Catch and release is a practice within recreational fishing where after capture the fish is unhooked and returned live to the water. Originally adopted in the United Kingdom by coarse fishermen to preserve fish populations, it has since become a widely used technique to permit people to fish recreationally while ensuring sustainability in the face of growing human populations, mounting ecological pressure, increasingly effective fishing tackle and techniques, inadequate fishing regulations and enforcement, and habitat degradation.

Between 18 and 20% of fish released die from injuries and stress, although the rate varies by species. Among those that survive, their injuries may significantly reduce their ability to feed and grow. During tournaments, inadequate holding and weighing procedures may further increase mortality. With deep sea fishing in particular, fish are typically unable to adjust their physiology to the sudden pressure change. Scientific and philosophical debates over whether fish feel pain in a way similar to humans are unresolved. In the 21st century, there is a greater emphasis on developing techniques which increase the likelihood that released fish will survive, such as using barbless hooks. Catch and release is banned in Switzerland and Germany, while Canada requires barbless hooks in some cases.

In the United Kingdom, catch and release has been performed for more than a century by coarse fishermen in order to prevent target species from disappearing in heavily fished waters. Since the latter part of the 20th century, many salmon and sea trout rivers have been converted to complete or partial catch and release. In Scotland, the River Dee operates a full catch and release policy for salmon, grilse and sea trout.

In the United States, catch and release was first introduced as a management tool in the state of Michigan in 1952 as an effort to reduce the cost of stocking hatchery-raised trout. Anglers fishing for fun rather than for food accepted the idea of releasing the fish while fishing in "no-kill" zones. Conservationists have advocated catch and release as a way to ensure sustainability and to avoid overfishing of fish stocks. Lee Wulff, a New York-based fly angler, author and film maker, promoted catch and release as early as 1936 with the phrase "Game fish are too valuable to be caught only once." Don Martinez a West Yellowstone, Montana, fly shop owner, promoted catch and release in his 1930–40s newsletters sent to Eastern anglers.

In Australia, catch and release caught on slowly, with some pioneers practicing it in the 1960s, and the practice slowly became more widespread in the 1970s and 1980s. Catch and release is now widely used to conserve—and indeed is critical in conserving—vulnerable fish species like the large, long lived native freshwater Murray Cod and the prized, slowly growing, heavily fished Australian bass, heavily fished coastal species like Dusky Flathead and prized gamefish like striped marlin.^{[citation needed]}

In Ireland, catch and release has been used as a conservation tool for Atlantic salmon and sea trout fisheries since 2003. A number of fisheries now have mandatory catch and release regulations. Catch and release for coarse fish has been used by sport anglers for as long as these species have been fished for on this island. However catch and release for Atlantic salmon has required a huge turn about in how many anglers viewed the salmon angling resource. To encourage anglers to practice catch and release in all fisheries a number of government led incentives have been implemented.

In Canada, catch and release is mandatory for some species. Canada also requires in some cases the use of barbless hooks to facilitate release and minimize injury.^{[citation needed]}

In Switzerland and Germany, catch and release fishing is considered inhumane and is now banned. In Germany, the Animal Welfare Act states that "no-one may cause an animal pain, suffering or harm without good reason". This leaves no legal basis for catch and release due to its argued inherent lack of "good reason", and thus personal fishing is solely allowed for immediate food consumption. Additionally, it is against the law to release fish back into the water if they are above minimum size requirements and are not a protected species or in closed season.