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CPR for Fish!

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Published on: May. 2, 2006

Last revision: Nov. 29, 2010

Catch-and-release makes good sense. It provides more fish for more anglers to catch more often. But, catch-and-release itself has a “catch.” If people don’t handle fish properly, the fish won’t survive after being released.

That’s why fish managers, including this old fisheries biologist, like to think about CPR for fish. CPR doesn’t mean giving the fish mouth-to-mouth resuscitation—imagine that! Instead, it stands for Catch, Pamper and Release. Pampering, or taking good care of the catch before releasing it, helps ensure its survival.

CPR is necessary for both voluntary catch-and-release and for when regulations require anglers to release fish they catch.

Voluntary catch-and-release is more common than you might think. It’s a modern philosophy that’s evolved as fishing has become more of a sport and less of a means of putting food on the family table.

Sport anglers enjoy the process of finding, fooling and catching fish. To increase the prospects for future enjoyment, they release their fish to, as they often say, “fight another day.”

Surveys show that many anglers who target bass, trout and muskie release most of the fish they catch. They might keep the trophy of a lifetime, but they are just as likely to snap a photo of it and return it to the water.

Many anglers are even releasing catfish and crappie, typically thought of as food fish. It’s the fun and satisfaction of successful fishing they seek, not the flesh of the fish.

Tournament fishing has done much to spread the catch-and-release philosophy. Tournaments that end in a fish-fry have become exceedingly rare.

Almost all bass and walleye tournaments require anglers to keep fish alive so they can be released. They even deduct points if a fish is dead or near death at the weigh-in. This requirement has led to innovations in livewell design and tournament weigh-in procedures that better protect fish until they can be released.

Fishing regulations often require catch-and-release. Some areas that receive a lot of fishing pressure or that are being managed to protect or rebuild fish populations have areas or seasons in which only catch-and-release fishing is allowed.

Fish shorter than the legal length limit also have to be released immediately after being caught. It’s important for anglers not to disregard undersized fish as “shrimps,” but to treat them as fish that have not yet reached the legal limit. They may someday grow to be trophies. Their chances of growing larger are reduced, however, unless they are provided CPR.

The procedure for effective catch-and-release is similar for most species.

Avoid Stress

What usually kills or fatally injures fish is the combination of stress they experience during capture, hook removal and handling. Temperature, the amount of oxygen available and the length of time between catch and release also come into play.

Anglers should strive to minimize stress on fish during capture by landing them quickly, before they exhaust themselves with fighting. A fish that comes in completely worn out has less chance for survival. That’s why it’s important to match your tackle size and line strength to the species you are targeting. It’s a fact that you can land large fish on ultra-light lines, but the lunkers will have lower survival rates after being released.

The best method for releasing fish is one that you are familiar with and have practiced. You can use a landing net or you can grab the fish’s lip between your thumb and forefinger. If you know you’re not going to keep the fish, it might be better to free the hook with needle-nose pliers or forceps while the fish is still in the water.

When handling fish, keep fingers away from the gills and eye sockets.

It’s OK to snap a picture of a fish before releasing it, just be careful not to drop the fish on the floor of a boat or on the ground. When measuring a fish, wet your hands and the measuring board prior to laying the fish on it and don’t let fish come into contact with any dry surfaces. You want to avoid disturbing the slime or mucous covering on the fish’s body that protects the fish from infection.

Remove hooks carefully so that you don’t injure the fish’s gills or internal organs. If the fish has swallowed the hook or the hook is deeply embedded, cut the line rather than trying to force the hook out.

In some cases, you can use wire-cutters or the cutting portion of needle-nose pliers to cut the barb from the hook, allowing easy removal. It’s easy to replace the hook with another. Often, anglers who expect to release fish flatten the barbs of their hooks. The hooks don’t pull out as long as line is kept taut, but they slip out easily when it comes time to release the fish.

If a legal-size fish is deeply hooked or there is excessive bleeding, consider keeping the fish and making a good meal of it.

Never stringer a fish that you plan to release. Stringers damage a fish’s gills.

When you release a fish do it carefully. Don’t just toss it. It might be stunned by the impact with the water, or it could land on rocks or sticks.

When releasing an exhausted fish, hold it upright by its tail and move the fish very slowly forward and back until it recovers enough to swim away on its own.

Water temperature dramatically affects the survival rate of released fish. In spring and fall, when water temperatures are less than 80 degrees, properly handled bass often have survival rates over 90 percent, if immediately released, or even under delayed-release situations, such as bass tournaments.

However, as water temperatures climb above 80 degrees the chances of bass survival decrease sharply. Missouri Department of Conservation fisheries biologists cooperated with Mississippi State University to assess survival of bass that were caught, weighed in and released by anglers during summer tournaments. Release survival was less than 50 percent, even when anglers did all they could to pamper the bass.

The high mortality rate seems to be due to the combined effects of handling, confinement and high water temperatures, and the presence of largemouth bass virus. Warm water in livewells provides an environment under which this and other fish pathogens can thrive and rapidly infect healthy fish. Nearly all of Missouri’s large lakes have tested positive for largemouth bass virus.

Water temperature is also a key factor in catch-and-release survival of cool- and cold-water fish such as trout, muskies or walleye. Walleye studies have shown that release survival rates decrease at temperatures above 70 degrees.

During warm-water periods, all tournament organizers should consider alternatives to the standard weigh-in format. Several muskie tournaments in Missouri have combined digital photography and on-the-water witnesses to verify catches so fish can be released immediately. Fish also require oxygen, which they get from the water. A fish out of water is like a person with his or her head underwater.

Try holding your breath while you are unhooking, photographing or transporting a fish, and you’ll understand the oxygen deprivation a fish might be experiencing. Make every effort to release fish quickly. Keep the camera ready so you can take pictures quickly.

Fish kept in overcrowded or poorly aerated livewells also suffer from oxygen deprivation.

A constant flow of fresh, cool, aerated water through the livewell will help maintain a healthy environment for the fish. Because cooler water holds more oxygen, and fish in cooler water consume less oxygen, some anglers and researchers recommend adding ice to the livewell. However, it is important not to cool the livewell water more than 10 degrees below the surface temperature of the lake to avoid creating a temperature shock for the fish.

A livewell additive that can reduce stress is common, uniodized table salt. Add one-third of a cup of salt per 5 gallons of water in the livewell. This is similar to the concentrations used in many hatchery transport vehicles.

The best way to pamper a fish that you’re not going to keep is to reduce the length of time between catching and releasing it. Any confinement, whether the fish are held in a livewell, a weigh-in bag or a pickle bucket, can reduce survival rates, especially when the water is warm.

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