More and more anglers are using the “catch and release” fishing practices method. There has been a rise because both anglers see catch-and-release as a way to protect wildlife and fisheries managers require folks to do it. Many people use catch-and-release, but not many people know how much mortality is caused by the practice or how different catch-and-release methods may affect the amount of mortality.

Luckily, the rise in catch-and-release fishing has happened at the same time as the rise in study that looks into catch-and-release fishing. It’s true that most of the studies done so far have been on individual species, but based on what we know so far, we can make some general suggestions.

Physiologically, catch-and-release is upsetting, but stress and death can be kept to a minimum by following some general catch-and-release rules. For quick recovery, the gear should be right for the species being angled. It might be possible to cut down on the time it takes to release fish by using barbless hooks and circle hooks. Fewer fish should be exposed to air, and they should be set free quickly. If you’re not sure whether to release a fish, you should look at how deep it was caught, where the hook was, and how much it bleeds.

When done right, catch-and-release can work and cause little harm to the fish, so it should be promoted. The way different species react to catch-and-release methods is different, though, so more study is needed to make rules that are specific to each species.

Getting Started

In the last few decades, catch-and-release fishing practices has become very popular. Only 5% of anglers polled in an examination of recreational fishing in Ontario in 2000 said they did not use catch-and-release in some way (OMNR, 2003). People can do catch-and-release on their own or because the law requires them to. For many types of fish in Ontario’s seas, size limits are used as a way to keep everybody in check. There are times when fish have to be returned because they are too small, too big, or in a protected slot size from being caught. People who fish can also choose to practice catch-and-release as a way to protect wildlife.

One of the main reasons why catch-and-release methods are being used more and more by anglers and fisheries managers is the belief that fish that are returned stay alive. When fish are freed after being caught, they usually swim away without any damage, which leads to this conclusion. According to study, most fish die some time after being released (Muoneke and Childress, 1994). This means that fish that look healthy when they are first released may later show signs of harm or distress caused by catch-and-release practices. More research is needed to find out how many animals die during catch-and-release and what factors may affect their chances of surviving. This is because deaths could affect how well catch-and-release works as a management method.

People who fish and people who run fisheries often don’t realize how much death is caused by catch-and-release methods. A look at 118 catch-and-release studies (Appendix 1), which included more than 120,000 fish, showed that 16.2% of the fish that were caught and released died. Because of this, a lot of fish may die after being caught and then returned, even though many anglers may think that their actions have no effect on the fish population. Additionally, many fishermen will keep fishing after they’ve caught their limit because they believe that they will release any more fish they catch. However, they often don’t think about how many fish will be killed by this action.

The goal of this review is to bring together all the current information about catch-and-release fishing and give some tips on how to reduce the number of deaths that happen because of this method. Even though the number of tournaments in Ontario is growing, this review doesn’t look at the unique problems that come up with competition practices. But sometimes, results from studies that only looked at tournaments are shown when they can be used in fishing situations that aren’t tournaments. Because tournament fishing is so unique and is becoming more and more popular, tournament rules should be looked over again.

Factors That Affect How Well Catch-And-Release Works

How The Body Reacts

Several studies (Beggs et al., 1980; Gustaveson et al., 1991; Tufts et al., 1991; Ferguson and Tufts, 1992; Cooke et al., 2003a) have tried to find out how the bodies of fish react to catch-and-release methods. A lot of general answers can be drawn from these studies. Long hours of play can wear you out. This is marked by acidity because white muscle that isn’t getting enough blood flow releases protons into the extracellular fluid (Tufts et al., 1991). In particular, this makes the amount of lactate in the blood rise and the pH outside of cells fall (Tufts et al. 1991). When the fish is caught, the gill lamellae collapse because they are exposed to air. This stops almost all gas movement. This makes the amount of CO2 in the blood rise and the amount of O2 in the blood fall (Ferguson and Tufts, 1992). The heart rate goes up when you do hard exercise or breathe in fresh air (Cooke et al., 2003a). The stroke volume goes down and the cardiac output goes up. It is pretty clear how fish’s bodies react to catch-and-release methods, but not as much is known about how these sub-lethal stressors affect fish over time.

The sub-lethal stress that comes from catch-and-release can lead to slower growth, fewer babies, and a higher risk of getting diseases and germs. The amount of hookings had an effect on the growth of smallmouth bass (Clapp and Clark, 1989). More hookings meant slower growth afterward. Over the course of four months, Mason and Hunt (1967) looked at how long deeply hooked rainbow fish lived and how much they grew. They found that the growth of fish that were released did not slow down significantly among those that lived to the end of the trial. This was true even for fish that still had hooks in them. Booth et al. (1994) looked at how catch-and-release helped reproduction and found that there wasn’t a big difference between Atlantic salmon eggs that were angled and eggs that weren’t angled. On the other hand, Cooke et al. (2000) found that angled largemouth bass, which care for eggs as parents, were more likely to leave their broods and be eaten by other fish. In the same way, Suski et al. (2003) found that smallmouth bass are less able to protect their young when they are turned away from their nest. This means that there is proof that catch-and-release may make some species grow and reproduce less successfully.

Aside from putting animals through sub-lethal stress, catch-and-release methods may also hurt them, which might not kill them right away but could have bad effects. Hooks, for instance, can hurt the gills, jaw, stomach, and eyes. These injuries could make it hard for the fish to move, eat, or reproduce, which could eliminate fish that were healthy before.

Type Of Hook

There is a lot of difference between species in how different types of gear affect catch-and-release mortality, but there are some things that can be said in general. In general, using circle hooks to catch fish tends to lower the number of fish that die. Most of the time, the point of a circle hook is not parallel to the shank like it is on a standard J-style hook (Figure 1). A study found that circle hooks are less likely to get stuck deeply. However, there is some evidence that bluegill may be more likely to get eye damage (Cooke et al., 2003b). A study by Cooke and Suski (2004) looked at how well circle hooks worked and found that they cut general death rates by about 50%, but the results were different for different species.

To lower the number of fish that die during catch-and-release, barbless hooks are often suggested instead of sharp hooks. In fact, to cut down on catch-and-release deaths, Manitoba and Alberta have laws that say only barbless hooks can be used for fishing in those states. Barbless hooks make it easier to remove the hook, which cuts down on the time needed for handling and the number of deaths that happen as a result (Cooke et al., 2001). According to Schaeffer and Hoffman (2002), barbless hooks unhook fish much faster than barbed hooks. However, the same study showed that hunters caught 22% more fish with barbed hooks than with barbless hooks. Similarly, using hooks without barbs has been shown to greatly lower the death rate of fish (Taylor and White, 1992). Some people also think that hooks without barbs cause less damage to tissue. So, even though barbless hooks are generally better for fish, fishermen might not want to use them because they think it will make it harder to catch fish.

Using Real or Fake Food

Some research has also been done on how the type of bait affects the death rate for catch-and-release fish. Striped bass are much more likely to die when hooked on natural baits than when hooked on fake baits (Wilde et al., 2000). In the same way, worm-baited hooks are eaten deeper by bluegill than fake lures and flies, which leads to more deaths (Siewert and Cave, 1990). When hooking walleye that were caught on live or fake leeches, the death rate was 10% for live leeches and 0% for artificial ones. Using leeches also led to deeper hooking (Payer et al., 1989). For smallmouth bass, the death rate is 11% when minnows are used and 0% when spinner lures are used (Clapp and Clark, 1989).

More and more scented fake bait is being used these days. Fish may attack scented artificial baits in the same way they would attack real bait, which could lead to more deaths. Schisler and Bergersen (1996) found that hooking mortality was much higher when fish were caught on scented artificial bait than when non-scented artificial bait was used. This supports the idea that smell matters. Dunmall et al. (2001), on the other hand, found that scented fake bait had no effect on the death rate of smallmouth bass that were caught and then released. These studies show that using organic bait and maybe scented fake bait leads to deeper hooking, which raises the risk of injury during hook removal and puts the fish out in the open air for longer while the hook is being removed. Using fake food can lower the number of fish that die after being caught and released.

Where to Hook Up

Catch-and-release fish deaths are affected by where the hook is placed. If you catch and release white seabass, the location of the hook had a direct effect on how many of them died, and all of them died from hook damage to the visceral area (Aalbers et al., 2004). Another study found the same thing: 56% of largemouth bass that were hooked in the stomach died. The death rate for fish hooked in other places was about the same as the death rate for fish that were not hooked at all (Pelzman, 1978). Dextrase and Ball (1991) found that lake trout that were deeply hooked were more likely to die from being caught. Also, northern pike that were deeply hooked were more likely to die (Dubois et al., 1994). Schisler and Bergersen (1996) found that rainbow trout that were hooked in the gill arches or stomach died much more quickly than rainbow trout that were hooked on the skin. This was because of the intense bleeding that happened where the hook was placed. Based on these studies, it is clear that fish that are deeply hooked are more likely to die.

Deep hooking makes fish more likely to die, but it’s not always clear whether it’s better to cut the line on a fish that is deeply hooked or try to remove the hook, which could hurt the fish more and expose it to more air. Aalbers et al. (2004) looked at the growth and survival of white seabass up to 90 days after they were caught. They found that fish that were released with their hooks in were more likely to survive than fish that had their hooks taken out, but their growth was slower. Death rates were 65% when hooks were taken out and 41% when they were left in. 39% of the fish in this study that were freed with their hooks still in place were able to get rid of them by the end of the study. However, there wasn’t much damage to the hooks that stayed in place. That’s similar to what Mason and Hunt (1967) found when they looked at what happened to rainbow fish up to four months after they were released after the hooks were taken out. Only 11.5% of the fish that had their hooks taken out lived after being released, while two-thirds of the fish that had their hooks taken out did. What’s more, more than half of the fish that lived with hooks still in their bodies had lost them by the end of the study. Schill found in 1996 that cutting the line on deeply hooked rainbow trout cut their death rate from 58% to 36%, and by the end of the study, 60% to 74% of fish that were freed with hooks still in their bodies had been able to get rid of the hooks. New ideas say that taking out the hook through the gills of fish like bass and walleye might be able to lower the number of deaths caused by deep hooking (Strange, 2003). However, as of now, there have not been any real-world studies that show this fishing technique to be useful. So, even though there haven’t been many studies that look at how deep hooking affects mortality, it looks like, for some species, mortality can be lowered by letting fish go with the hook still in place after being deeply caught.

Bleeding

Many years ago, Myers and Poarch discovered that the amount of bleeding in hooked largemouth bass was linked to both death and the position of the hook. Out of 19 fish that were bleeding, 47% died, but only 20% of fish that were not bleeding died. When fish were hooked in the mouth, only 1% bled, but 48% of fish hooked in the throat and 50% of fish hooked in the lungs bled. The Arctic grayling study also found a link between the amount of bleeding and the position of the hooking. However, there was no link between death and the amount of bleeding (Clark, 1991). Schisler and Bergensen (1996) found that the amount of bleeding was strongly linked to death in rainbow fish. Their model said that the chance of dying went from 16% when there was no bleeding to 40% when there was a lot of bleeding. It has also been found that bleeding in cutthroat fish is strongly linked to death. Dead fish were 6.5% of the time and fish that bled were 52.8% of the time (Pauley and Thomas, 1993). All of these studies show that fish are more likely to die if they are bleeding. Because of this, hunters should think about keeping fish that are bleeding a lot.

How Deep The Grab Is

It is possible for fish to get hurt when they are caught and quickly brought back from deep water. When the pressure drops too low, the gas bladder can get too inflated and not be able to sink when the pressure is released. This can lead to gas embolisms, internal and/or external bleeding, and death. The swim bladders of freshwater fish are mostly one of two types. Catfish, esocids, trout, and salmon all have a tube that connects their swim bladder to their food canal. It takes longer for fish like bass, walleye, perch, and most panfish to empty their swim bladders because they don’t have a connecting duct. These fish can get rid of gas and change their buoyancy more quickly. So, different fish species are more or less likely to die from depressurization, but it can still be a major cause of death (Kerr, 2001).

To free fish that are having trouble with depressurization, a method called “fizzing” has been created to deflate their swim bladders artificially by poking them with a sharp object. Kerr (2001) looked at “fizzing” and said that it should be avoided because it can do a lot of damage. He also said that fishing in deep seas (5–6 m) should be limited if fish are meant to be released. Also in 2001, Kerr looked at a number of different methods besides “fizzing” that could be used to free fish caught in deep water. For these, a retrievable weight or underwater cage was used to lower the fish back to the depth at which they were caught so that they could be set free. Few studies have been done to see how well these options work, but they are still suggested over fizzing. Catch-and-release fishing for species in deep water should not be done to avoid deflation.

The Temperature

It looks like the death rate for catch-and-release fish is directly linked to the temperature of the water, with the death rate going up at very high temperatures. Muoneke (1992b) looked at the hooked mortality of bluegill over the course of the year and found that it was higher in the summer when the water was warmer. But this study didn’t look at other factors, like differences in how fast animals ate or their reproductive state, which could have led to more deaths in the summer. In the same way, as water temperature rose from 8°C to 16°C, the death rate for cutthroat fish rose from 0 to 8.6% (Dotson, 1982). When looking at all the deaths of black bass that happened during tournaments, Wilde (1998) found a strong link between water temperature and both deaths before and after the competition. According to research from walleye tournaments, the number of deaths goes up with the temperature of the water. This means that tournaments should only happen in the spring and fall (O’Neil and Pattenden, 1992) or when the water is cooler than 15.6°C (60°F) (Boland, 1994). The physiology of Atlantic salmon after exercise was studied by Wilkie et al. (1997) at 12°, 18°, and 23°C. They found that physiological healing was slowest at 12°C, but there was a lot of death at 23°C. This finding shows that warmer temperatures help people get better, while very high temperatures make people more likely to die.

Nuhfer and Alexander (1992) found that brook fish that were hooked and bleeding from the gills or throat died more often when the water temperature went up. It has also been found that smallmouth bass (Cooke and Hogle, 2000), largemouth bass (Gustaveson et al., 1991; Meals and Miranda, 1994), and striped bass (Nelson, 1998) are more likely to die when the water temperature rises. If you catch and release striped bass, you may find that their death rate is linearly linked to air temperature but not to water temperature. This means that the temperature of the air may be more important for survival than the temperature of the water. The results of these studies show that catch-and-release fish deaths go up with temperature, so extra care should be taken when fishing when it’s very hot outside.

There have been similar worries about letting fish go that were caught at an angle while ice fishing and were exposed to cold weather. Some people think that eyes and gills can get hurt when they freeze on very cold days. Still, research that looked at the catch-and-release survival of walleye during ice fishing didn’t find any damage or deaths caused by the cold (Ellis, 2000). Because of this, fish should only be out of the water for short periods of time when ice-fishing. Longer periods of time may not kill or hurt the fish.

What Kind of Landing Net

Even though a lot of hunters use landing nets, not much research has been done on how damaging they are or which types of nets hurt fish the least. In general, landing nets shouldn’t be used too often because they are thought to hurt fins more and remove the protective mucus layer, making the fish more likely to get sick. Barthel et al. (2003) looked at how different types of landing net mesh affected bluegill injuries and deaths. When they measured the effects of netting 168 hours after capture, they found that fish that were caught without a net died at a rate of zero, while fish that were caught with a net died at a rate of 4 to 14%. Also, the pectoral and tail fins were scratched more, and the skin was disturbed (scale and mucus loss). People were hurt and killed more by the knotted mesh types than by the rubber or knotless mesh types. The four types of mesh were rubber, knotless nylon, fine-knotted nylon, and large-knotted nylon. This means that injuries (and deaths) can be cut down by only using landing nets when they are needed to safely land and handle fish to avoid mechanical damage. If you have to or want to use a landing net, though, it’s best to get one made of rubber or knotless mesh.

When handling big fish like muskellunge, it’s often best to use cradles to keep the fish from getting too stressed. Cradles are usually made of mesh that is strung between two poles so that it can fit the fish’s body (Figure 3). Using cradles keeps fish in the water while hooks are taken out. A tape measure can also be built into the cradle so that the fish can be measured while it is still in the water. There haven’t been any scientific studies that look at the benefits of using cradles for big fish, but most people agree that they are helpful (Smith, 2001).

Air Exposure

Ferguson and Tufts (1992) found that the length of time rainbow fish were exposed to air had a direct effect on how many of them died. When rainbow trout were chased for about 10 minutes, 88% of them survived. But when they were exposed to air for 30 seconds, that number dropped to 62%, and when they were exposed to air for 60 seconds, it dropped to 28% (Ferguson and Tufts, 1992). A study by Cooke et al. (2001) looked at how handling time affected damage and heart problems in rock bass. There were no deaths from exposure to air, but fish had bradycardia (a slower heart rate) while they were in the air, and their cardiac output went up when they were put back in the water. Cardiovascular output and arrhythmia (irregular heartbeat) went up when fish were chased for 30 seconds. It took 2 hours for fish that were exposed to air for 30 seconds to fully recover, but it took 4 hours for fish that were exposed to air for 180 seconds to fully recover (Cooke et al., 2001). These studies show that being exposed to air is bad for animals and show how important it is to cut down on handling time and air exposure during catch-and-release.

Time to Recover

Catch-and-release has an effect right away, but fish may not fully recover physically for a while after being set free. Aging caused tilted muskellunge to get acidosis, which took them 12 to 18 hours to recover from, according to Beggs et al. (1980). Wild Atlantic salmon had similar healing times. After being active for about 10 minutes, they had extracellular acidosis that lasted for about 4 hours and blood lactate levels that stayed significantly high for at least 8 hours (Tufts et al., 1991). It was found by Wydoski et al. (1976) that hooking rainbow fish raised the amount of chloride in their blood and caused changes in their plasma osmolarity that went away within 8 hours (Wydoski et al., 1976). Cooke et al. (2003a) looked at how the hearts of largemouth bass responded to simulated fishing events and found that it took about 135 minutes for the heart factors to return to the levels they were at before the exercise. The time it takes for fish to heal after catch-and-release may help explain why deaths often happen after the fish have been released.

How Big The Fish Is

People think that the size of the fish affects how many die during catch-and-release because bigger fish are harder to handle, so more deaths may be expected as the fish gets bigger. To back up this idea, Meals and Miranda (1994) discovered that largemouth bass caught in tournaments were much more likely to die (29% vs. 9%) if they were longer than 18 inches than if they were between 12 and 14 inches. In the same way, Wilde (1998) did a meta-analysis of deaths related to black bass events and found a weak but positive link between fish size and initial mortality. But the fact that bigger fish died more often in these studies could be because they were crowded and needed more air while they were being stored in live wells, not because of a natural link between fish size and death. Some studies have also looked at the link between fish death and size and haven’t found any significant link (Titus and Vanicek, 1988; Schill, 1996). Note that the studies we’ve talked about here only looked at death rates and fish sizes within the same species. They haven’t looked at the differences between species. It’s hard to figure out what intraspecific studies mean because any link seen between fish size and death could be due to things that are different between species, like how they eat and how their mouths look. On the other hand, it seems fair to think that big species like muskellunge and pike might be more likely to die than little species. When these big fish are played with and handled for longer amounts of time for pictures, their bodies are upset for a longer time after fishing. So, extra care should be taken when handling big fish to keep them from getting hurt or dying.

Rules For Catch-and-Release

So far, most study on catch-and-release has looked at how different species react to things that might cause them to die. There are, however, a number of general trends that are becoming clear because so many studies have been done so far. While it’s important to be careful in applying species-specific results to other species, the following suggestions are good general ways to lower the death rate from catch-and-release for most species based on what we know so far.

Tips for Angling

People should use circle hooks because they make deep catching less likely.

Barbless hooks are better because they are easy to take off, which cuts down on the time needed for handling.

It is not a good idea to use live or organic bait because it makes deep-hooking more likely.

A lot of people should use fake hooks to catch fish.

Leave your fishing lines alone, because if you do, they are more likely to deeply hook a fish.

The fishing line should be right for the type of fish that is being sought. This will keep lines from breaking and cut down on the time spent playing.

If you plan to release your catch, don’t go fishing when the water is very hot or very cold.

Caught a Fish

To keep fish from getting tired, angled fish should be brought back as soon as possible.

Most of the time, fish should be caught by hand.

If a landing net is needed, it should have no knots and be made of soft rubber if possible.

One thing that should be thought about is using a landing cradle when catching very big fish like muskellunge.

Taking Pictures And Handling a Fish

As much as possible, keep fish in the water to keep them from coming into contact with air.

Do not stick your fingers in the eyes or through the gills.

Heavy fish can hurt your head and back if you hold them by the jaw.

Hold a big fish horizontally and support its body so that the parts inside don’t get hurt.

To handle the fish, wet your hands or put on wet cloth gloves.

As little as possible, have your camera ready before you land the fish.

Get pictures of the fish while it’s in the water if you can.

Getting a fish-free

Make sure you have longnose pliers on hand to back out the hook.

Take the hook off quickly while the fish stays under the water.

Cut the line and let the fish go as soon as possible if it is badly hooked.

If you leave stainless steel hooks in fish for a long time, they will rust faster.

Depressurization

If you want to return your catch, don’t fish in water that is deeper than 5 to 6 meters.

If you’re not sure whether to return a fish or not, think about how deep it was caught.

As soon as the fish is caught, let it go.

Avoid artificially deflating your swim bladder (called “fizzing”).

Revival

Hold the fish straight up so it faces the stream if there is one.

If the water isn’t moving, move the fish back and forth slowly until its gills start moving normally again and it can keep its balance.

Let the fish swim away when it starts to fight.