<P> In 2011, the National Park Service in Yellowstone National Park began reversing decades of regulation that promoted catch and release and other techniques that protected fish populations . In the name of native fish conservation, they began mandatory kill regulations on rainbow and brook trout in the Lamar River drainage and encouraged unlimited taking and disposal of non-native species, including brown trout in some park waters . </P> <P> 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 (e.g. See research by Steven J. Cooke). That work led to the development of the UN FAO Technical Guidelines for Recreational Fisheries (1). 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 . </P> <P> 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 . </P> <P> 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 . </P>

How many fish die from catch and release