Fishing Techniques - Methods_REVIEW 2018

During an Oklahoma Department of Wildlife Conservation study, up to 43 percent of fish released after being caught died within six days as a result of inadequate holding and weigh in procedures during tournaments.

More recent studies reported in Montana estimate that approximately 20% of released trout die from injuries or stress and even those that don't die, their injuries may significantly reduce their ability to feed and grow

The idea that fish do not feel pain in their mouths has been studied at the University of Edinburgh and the Roslin Institute by injecting bee venom and acetic acid into the lips of rainbow trout; the fish responded by rubbing their lips along the sides and floors of their tanks in an effort to relieve themselves of the sensation.



 Lead researcher Dr. Lynne Sneddon wrote, "Our research demonstrates nociception and suggests that noxious stimulation in the rainbow trout has adverse behavioral and physiological effects. This fulfils the criteria for animal pain." A recent (2014) paper provides a critique of existing studies that purport to demonstrate that fish feel pain.  



James D. Rose of the University of Wyoming argues this may demonstrate a chemical sensitivity rather than pain and that the evidence for pain sensation in fish is ambiguous

Opponents of catch and release point out that fish are highly evolved vertebrates that share many of the same neurological structures that, in humans, are associated with pain perception. They point to studies that show that, neurologically, fish are quite similar to so-called higher vertebrates and that blood chemistry reveals that hormones and blood metabolites associated with stress are quite high in fish struggling against hook and line.
The effects of catch and release vary from species to species. A study of fish caught in shallow water on the Great Barrier Reef showed high survival rates (97%+)   for released fish if handled correctly and particularly if caught on artificial baits such as lures. Fish caught on lures are usually hooked cleanly in the mouth, minimizing injury and aiding release. Other studies have shown somewhat lower survival rates for fish gut-hooked on bait if the line is cut and the fish is released without trying to remove the hook.
Techniques 
Professor with pinched barb

Over the last few decades there has been an emphasis on the development and refinement of science-based practices to increase the likelihood that released fish will survive... See research by Steven J. Cooke). That work led to the development of the UN FAO Technical Guidelines for Recreational Fisheries. 



Effective catch and release fishing techniques avoid excessive fish fighting and handling times, avoid damage to fish skin, scale and slime layers by nets, dry hands and dry surfaces (that leave fish vulnerable to fungal skin infections), and avoid damage to throat ligaments and gills by poor handling techniques. It is also important to use a type of net that is not abrasive to the fish (such as a rubber coated net or lightweight mesh), because fish can easily damage themselves in a hard plastic-style net while thrashing.


Catch and release is a practice within recreational fishing intended as a technique of conservation. After capture, the fish are unhooked andreturned
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The use of barbless hooks is an important aspect of catch and release; barbless hooks reduce injury and handling time, increasing survival. Frequently, fish caught on barbless hooks can be released without being removed from the water, and the hook(s) effortlessly slipped out with a single flick of the pliers or leader. Barbless hooks can be purchased from several major manufacturers or can be 


Created from a standard hook by crushing the barb(s) flat with needle-nosed pliers. Some anglers avoid barbless hooks because of the erroneous belief that too many fish will escape. Concentrating on keeping the line tight at all times while fighting fish, equipping lures that do not have them with split rings, and using recurved point or "Triple Grip" style hooks on lures, will keep catch rates with barbless hooks as high as those achieved with barbed hooks.

Catch and release is a form of Recreational Fishing.

One study looking at brook trout found that barbless hooks did not result in statistically significantly lower mortality rates than barbed hooks when fish were hooked in the mouth, but did elevate mortalities if fish were hooked deeper.  The study also suggested bait fishing does not have a significantly higher mortality when utilized in an active style, rather than a passive manner that allows the fish to swallow the bait. 

To make a hook barbless, the barb is simply crushed flat with a pair of needle-nosed pliers, a trivial task. Medium grit sandpaper can be further used to ensure complete removal of the barb, but this is not necessary and is rarely done.

See also: Pain in fish
Catch & Release angling area on the Stura di Lanzo (Italy).

Catch and release is a conservation practice developed to prevent overharvest of fish stocks in the face of growing human populations, mounting fishing pressure, increasingly effective fishing tackle and techniques, inadequate fishing regulations and enforcement, and habitat degradation. Sports fishers have been practicing catch and release for decades, including with some highly pressured fish species. Proponents of catch and release dispute the suggestion that fish hooked in the mouth feel pain.