Maximizing Survival After Catch-and-Release

Fish Facts
Support the abdomen when holding fish horizontally.
Support the abdomen when holding fish horizontally.

I always start my pond management seminars with three golden rules of pond management. They are 1) build it right, 2) stock it right, and 3) fish it right. Then I ask my audience, "Which rule is most often broken?" Most people guess "fish it right," which is the correct answer. This is because most pond owners fail to harvest enough small bass, which can cause the bass population to become too crowded, especially in southern ponds.

When pond owners do fish and harvest their ponds correctly, the flip side is that larger bass need to be released unharmed so they can grow larger. We know that harvesting fish results in 100% mortality, but we often wrongly assume that all released fish live to fight another day. When the mortality of released fish is greater than we think, it can lead to problems in our management efforts. In other words, catch-and-release does not work if fish do not survive the process.

As a management tool in public waters, catch-and-release fishing is particularly beneficial for conserving breeding populations, protecting long-lived species, and preventing overfishing. In your pond paradise, it is intended to allow medium-sized, fast-growing fish to reach larger sizes. Harvesting smaller fish frees up prey that can be eaten by medium-sized fish so that they can grow up big and strong.

Catch-and-release fishing is intended to allow a fish to be captured, released, and possibly caught again. This requires that fish are as fit after release compared to pre-capture, meaning that fish must survive the angling experience and be able to defend and support themselves. Unfortunately, the process of angling often causes stress and injury.

There are many potential stressors and injuries that may affect fish health. These stressors vary by duration and magnitude and are influenced by gear type, fight characteristics, environmental conditions, and post-capture handling and release practices. Physiological stress is of concern, as the process of angling causes an increase in Cortisol and lactate, a decrease in blood pH, and a whole host of other issues. Physiological impacts may include cardiac output and functionality disturbances, respiratory challenges, and diminished immune response, making a released fish more susceptible to bacterial, viral, or fungal infection.

The hooking location is critical. Although the bony mouth of most fish is armored and has few blood vessels, deep hooking in the throat or stomach can cause severe bleeding, gastrointestinal trauma, or other injury. Hooking a fish on the outside body (e.g., in an eye or body wall) can cause bleeding, infection, and blindness. Further, lifting a fish from the water requires the fish to support its weight out of the water. This can cause wounds to the body, organs, and spine. Finally, the abrasions caused by the angling process or handling can cause infection by bacteria or fungi.

Research has shown that catch-and-release mortality ranges from zero to 100% of released fish dying. This mortality can occur immediately after release or days to weeks later. Although mortality is unlikely 100% for most pond species, it is also unlikely to be zero. And you may not necessarily see the dead fish, especially in a pond with many turtles or other scavengers. Losing one or a few fish to angling mortality is not a big deal until that one fish is your prized 12-pounder. So, let's discuss how to improve the survival of released fish.

There has been extensive research directed at reducing release mortality in many species of freshwater and marine fish, and much of it can be condensed into three simple recommendations.

First, use the right gear. I know it may be fun to catch a 10-pound bass on a micro rod with 2-pound mono, and I too am guilty of attempting this feat. Unfortunately, the 45-minute fight that it takes to land the fish is very stressful to the fish. During the prolonged battle, Cortisol will accumulate, blood chemistry changes, osmoregulation is affected, and the fish greatly risks physical injury. If you use heavier gear, the fight will be shorter, but the fish will be less stressed and more likely to survive. If you have ever watched professional bass anglers during a tournament, you know that they land fish as quickly as possible, of tea within seconds. Sure, they are trying to get the fish in before it escapes, but there is also a hefty penalty for weighing dead fish!

Likewise, the type of lure or bait needs to be considered. Finesse baits like slow-fished soft plastics or live bait are much more likely to be swallowed, resulting in deep hooking that can damage the gills, esophagus, or stomach. I try to avoid finesse baits and live baits when possible. Using circle hooks with live bait can reduce deep hooking. Conversely, treble hooks can do a lot of damage by hooking the fish in multiple locations, often including the eye or gill arch. For these reasons, I prefer single hook lures that are actively fished to reduce deep hooking and prevent multiple injuries. You can even pinch down the barb to further reduce injuries.

Second, avoid hot weather. Research has clearly shown that bass die much more readily when the water temperature reaches 80 degrees or higher. Many other fish species likely also have temperature limits above which mortality goes way up. This may be due to the increased metabolism at higher temperatures, lower dissolved oxygen availability, or, more likely, both. If you fish when it is warmer, follow the other recommendations and ensure that the fish is stressed as little as possible.

Third, avoid prolonged air exposure. We all like to immortalize our big catches with a photo; however, taking a fish from the water for Facebook or Instagram can be very harmful. Fish are not designed to be in the air or to feel the full effect of gravity. Normally, the water medium provides support to the body. This support is gone when removed from the water, and gravity can take a toll.

This is especially true when lifting a big fish by the lower jaw.  I know it is a cool-looking photo, but please never hold a fish horizontally by the jaw without supporting the abdomen. This can cause serious damage. The effect of gravity on a large fish can include separation of the vertebrae and damage to internal organs. If you must pull a fish from the water, use both hands to support the head and abdomen. This is still not great for the fish, but it is certainly better than breaking the fish's jaw using its own weight.

Finally, it is essential that you limit air exposure as much as possible. Less than 2 minutes is a good rule of thumb, but avoid pulling the fish from the water altogether if possible. Not only is it bad for the fish to be exposed to drying and gravity, but you are also more prone to accidentally dropping the fish on the deck or bank, which can cause significant trauma.

Catch-and-release of larger fish can be accomplished using the least harmful fishing and handling practices. Using appropriate gear, avoiding fishing when the water temperature is hot, and minimizing air exposure will maximize the possibility of catching those fish again.

Dr. Wes Neal, an Extension Professor at Mississippi State, serves as the State Extension Fisheries Specialist and is passionate about educating the public on small lake and pond management. He is an avid researcher on topics ranging from farm pond management to sport fish genetics. Wes is the lead editor of Small Impoundment Management in North America, the only textbook on the subject. He loves to hunt and fish.

Reprinted with permission from Pond Boss Magazine