. Catch and release, whether it is voluntary or required, must be done properly if it is to succeed in having the fish survive. This fact sheet should help anglers to release fish properly to increase the likelihood that the released fish will survive.

Why Catch and Release?

With the cost of a typical fishing trip, the uncertainties of success, and the appeal of a fish dinner, why should anglers want to adopt the practice of catch and release? Aside from certain regulations, such as bag limits or size limits, there are a number of good reasons for releasing a portion of the catch alive.

First, catch and release offers a sensible way to extend the fishing trip after a reasonable or legal catch limit has been reached. If the trip involves a guide or charter service, catch and release can prolong an enjoyable recreational opportunity, giving anglers more value for their money.

Second, several recent studies have suggested that as anglers gain expertise in a particular fishery or fishing technique, they often develop an interest in “limiting their kill instead of killing their limit.”

Why Do Hooked Fish Die?

Fish that are caught and released may die for several reasons, but the two primary causes are stress and wounding. Stress results from the fish fighting after being hooked. Internally, the physical exertion causes an oxygen deficit in the tissues, forcing the muscles to function anaerobically (without oxygen). This causes lactic acid to build up in the muscle tissue, and then to diffuse into the blood. Lactic acid acts as an acid in the blood, causing the pH of the blood to drop. Even slight changes in pH can cause major disruptions of the metabolic processes, ultimately killing the fish. If the fish is quickly released, its blood pH usually returns to normal and the fish will be unaffected. Some fish, after a long tow, may appear to live once released, but the imbalance in the blood chemistry may kill them as late as three days after being caught. In most cases, the means of preventing this type of mortality is to not keep the fish in action for a long period of time, unless the intent is to keep it.

The other primary cause of mortality is wounding by the hook. Injuries caused by hooks can range from very minor to lethal. The degree of injury is dependent on the location of the hook wound. Higher mortalities will occur in fish that are hooked in the gill or stomach areas, while lower mortalities occur in fish that are hooked in the lip, jaw, or cheek areas. Baited hooks are more likely to result in a gill or stomach hooking that artificial lures. Treble hooks, for obvious reasons, will result in more puncture wounds and subsequently higher mortalities. Barbless hooks facilitate release and decrease “out-of-water” time, but for reasons yet unclear, may not significantly reduce mortality, especially when used with bait.

There are other kinds of physiological stress that can lead to higher mortalities in released fish. Fish may not be able to adjust to changes in pressure or to higher surface water temperatures. Also, when a fish is handled or comes in contact with dry surfaces, such as landing nets or dry hands, its mucous layers – commonly called slime layers
– may be partially removed, presenting an opportunity for bacteria or pathogens to invade the skin.

Sources:

Klauber, A. 1992. Catch & Release. In: Nor’easter: Magazine of the Northeast Sea Grant Programs. Fall/Winter 1992.

Malchoff, M.H., M.P. Voiland, and D.B. MacNeill. 1992. Guidelines to Increase Survival of Recreational Sport Fish. Cornell Cooperative Extension Fact Sheet.

How to Release Fish

Releasing Fish. Do it Right

Whether you intend to catch and release fish or not, knowing how to properly release fish is a good skill for every angler to acquire. You may want to release a fish that is too small to keep, or you may have to release fish because of size or species regulations regarding the type of fish you happened to catch. If you plan to catch and release fish, use barbless hooks as this makes releasing the fish much easier, and never use treble hooks. Also, keep a pair of needle nose pliers handy.

The first thing to observe is how the fish is hooked. If the fish has swallowed the hook, the best thing to do is cut your line as close to the fish as possible without taking the fish out of the water. The fish has a much better chance of survival if you do this. The fish will likely digest the hook in a week or two. If you must touch the fish for any reason, wet your hands first. This helps to preserve the protective slime on the body of the fish. Failure to wet your hands may result in removing the slime resulting in the fish becoming infected with a fungus or other disease after release.

If the fish has not swallowed the hook, release should be easy. Leaving the fish in the water, use HookOff™ as directed. This may take a little effort if the hook is barbed and the hook has penetrated deeply. The fish may do some of the work for you.

If you have an exhausted fish after a long battle and intend to release it, remove the hook, wet your hands, and hold the fish in the current with the head pointing upstream. Grip the fish just above the tail fin and gently push it forward and backward to open the gill plates and aerate the gills. The oxygen in the water should revive the fish after a few moments. Allow the fish to gently swim away of its own volition. Wait for it to seem fully revived especially in heavy current.

A few other items to note:

• If a fish has been accidentally hooked in the fin, back or other portion of the body, remove the hook as quickly as possible trying, not to damage the fish any more than necessary.
• Avoid putting your fingers into the mouth or gills of a fish. This can fatally wound them by breaking a gill or causing other excessive bleeding. Fish also have teeth that can cause injury! The hook could also come out unexpectedly in your finger.