There are several good reasons to mandate catch and release. Some species of fish are valued as game fish but aren't good to eat, so it's good for sport fishermen to have some waters where they can catch trophy fish but not keep them. And some species of fish grow slowly enough and are fished hard enough that it is necessary to protect all adults. Also, many fishermen believe it's better to enjoy catching fish and then release them to fight again.

Catch-and-Release Laws

Big-game fish in the ocean are often governed by mandatory catch-and-release laws. These fish are rare enough and less desirable to eat, so catch and release makes sense. In the past, fishermen were allowed to keep one trophy fish to mount; but now that fiberglass reproductions are available, there's no real reason to keep the trophy fish. Marlin, sailfish, and tarpon are good examples of fish that are often mandated catch and release.

Some trout streams are trophy waters where you must release every fish you catch. This ensures that big fish are put back into the water to be caught again. Some bass waters are also catch and release for the same reason. This concept will work on smaller bodies of water but probably can't be effective in bigger lakes and salt water since fish can move to different waters where protection isn't guaranteed.

Catch and release of game fish that grow slowly and have a low reproduction rate also works to allow some fishing for them but protects them, too. Although low creel limits can help, not allowing any fish to be kept is more efficient for some fish. Although some kinds of big-game fish are good to eat, using them for food is not an efficient use of the resource, so catch and release is mandated.

Voluntary Catch and Release

Bass fishermen have long practiced catch and release, and tournaments have encouraged it to the point at which it's a sacrilege to keep a bass in many places. This actually works to harm fish populations in some smaller bodies of water. If bass overpopulate, they can't get enough food, so they won't be healthy and generally won't grow very fast. In larger bodies of water, however, catch and release probably makes no difference to the fish populations.

To be worthwhile, catch and release must be tailored to the specific bodies of water and populations of fish in those waters. Releasing fish after a tournament was started as a publicity tool to combat the image of professional fishermen killing large numbers of fish, and to avoid giving animal rights groups something to use against fishing. For tournaments, it's a good idea to continue to release all fish to avoid any accusations; but the individual fisherman who keeps a few to eat shouldn't be ostracized unless the person keeping the fish is doing so illegally.

In salt water, catch and release has long been a way of life for big-game fishermen, even before it was required. It makes little sense to bring in a tarpon to the dock and kill it just to show it off. Tarpon are not very good to eat so there is no need to keep them. But you can keep many excellent-tasting fish, such as croaker, which also have high creel limits.