The Consequences of Catch-and-Release Angling: What do we know? by Jim Woollett

Around the globe tens of billions of fish are caught and released annually the likes of sporting, commercial, and subsistence-oriented fishers.

There’s a broad assumption that released fish, especially those that swim away under power, will survive another day. Despite well-crafted intentions, catch-and-release can often result in fish being returned to the water injured. The byproducts of angling (e.g., hooking) and other stressors can compound and cause fish to succumb after release.

Good news, current studies are revealing more effective techniques to aid in fish recovery and fly fishers will find these skills easy to incorporate into their routine. The ability to rapidly assess and recoup a fish after landing will pay dividends now and for generations of fish stocks (and anglers) to come.

While catch-and-release has become widely popular in the U.S., continued practice begs the question: how do we know when fish have been adequately revived? How resilient are fish after release, especially in heavily fished waters?

A biologist usually points to increments of stress as the answer: changes in both physiological and behavioral states in a fish. Developing an understanding means measuring normal versus impaired states in terms of heart rate, respiration, hormones in the bloodstream, feeding intervals, and predator evasion for instance. So far, findings indicate that stress levels vary across families and even species of fish; there is no “one size fits all” criteria.

catch and release peacock bass fishing

The Story of  Nemo (or Mr. Limpet)

When Nemo (metaphor for a healthy fish) is subjected to a short-term aka acute stress, like a microbe attack, he has a biofeedback response that leads to recovery.  In the case of a pesky microorganism, Nemo’s stress level rises and then falls as his immune system overcomes the invader.

Extreme stress such as capture (Nemo is played out on 7x tippet) or compound stress (Nemo is caught, held too long out of water, AND Bruce the Shark is waiting for him after release) may overload a fish entirely.  Now Nemo’s stress level skyrockets and he becomes susceptible to a multitude of internal and external negative effects that can lead to delayed mortality. A fish may die relatively soon (in hours) or later (in weeks) as a result. The release period is the gray area where anglers can help fish the most:  handle fish efficiently after landing and maximize their recovery process to reduce the long-term effects of compound stress.

Consider Angling Best

Practices as a Prizefighter Bout

The first hooking mortality study (by Mr. F. Westerman in 1932) disclosed the surprisingly deadly effects of catch-and-release on angled fish. Since then, nearly 300 catch-and-release mortality studies of over 50 fish taxa, including marine fishes, have been published with some particularly relevant data written in the last five years.

After decades of research, what do we know? Current techniques for minimizing fish injury and stress are often referred to as “best practices” for catch-and-release fishermen. Many best practices you may already know; some will likely be new. Pitched through the lens of a so-called “angler’s prizefighting bout”, here are the high points.



The Weigh-In

(species strategy)

Brawler or mauler? Chances are you’re already acquainted with some of the traits of your finned challenger. Survival of a released fish is improved by knowing (up-front) the competitive class of the species and being prepared.  Whether the tippet-busting headshakes of a taimen or the drag-sizzling runs of a bonefish, use rods and reels that are classed at or above the fighting abilities of the species. Prolonged fighting is one of the top extreme stresses on fish, especially for larger fish that are prone to go the distance with high intensity and to the point of exhaustion.

Use the heaviest tippet possible, especially for contenders that run to structure, inhabit areas with lots of protective cover, or have a toothy grin. A large net or a lip-gripper (for strong, bony-mouthed fish only) will help keep fish in the water when landing. If hooking larger, non-target species is probable, be prepared to tighten the drag and point your rod at the fish to break the line (not the equipment) and stop a lengthy roughhouse before it starts.

For salmonids, when summer water temperatures become too warm (above 19 degrees Celsius/66 degrees Fahrenheit), grab a beverage and go to the neutral corner. Studies show water temperature stress fatalities escalate exponentially above this number; below, they are virtually non-existent.

Know the Fight Before You Step into the Ring

(hooking and landing)

No need for sucker punches; know that hooking-related injuries to fish are the number one cause of angler-related mortalities. De-barbing your flies will also reduce the unhooking time. Avoid additional trauma to deeply hooked fish (i.e., the esophagus) by cutting the line rather than trying to extract a fly. Research demonstrates that barbless flies can be expelled many times faster, both in the mouth and lower in the gut. Whether barbless or barbed, cutting the line and reducing handling will significantly increase the odds of fish survival.

A hooking-related study by Patrick Gargan and others in 2015 showed that Atlantic salmon survival to spawning redds was 55% for lure caught fish and 98% for fly caught fish that were angled. Hook-related injuries can take all forms and often come with a combination punch. For instance, mouth tissue injuries can appear relatively minor, causing a short-term loss of suction during feeding, and have major effects like seasonal weight or growth loss. So be assertive; don’t pull your punch when setting the hook. Artificial flies tend to not only limit tissue damage when set in a timely fashion but are usually planted superficially in the outer jaw.

Anticipate fish runs and use the butt of your rod (incorporate a c-shape bend) to tire burst swimming fish.  Apply side pressure while playing fish in the opposite direction of their movement. Don’t let the fish rest. Pliers and similar instruments that allow swift hook removal with little mouth damage can be especially helpful; keep them handy on your person. Landing nets or fish cradles with knotless, rubberized materials are the way to go to minimize epithelial slime damage. Boat surfaces should be smooth.

Saved by the Bell

(handling environment)

Removing fish from the water is always harmful. When lifted from water, the negative effects of air exposure affect breathing abilities immediately.  In a nutshell, the gill lamellae collapse and gas exchange ceases, the fish starts an oxygen debt cycle, and lactic acid and carbon dioxide levels soar countering recovery. Heart rate slows until the fish is returned to the water where it suddenly spikes like a triple cc injection of intravenous adrenaline.

The longer the period out of water, the longer the cardiac recovery takes. Keep fish in the water while removing the hook. If desired, take up to 5 seconds for a good picture; fish that show water still dripping from their sides are significantly more likely to survive post-photo. Keep the fish in the water between shots. By 10 seconds, most fish are experiencing compound stress levels and delayed mortality can become the champion of this match. Always use clean, wet hands and/or gloves dedicated to handling.

Once the Towel has been Thrown (reflex impairment tests and fish release)

After going rounds, most fish need rehabilitation time. In 2005, Michael Davis published an article on welfare checks that both biologists and anglers can use to scrutinize fish condition and responsiveness. Called reflex (impairment) tests, they are primary indicators of fish health and recovery levels that anyone can perform.  They are based upon fish response to a suite of peripheral stimuli.



Breathing Test:

looking down on the fish, watch for the regular opening/closing of the gills. Ventilation by moving a fish forward and aft or in a figure eight pattern in the water has been largely dismissed in research as having no benefit. Hold the fish stationary. Strong, recurrent gill tempo means the fish is coming around.

Body Flexing Test:

cradle fish underwater by the center of the body and by the tail. Gently flex the body as if swimming. Or you can perform a periodic vertical lift in the water column. A fish will demonstrate an increased muscular response (you’ll feel it in hand) to these movements as it revives.


Equilibrium Test:

lean the fish left or right and test its righting ability. Also check for eye movement as the fish should track and move its eye with the change in position. This test and body flexing (above) can be used simultaneously for fish that have been landed quickly. Fish that do not respond need more time breathing and recuperating blood oxygen levels (per test #1) so let them rest.

Swimming Test:

loosen and tighten a tail hold at the end of the revival process. A tail pump indicates readiness. You may decide to ignore this response if just starting the test series as the fish is still in flight not recovery mode.

In many situations, a recovering fish will have a rest phase that includes taking refuge (e.g., loafing at the bottom of a deep pool or under structure) or even a few feet from the release site in the open water. If nearby, take 5 as your fish revives and let them go through this recovery phase hands free and without interruption.

We’re not on the ropes, catch-and-release fishing has positively impacted both angler catch rates and sustainable fish populations. Angler knowledge of fish recovery practices is a vital component of our future. Rare or protected stocks, like many of the pacific coast salmonids, may be the first to see species-specific best practices for stress recoveries.

- Article Written by Jim Woollett

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