ODNR Division of Wildlife - Fishing - Catch and Release

Catch-and-Release Guidelines

Curtis Wagner and Scott Hale, Fisheries Management, Ohio Division of Wildlife

Catch-and-release fishing has dramatically increased during the past 30 years. This trend has largely resulted from growth in popularity of competitive fishing tournaments, promotion by sportfishing organizations, and an increase in knowledge about the potential benefits of catch-and-release fishing by anglers and natural resource agencies. The ODNR, Division of Wildlife believes that, used appropriately, catch-and-release fishing can be an important fisheries conservation tool. In fact, the Division often relies on regulations that require release of specific sizes or restricts the total numbers of fish that can be kept to improve fishing.

Careful Release Practices are Important

A recent review of over 200 scientific studies indicates that survival of released sportfish averages 82%, yet under certain situations can decrease to nearly 25%! So, as anglers, what can we do to increase the chance for released fish to be caught again? The answer is not as straight-forward as you might think because factors and practices influencing successful catch-and-release fishing are complicated.

Attention to Details Can Improve Success

For catch-and-release fishing to succeed, released fish must not only swim away, but be able to resume normal physiological functions such as swimming, feeding, and growing. Therefore, both initial mortality and delayed mortality must be considered. Initial mortality typically occurs when a fish is hooked in a way that damages sensitive tissues such as the gills or gullet and results in severe bleeding. Even if a fish is not initially wounded, delayed mortality can occur due to the cumulative effects of numerous sub-lethal stressors. Sub-lethal stressors may include:

prolonged exercise by fighting fish for long periods, depleting energy stores and creating lactic acid build-up in muscles;
severe degradation of the protective mucus, or slime coat, by netting the fish with abrasive nets and failing to handle the fish with wet hands, thereby compromising the immune system;
extended air exposure incurred during hook removal, measuring, and taking pictures increasing the time for cardiac processes to return to a normal state; and,
skeletal and muscular compression and extension experienced when fish are held vertically.

The delayed effects of each potential sub-lethal stressor can be worsened by unusually warm or cool water temperatures. In addition, one or more of these primary stressors, and others not listed, can occur at the same time if anglers are not careful with fish they intend to release. The following table synthesizes some general considerations to promote survival of released fish:

Angling Component	Topic	Recommendation	Rationale
Hook and Bait Type	Barbed vs. barbless hooks	Use barbless hooks; crimp/file barbs on conventional hooks	Hooks without barbs can decrease handling time and tissue damage while generally resulting in similar hook-up and landing rates as hooks with barbs.
	Circle vs. conventional "J" hooks	Use circle hooks when fishing with live or cut bait	Circle hooks result in decreased frequencies of deep-hooking and a subsequent decrease in air exposure time due to ease of removal. However, limited evidence suggests decreased capture efficiency in some situations.
	Single vs. treble hooks	Use single hooks; consider replacing treble hooks with single hooks on artificial lures	Treble hooks on artificial lures, especially when in tandem and barbed, increase air exposure time due to increased difficulty of removal.
	Artificial lures vs. natural bait	Use artificial lures when possible and practical	Natural baits are commonly ingested more deeply than artificial lures, resulting in longer hook removal time and consequently greater air exposure.
Playing and Handling Fish	Playing time	Reduce playing time to a minimum by using appropriately rated angling gear for the size of fish targeted	The length of time a fish is played is positively correlated with the amount of physiological disturbance experienced by an angled fish as well as the time required for complete physiological recovery.
	Water temperature	Exercise care if angling during extreme temperatures	High water temperatures is correlated with increased physiological disturbances and increased probability of post-release mortality. Air exposure during extreme cold can cause tissue damage to the gills and eyes.
	Landing nets	When landing a fish with wet hands is not practical, use nets made with knotless nylon or rubber net materials	Coarse, abrasive, and knotted net materials will remove the important slime coat that aides in protecting the fish from outside infections.
	Venting deep caught fish	Do not vent the swim bladder of caught fish	Consensus among studies suggests that venting can actually decrease survival of fish captured from deep water. Further, angling fish from deep water can have adverse physiological effects, decreasing the likelihood of post-release survival, and should generally be avoided.
	Holding a caught fish	Wet hands first and hold the fish horizontally, using a jaw gripping device that can swivel 360° when handling large sport fish	Wet hands minimizes the amount of slime coat removed and a horizontal hold reduces the risk of damage to internal organs and skeletal structures.
	Air exposure	Minimize air exposure by having release tools, fishing gear, and camera organized and readily accessible	The duration of air exposure is positively related to the length of time required for a fish to physiologically recover and to the likelihood of post-release mortality.
Unhooking and Release	Deeply hooked fish	Leave deeply embedded hooks in fish and cut line as close as possible to the hook's eyelet	Removing deeply embedded hooks increases handling time, air exposure, and tissue damage. Most hooks will deteriorate rapidly and pass through the fish.
	Hook removal tools	Have accessible and use hook removal tools including pliers, bolt cutters, hemostats, forceps, etc.	Hook removal tools decrease the time required to remove a hook from the fish, and subsequently decreases the handling time and air exposure.
	Reviving released fish	Hold fish steady and upright or gently move in an 'S' or 'figure 8' pattern; do not move fish in a back-and-forth motion	For a fish to efficiently transfer oxygen from the water to the blood stream, water must pass over the gill surfaces in a front-to-back direction. Moving a fish back-and-forth in the water does not optimize oxygen uptake and can even be detrimental to recovery. Holding a fish steady allow the fish to naturally pulse the gills inducing flow over the gill surfaces.

Click here to download a printable table (PDF).

Catch-and-Release: Special Considerations

The above recommendations are intended to help anglers increase survival of fish that they choose to release. Certain fishing techniques and tactics, as well as species sought, may not always lend themselves to some of these recommendations. Whereas this overview provides a general guide for catch-and-release based on current scientific results, anglers should remember that interpretations of results may vary and that new information can be expected through time. The organization and ideas presented here and in our table were adapted from scientific research summarized in a technical article published in 2007 by Christine Pelletier from Carlton University in Canada.

A Matter of Choice

The Division of Wildlife provides these guidelines to inform anglers of the current scientific understanding of catch-and-release practices. Releasing fish can be personally rewarding and beneficial in certain situations. However, neither catch-and-release fishing nor keeping fish to eat should be considered as ethically superior. Sport fishing has a rich tradition of harvesting fish as table fare, which makes sense given that fish are excellent sources of protein and great to eat! Whatever method of fishing you choose, the Division of Wildlife is working hard to assure that you will have a healthy fishery to enjoy season after season.