Does Catch And Release Hurt Fish? The Studies

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Article Categories: Fishing | fishing tips
Article Tags: Catch and Release

The catch and release of Game fish has been practiced for over a century by anglers across the globe. It was provisionally devised to prevent certain species from disappearing in waters that were heavily fished.

In more recent times, many game fisheries and rivers have been converted to a complete or partial catch and release system to provide longevity to stock.

However, there is often a debate as to whether the catch and release of fish in these waters actually hurt the fish and is it ethically right?

This article seeks to help you understand what the science says regarding catch and release fishing. We will take you through some facts, theories and actual results from reputable case studies.

We will also detail some catch and release best practices to help reduce fish mortality rates.

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Mortality Rates & Factors | Mortality Rate Studies | Do Fish Feel Pain | Catch & Release Tips

 

Does Catch and Release Kill Fish

The short answer is yes. Catch and release does kill fish. What we really want to understand is:

  • What percentage of fish die from catch and release?
  • What factors play a role in reducing the percentage of fish that die from catch and release?

We will dig into each of these.

 

Factors That Increase Fish Mortality Rates

 

Temperature Of Water

Warmer water temperatures, particularly for cold water species play a major role in mortality rates. Warm waters stress fish out, and mortality rate studies show that as the water warms up, stress on the fish is more likely to kill it. Therefore avoiding fishing in warm water times, or at a minimum in the hottest parts of the days can drastically improve fish mortality rates. This is particularly true for trout, salmon, and steelhead. If waters are approaching 65 degrees F (18.3 C), then the fish are going to be much more prone to death. Warmer waters tend to have less oxygen available to the fish,

 

Duration Of The Fight

The longer a fight with a fish is, the more energy it expends, and the more stress is put on the fish. Studies show that shorter fights lead to better recovery, and longer fights lead to higher mortality rates.

 

Time Out Of Water

The longer a fish spends time out of water, the more likely it is going to die. This is why “keep ’em wet” is so popular among catch and release fisherman. When taking a photo, responsible anglers will never lift the fish high, and will limit the time out of the water substantially, or will simply elect to never lift the fish above the water. Bigger landing nets help with this a lot.

 

Handling Of The Fish

This category can be broken up into many parts. Handling the fish includes picking up a fish with your hands, the surfaces that the fish come in contact with, the release and pulling out of a hook, and allowing fish time to revive/recover in a safe location. Fish that touch dry hands, gloves, non rubber nets, dirt on the ground, ice, or really anything other than the water, will experience damage to their protective layers. Fish that get turned upside down, or squeezed too hard, or poked in the gills, eyes, or other areas will have higher mortality rates. This is why proper fish handling is so important. We will go into tips regarding this later.

When fish go through a long fight, they may also need time to revive and recover in a safe area, like large landing net where they can stay under water and the current won’t sweep them down stream. Properly reviving fish can lead to much better survival rates.

 

The Species Of Fish

Simply put, some species are capable of handling much more pressure. Trout, salmon and steelhead are prone to death and are far easier to kill than warm water species like Bass, Pickerel, Perch, and others. Some ocean water fish are extremely delicate, while others are extremely resilient. There are too many species to discuss here, but it is worth knowing how sensitive the fish species is that you may be catching in the water you are fishing.

 

Biological Factors & Location

Fish that have encountered disease, injury, recent breeding, illness, bad water quality, or even fish in closed ecosystems in specific lakes, or high elevations can have wildly different mortality rates. All of these factors can be difficult to understand or control, yet play a major role in mortality rates.

 

What Percentage Of Fish Die During Catch And Release?

We have compiled several studies for your reading as well as summarized our thoughts on these studies.

A 2005 meta study (a study that looks at multiple other studies to come to a conclusion) concluded that the average catch and release mortality rate was 18%. This study indicated that the species varies these average numbers widely. Read the study here.

A  study in Montana, predicts that around 20% of Trout that are released, die from stress or injuries sustained from the ordeal of being caught. According to the study, this figure does fluctuate pretty substantially when considering how the fish were caught, and several other factors.

Another study that looked at fish caught in a bass tournament concluded that over 40% of fish died within 6 days of being caught and released. It is worth noting that tournament catch and release could play a role in increased mortality. Read the study here.

A study on striped bass in North Carolina determined a mortality rate of 6.4% for released striped bass. You’ll notice this is a smaller number, likely due to striped bass being a bit of a more resilient species.

You’ll also hear about deep sea fish having extremely high mortality rates simply because bringing them to lower pressure water ends up killing them.

Summary:

Catch and release does have an impact on the environment, as catch and release seemingly kills somewhere between 5%-30% of fish when solid catch and release best practices are being followed. Trout and salmon are on the higher end of mortality rates and more resilient fish are on the lower end. Many factors play a role in catch and release mortality rates, but even anglers that follow all best practices will be hurting and killing fish over time.

Simply put, anglers need to be aware that even catch and release fishing has an impact on the environment, and effects can be limited by following best practice, not fishing during certain times, and limiting the amount of fish and pressure being put on a water system. Anglers should keep in mind that a limit of 2 fish for example from an angler spending an hour on the water may actually be making less of an impact than fishing a stream all day and catching and releasing 15-30 fish. Always keep waterbody regulations and conditions in mind.

 

Do Fish Feel Pain?

Whether fish feel pain is a debate with conflicting arguments. Those that oppose catch and release state that fish share many neurological structures that humans do that relate to pain perception. When the blood chemistry of a fish caught by rod and line has been analysed, hormones and blood metabolites associated with stress are high.

Studies by the University of Edinburgh (Rose, J. The Neurobehavioral Nature of Fishes and the Question of Awareness and Pain. Reviews in Fisheries Science, 10, 1 – 38, (2003) involved injecting bee venom and acetic acid into the lips of rainbow trout and their behavior was then analysed. The results showed that the fish responded by rubbing their lips along the sides and floors of their tanks in an effort to relieve themselves of the sensation.

The lead researcher in the study wrote, “Our research demonstrates nociception (the detection of painful stimuli) and suggests that noxious stimulation in the rainbow trout has adverse behavioral and physiological effects. This fulfils the criteria for animal pain.”

A more recent study from the University of Wyoming in 2014 states that this type of behavior may demonstrate a chemical sensitivity rather than pain and that the evidence for pain sensation in fish is ambiguous.

To counter this argument, again, the study from the Edinburgh University added morphine to the venom / acid injection to some different fish. These fish, acted a lot calmer than the fish that had no morphine, which suggests pain of some type was felt by the fish with no morphine administered.

Some research has concluded that fish may feel some degree of pain but not in the same way as humans do. These studies point-out that fish lack other neurological structures that humans have which suggests the pain perception may be different.

In summary, research suggests that the catch and release of fish, does cause pain, to fish but what is unclear, is to what extent.

 

So Is Catch and Release A Bad Thing?

The answer to this question is that it depends on what way you look at it.

In some situations, 20 out of 100 fish dying because of being caught is obviously not good. However, it is better than 100 out of 100 fish dying if all fish were caught and killed either for the table or by rule.

As we said at the beginning of this article, catch and release was only introduced, as it was a way to sustain fish populations. Without it, there would potentially be no fish to catch eventually due to diminishing stock numbers.

In the 1930’s, a famous outdoorsman, named Lee Wulff, quoted “game fish are too valuable to be caught only once.” Lee, any indeed many others at the time, concluded that if game fish were going to survive in the future then they shouldn’t all be killed once caught.

Simply put, always follow the regulations of the water body you are fishing. There are limits and rules created to help sustain fish populations and minimize impact on the ecosystem. When practicing catch and release, make sure to follow proper catch and release practices. Be an advocate for the environment you are fishing in, and do as much as you can to protect it. Don’t lose sight that even catch and release fishing has an impact on the environment.

 

How Can You Decrease Mortality Rates in Catch and Release Fish?

Unfortunately, as we have detailed in this article, mortalities cannot be totally avoided with catch and release fish. One thing that is true, however, is that mortality rates can be decreased by following some simple best practice when angling. This best practice is detailed as follows:

 

Use Barbless Single Hooks

The less damage you inflict on the fish’s mouth when caught, the less chance of infection and permanent tears that can really hinder the fishes ability to eat and grow. Single, barbless hooks are the most fish friendly hooks you can use to minimise damage yet still get the fish on the bank. A barb will allow anglers to pull out a hook in a much smoother fashion which will reduce time above water, damage to the mouth, and damage to the rest of the fish associated with holding it to pull the barb out.

Anglers will often take a regularly barbed hook, and use forceps to simply pinch the barb. This is an easy way to turn a barbed hook into a barbless hook. The very few fish you may lose from not having a barb, is worth the fish you will save over time utilizing barbless hooks.

Watch this video on debarbing hooks:

 

Be Prepared Before Starting to Fish

You will be surprised on the amount of anglers just show up to a water, cast out, and are caught totally unprepared when they have hooked the first fish of the day.

Be sure to have everything ready and organized before you start fishing. This includes landing net, unhooking equipment (forceps), camera (if you need a photo), your hooks were de-barbed before casting,  you have an area to safely land the fish, and that you have a clear plan to land the fish and release it as safely as possible.

Having everything in an easy to access position will avoid unnecessary time out of the water for the fish and will avoid potential harm of a fish flopping around on the bank whilst you sort yourself out.

 

Use Sufficient Fishing Tackle

It seems a no-brainer that you need to use sufficient tackle for the fish you are fishing for. But again, you will be surprised on how many anglers fail on this simple point. Use a rod with the highest weight you are comfortable with, and leader and tippet of the highest weight that will allow you to catch fish. This enables an angler to reduce the time of the fight of the fish, which studies show will greatly impact the survival rate of the fish. The faster the fish gets to net, the more likely it is to survive.

Many anglers love to fish lighter tackle as it can be quite fun, but keep in mind that hooking into a larger fish can lead to a longer fight, and therefore more stress on this fish. Whether you are fishing a fly fishing rod, telescoping rod, spin rod, or ocean rod, choosing a rod strength that can handle a bigger fish, may make it easier to land the fish faster.

 

Use The Heaviest Leader / Tippet Possible

This is a bit of a repeat of the above section, but important to reiterate. Use the heaviest leader and tippit possible to fool fish. This will have several impacts:

  • Enable the angler to “play” the fish less, and bring them to net quicker. Studies show this improves mortality rates.
  • Reduce the number of broken lines on fish, which leaves fish with line, hooks, and sometimes weights in their mouths. This can lead to mortality as well as pollution of the waterway.

 

Use a Rubber Landing Net

Again, this seems like a no-brainer, but we still see anglers not using one. Using a landing net supports the whole body of the fish when lifting it out of the water, which put less strain on the mouth and head of the fish than if it were to be just lifted straight up with the rod or hand.  In addition, a net allows an angler to leave the fish in the water, and with water flowing through its gills while pulling a hook out. It also gives a safe place to revive a fish if necessary.

We always recommend rubber nets over non rubber alternatives. Rubber has proven to be more forgiving to the fish, and reduces damage to the fish, which improves survival rates. Rubber nets tend to be more expensive, but we believe this is worth the expense.

Summary: Use any net over only your hands. If you can, please invest in a net with rubber netting.

 

Reduce Handling Time

Once the fish is caught and out of the water, the timer starts ticking. It is really important to get the fish back into the water as soon as possible to help improve its survival rate. Remember, when the fish is out of water, it is being starved of oxygen. If this is prolonged the fish will simply suffocate and die. Minimize time out of water as much as possible. It is pretty simply to release a fish without it ever leaving the water if you have a landing net. If you need to take a picture, make sure the camera is ready, lift the fish only a couple inches above the water, and immediately put back in the net or water. Reducing time out of water will greatly increase fish survival rates.

Before handling, always ensure you wet your hands to help keep the protective layer of slime on the fish’s skin intact.

 

Keep the Fish Wet & Don’t Wear Gloves

As stated in the previous point, it is good practice when the fish is on the bank to keep water going over the fish to help protect it. Keep fish in the water as much as possible. When handling a fish, remove any gloves, and ensure your hands are wet. This will keep protective layers on fish as intact as possible.

 

Be Careful How You Handle Your Fish

To help keep mortality rates down, handling really should be kept to a minimum. Only handle fish if you really need to. If you do handle one, always ensure your hands are wet, and never use a towel, glove, or a cloth to hold a fish.

If you are holding a fish up for a camera shot, always keep as low to the ground as possible and keep the fish over water so if it slips out, it simply lands in water. Never squeeze a fish too tight, and avoid contacting eyes and gills.

 

Be Careful When Returning Your Fish

When returning fish to the water it is important that this is done delicately. The fish should be placed in the water in an upright position and held lightly until it regains the strength to swim off comfortably. If the fish does not move when you initially place it, you should stay with it, keeping it in an upright position with water running through the gills to revive it. Allow the fish to regain energy, which may involve waiting for several minutes.

For more hints and tips on good practices when catch and release fishing, check out this great short video from Wyoming Game & Fish.

 

Final Thoughts

In answer to the original question of “Does Catch and Release Hurt or Kill Fish?” – we can safely say yes it does.

To what degree is dependant upon a wide variety of factors, and it is clear that proper catch and release best practices will yield the best results.

Max DesMarais
Max DesMarais

Max DesMarais is the founder of Hiking & Fishing. He has a passion for the outdoors and making outdoor education and adventure more accessible. Max is a published author for various outdoor and marketing websites. He is an experienced hiker, backpacker, fly fisherman, trail runner, and spends his free time in the outdoors. These adventures allow him to test gear, learn new skills, and experience new places so that he can educate others. You can read more about him here: hikingandfishing/about