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Catch & Release

What constitutes success, what causes failure

by Michael Edwards

Attitude and Knowledge….the two most important things to the success of catch & release. With a conservationist attitude and the knowledge to implement that attitude, catch & release can be a strong tool to maintain the health of a fishery. Take away either, and catch and release can be a failure.  To bypass the article and go directly to the "to do" list for successful catch and release, follow this link.  However, I strongly recommend that you read the entire article and the attached studies.

The Tradition of Fishing

Fishing has been part of the human experience since before written history; from the seining of fish in the Red Sea, to the fast paced action of Sailfish in the Atlantic, to the stories of Tom Sawyer on the banks of the great Mississippi. Fishing can be described as the pastime that transcends all cultures, races, genders and ages.

Catching of fish is enjoyed by many as a pleasurable diversion from the humdrum of life while it is a means of subsistence for others. Eating of fish ranges from the level of delicacy to the level of improving one’s diet

These two events, catching and eating, have at times led to declines in fish stocks. And as a result, it is a major function of most of the conservation departments throughout the United States and beyond to provide guidelines and regulations that allow all citizens to enjoy a sustainable, properly conserved stock of fish.

A practice that has evolved as a commonplace event over the last 15-20 years is "catch & release". Although anglers have been practicing this process for centuries, it has only recently been discussed and analyzed by the scientific research community. The reasons for its current level of debate stem from many things, but perhaps the biggest factors are

  • the dramatic decline in certain fish stocks (Cod in Massachusetts and Salmon in the Pacific to name a couple)
  • coupled with the growth of the recreational angler population,
  • and a concern that if it is not implemented properly it may not achieve its maximum effects.

If you are not a catch & release angler, then this article may not apply to you (unless you wish to practice catch & release in the future). If you are currently a catch & release angler then you may learn some facts and results that will surprise you, and some that will downright shock you. I urge every one of you to take the time and read this article, the instructions on how to conduct a successful tournament, and the attached studies. Some of this is difficult reading, but it is important to learn how to be successful at catch & release.

Catch & Release

For those that are not familiar with "catch & release", it is what it says. "Catch" the fish and then "release" it at some point in the future for it to continue its course of survival. Some folks practice it as their only means of fishing. Others use the practice to determine which fish to bring home for food. Others practice it during competition or as they search for a "trophy". Whatever your reason for practicing catch and release, the goal is always to release the fish so that it might survive.

Herein lies the debate. How many of these released fish survive and what are the conditions that determine their ultimate survival after release? Unfortunately, the answers are not easy to come by and many more studies need to be done to determine the factual answers. But, one thing is for certain – if the fish is kept by the angler then it has no chance of survival. Another appears close to certain – if catch & release is not practiced properly it can result the death of the fish anyway.

A related question, but one that is not so obvious is the effect of the perception of catch and release. This will take a moment to explain. Most states have limits as to the size and number of fish that can be kept for each species (and the Federal Government sets limits on some saltwater species). These limits are established through estimates of what level of "culling" is healthy and sustainable for a fishery. Culling here is defined as the removal of fish from the population (i.e./ being kept by the angler). A certain level of culling is healthy to a population in that it limits the number of fish that need to compete for food and habitat. Nature has a way of culling through predatory relationships. Just as with hunting, people also participate in the culling process through limits imposed by the conservation agencies of our state and federal government. Yet, when it is perceived that many fish can be caught and released with little concern about daily bag limits then the angler must be especially concerned about the survivability of the fish which he/she is releasing back into the lake. If these fish do not survive, then that angler may in fact be over harvesting his/her allowable limit. This applies to all anglers – non-tournament and tournament alike.  Additionally, if released fish end up dying, floating  and washing up on shore, a public outcry will be heard (and a wonderful resource will be wasted).

So, as we go into the subject of catch & release studies one must always be mindful of the two most important success factors related to this practice – Attitude and Knowledge. With the attitude that you intend to implement proper conservation techniques and with the knowledge that allows you to understand the results of your actions, you can help to contribute to a healthy, sustainable fishery.

Factors for Successful Catch & Release

Although the answers for this section are far from certain, there appear to be a number of factors which significantly impact the success rate of catch & release. Studies for different taxonomic groups (types of fish) show that improper catch & release techniques can result in significant death of released fish. By eliminating the stresses to the best of one’s ability, the death rates can be as low as 1% (although many factors may cause the actual rate to be higher no matter how meticulously the techniques are applied). So, following proper fish handling techniques during the entire process of catching, transporting, and weighing will mean the success or failure of your catch & release practice.

Realized average death rates for immediate catch & release and transport catch & release will vary dramatically from species to species and are discussed at length in many of the attached studies.

The following factors have direct impact on the success of catch & release and some are discussed in more detail below:

Species of fish (anatomically)
Different species have different mouth construction and differing locations of vital organs in relation to their throat

Species of fish (voracity of feeding)
Some species "mouth" a bait, while others inhale and swallow quickly (may also depend on bait used)

Type of terminal gear
Relates to the techniques used when employing the angling technique (i.e. bobber fishing for sunfish versus trolling for salmon).  Some types of terminal gear are more conducive to deep hooking than others

Type of bait
Artificial or live, barbed or barbless hooks, single or treble hook.  Different types of baits cause different locations of hooking wounds

Anatomical location of hooking wound
Hooks in the mouth are seldom associated with hooking related mortality, yet hooks in the gills or throat are often fatal

Water temperature
Relates to the activity level of fish. Typically the colder the water, the lower the activity level of the fish.  The hotter the water, the higher the fish's level of activity and also the higher the stress experienced by the fish during capture, handling, and release

Depth caught at
Excessive depths can cause depressurization related mortality

Length of "fight"
Refers to the amount of time the fish is played at the end of the line
Time out of the Water
For some species, any time out of water will cause detrimental chemical changes on the gills that will effect survival.  For almost all fish, time out of the water that exceeds 60 seconds can be very stressful

1. Oxygen and Water temperature. If you are an "immediate" catch and release angler, then these factors may not have as much impact as those anglers that capture, transport and then release fish. Studies have consistently demonstrated that mortality increased with temperature, and lower mortalities at lower temperatures have been associated with lower metabolic rates and physical activity..

  • For immediate catch and release anglers it is important to be aware that the longer a fish is out of the water, the higher the risk that the fish will become oxygen starved. This will have different effects on different species, but it increases the risk of delayed mortality on all species. In some instances, like with Rainbow Trout, the fish should not be removed from the water at all. In other instances, like with Sailfish, the fish needs to be moved through the water after removal of the hook so that it can revive. With higher water temps comes a paradox…lower dissolved oxygen yet higher respiratory needs of the fish. With extremely low water temperatures (and air temperatures) comes the other end of the spectrum which can result in freezing damage to the fish’s gills, eyes and fins. The detrimental water temps differ for different taxonomic groups.

  • For transport catch and release anglers, the levels of dissolved oxygen and the water temperatures of your livewells are the two most important factors to the survivability of the fish. Improper operation of livewell aeration and fresh water pumps can result in significant death of fish. A general rule of thumb is that if the water temperature is above 70 degrees farenheit you should run your fresh water pumps and aeration pumps constantly while you have fish in the wells (since most livewell pumps are run from the cranking battery that is recharged every time that you run with the "big motor", this will not have any negative effects on the troll motor battery reserve power for bass anglers.  Check the wiring of your boat to confirm this).. Just because the fish are alive does not ensure that they will survive. Long periods of exposure to low oxygenated water will have seriously detrimental effects on delayed mortality.  If you carry the fish within a sack to the weigh-in scales, you may be placing additional stress on the fish by way of waste buildup and oxygen depletion in the sack water. These are stresses that can be eliminated through water replacement and limiting the amount of time that the fish are in the sack. Within the sack, it is important to have a lot of water in the sack at all times and to replace some of the water within the sack with the treated, aerated water that should be present at the weigh-in troughs.

2. Length of Fight – the longer that a fish is played on the line, the higher its risk of death due to chemical changes in the fish’s blood and cell tissues. During an extended fight on the line, a fish's blood chemistry changes to accomodate the increased needs of the fish's body during exertion.  Immediately after the extended fight, the fish' s body is virtually starved of oxygen.  By holding the fish out of the water for an extended time, or by placing it in a livewell with low oxygen levels, you are encouraging the buildup of waste within the fish's cell tissue.  This can have detrimental effects to the fish that will appear days later possibly resulting in delayed mortality.  It is extremely important to get the fish into well oxygenated water within seconds of such an extended fight.  Or better yet, use tackle that allows you to land the fish quickly thereby eliminating an extended fight.

3. Depth – the deeper the water that a fish is brought up from, the higher the risk of mortality. The depth ranges differ with each species of fish, but as a general rule if you are catching fish at depths greater that 30 feet then the fish will experience some level of depressurization stress.   What is it and how does it effect fish?   The fish's air bladder becomes over-expanded causing increased pressure on internal organs and restriction of blood flow.  This in turn and can cause certain gases to come out of solution in the bloodstream causing vessel clogging bubbles (similar to the bends).  The way in which this fish is handled relative to the other stresses listed will compound its risk of death. It is important to handle these fish with extreme care, or to avoid catching these fish if you intend on releasing them later.  Studies have shown that fish caught at extreme depths can have mortality rates of more than 70%, whereas the same species caught in shallow water with all other conditions unchanged may experience mortaility rates of 0%.  Lake trout are a major exception as they are physostomous and therefore do not experience over inflation of the air bladder.

4. Time out of Water Stress – studies have shown that the time out of the water for a fish plays a significant role in its survivability. Here the difference between 30 seconds and 60 seconds can be deadly to some species of trout. The time above 60 seconds can significantly impact other species such as black bass. Other species (certain catfish) are not nearly as sensitive to stress related to time out of water.

5. Terminal Tackle. The relationship of hook design and hook size to fish mortality is not a clear one. In many cases angler experience and the speed at which the angler "sets the hook" appear to have more impact on the damage done than the hook itself. One exception appears to be the difference between barbed versus barbless hooks. This appears to be related to the ability to remove a barbless hook more easily with less tissue damage, and it only appears to be a factor if the fish is hooked in certain areas (such as a deep-hook in the throat region). Tissue damage can loosely be associated with the amount of bleeding caused by removing the hook. The more bleeding, the more tissue damage. "Circle hooks" have recently been in the media, yet the results are mixed regarding their success. Generally, deep hooked fish that bleed will have a difficult time surviving after release. This needs much more study for proof, but use extra care with a fish that bleeds from hook penetration that you intend to release. Lots of fresh water and aeration within the livewell, or do not remove it from the water if you are immediately releasing it. 

The age old question..."Do I leave a deeply embedded hook in a fish's throat region, or do I remove it?" Studies seem to suggest doing both, leaving it in and removing it.  Obviously, you can only do one or the other so you must decide which to do.

It seems that if a hook is left in, it has the potential to block the fish's throat leaving the fish unable to swallow.  The shank of the hook effectively shifts up when food that is being swallow presses against it, thereby not allowing the food to pass into the fish's stomach.  The fish will eventually "spit" the food out of its mouth.  As you can guess, this may eventually lead to the fish starving to death.  

However, removing the hook  has the potential of creating more trauma to the hooking wound.  Through additional tearing of the throat region and internal organs, removing the hook may cause the fish to bleed to death.

If you feel that you can remove the hook without causing excessive bleeding, then attempt to remove the hook.  Here a de-hooking tool can be an invaluable device and every angler should have one on board their boat.  This is a device that slides down the hook's shank and into the hooking wound.  It "covers" the embedded barb, reducing the tearing when the hook is removed. 

However, if you find that you cause more fish to bleed when you remove hooks, then try a technique which is gaining popularity in the northeast.  Use long-handled cutting dikes (very long handles...10-12 inches) to cut the actual shank of the hook off leaving only the bend of the hook and the point imbedded in the fish.  This leaves less hook to rust and prevents the shank from obstructing the passage of food through the fish's throat.  If you use these cutting dikes, be careful not to cut the soft tissue of the fish's throat, yet be sure to cut as much of the hook shank and bend off as possible.   These dikes are available at most auto retail stores.

One study found that leaving deeply imbedded hooks with a length of line still attached in salmon and trout increase their chance of survival. Studies have shown that removal of deeply imbedded hooks in these species will most likely result in the death of the fish (most probably caused by the tissue damage done by forcing barbed hooks out and the resulting bleeding). However, cutting and leaving the hooks in has been shown to cause problems with survival in striped bass.  The jury is still out on this one, but the use of a de-hooker to remove the hook or the use of dikes to cut away the majority of the hook shank while leaving only the embedded barb appear to be to alternative courses of action.

6. Bait. Live bait versus artificial bait is not as clear as it once was. This may be due to the scented lures on the market now combined with new rigging techniques. In past studies it was usually found that live (or chunk) bait was more often swallowed by the fish resulting in a deep-hook with significant tissue damage. Today, many artificial baits appear to generate similar results if the angler is not quick to set the hook.

What to Do to Ensure Successful Catch & Release

The following are simple suggestions and apply to all anglers, from saltwater to freshwater. To learn more on how to specifically conduct a black bass tournament, read the instructions located at this link. By following the instructions faithfully, you will significantly improve the successful release and survival of the fish. By not following the instructions, you personally are putting that fish as well as that fishery at risk.

  1. First and foremost, know the species that you are targeting. The level of care and the survivability of a particular fish is significantly different from species to species. The attached studies go into detail about the survivability of each species (study not yet posted.  We expect to have it posted before August 21, 1999.  Please return to this section of the article after that date to read about survival rates for species ranging from sunfish to spotted seatrout :-)
  2. Second, keep the fish out of water as little as possible during the entire time that fish is in your possession. This time out of water is measured in seconds, not minutes. And for some species, it is risky to remove them from the water at all. If you are immediately releasing the fish, ensure that it is revived and swims off in a healthy manner under its own power.
  3. Third, take care with deeply embedded hooks (in the throat or gills).  If you choose to leave the hook embedded in the fish, remove any plastic and lead from the bait.   Then use long-handled cutting dikes to cut the actual shank of the hook off leaving only the bend of the hook and the point imbedded in the fish.  This leaves less hook to rust and prevents the shank from obstructing the passage of food through the fish's throat.  If you use these cutting dikes, be careful not to cut the soft tissue of the fish's throat.  If you choose to remove the hook, use a de-hooking tool (available at most tackle outlets) and use care so as minimize or eliminate any tearing of the fish's throat or gills when removing the hook.
  4. Fourth, ensure that any containment vehicle (i.e./ livewell) contains adequate oxygen levels and good quality water. By running livewell pumps constantly and ensuring adequate replacement of water, you will maintain an environment conducive to the fish’s survival. By not doing this, especially in water temperatures that are greater than 75 degrees, you will severely limit the ability of that fish to survive after release.
  5. Fifth, employ proper weigh-in procedures. These are covered in detail within the instructions located at this link.
  6. Sixth, be realistic in assessing the survivability of a fish before release. If the fish does not swim upright, if it appears "bleached" and has little control of its movement or if its scales are is visibly and significantly damaged, then do not release the fish. This is a fish that will likely die and to release it is a waste. Bring the fish home and enjoy a fresh fish fry.
  7. Finally, release the healthy fish into good quality water in the main body of water. This is water which is cool, well oxygenated, and provides immediate access to deep water. Releasing fish (any species) into shallow warm water will have the potential to eliminate all of the positive efforts up to the release. Typically shallow water is hotter and less well oxygenated than the main body of the lake, and the fish which are being released are stressed and require the best release conditions possible for the highest rate of successful release. During organized tournaments (such as bass tournaments) this can be accomplished by using tournament boats to carry the fish to the main body of the lake.


It is not a bad thing to bring fish home for food. Food is perhaps the single biggest reason that many anglers fish (saltwater and freshwater). Yet, if you are going to practice catch & release then you owe it to the fishery to do so in a conscientious and appropriate manner. If you fail to practice proper catch & release techniques, then you are falling far short of achieving the goals of catch & release. And, your failures may often result in numbers of fish drifting ashore days after your trip or after a tournament once they have begun to decompose and subsequently float back to the surface. Not only is this a travesty to have occur and a complete waste of a resource, but it will eventually generate negative public reaction to the practice of catch & release fishing.  It is our responsibility to demonstrate that we as anglers can implement those techniques and follow those processes that make for successful catch & release.

Finally, speak up and educate others on proper catch & release techniques. Take this article with you and copy and distribute it to anyone you know who fishes. Without the knowledge, they may not realize the results of the actions. Through adequate knowledge and the appropriate attitude catch & release can be an enormous benefit to a healthy fishery.

Catch & Release Mortality Studies

This list will grow over time as new studies are posted.

Editor's Note: A special thanks to Gene Gilliland at Oklahoma Fishery Research Laboratory, Dave Willis at South Dakota Department of Wildlife and Fisheries, and Scott Decker at New Hampshire Fish and Game Department for providing information and support for this article as well as the attached studies.

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