The Impact of Recreational Catch and Release

What have we learned and where are we going?

By Dave Votaw

 

 

In 1954, the National Park Service, concerned about native trout stocks in Great Smoky Mountains National Parks, instituted the first catch and release policy in the U.S.  For the next 18 years, most fishermen were completely unaware of the concept of C&R until 1972 when the Bass Anglers Sportsmen’s Society (B.A.S.S.), itself concerned about the sustainability of the required bass populations for tournaments and feeling public pressure from the highly visible stringers of large, dead fish, held the first C&R professional bass tournament on Lake Kissimmee, Florida.  Today, thanks to the efforts of both conservation and fishing industry organizations, the C&R ethic has penetrated to almost all types of recreational fishing – bass to trout to carp and even to sharks.

 

An angler may release a fish for any of a variety of reasons – wrong species, wrong size, ethical concerns – but implicit in the release of a taken fish is the belief that the fish will survive and thus help sustain the fishery.  Current estimates for recreational hooking mortality are an average of approximately 5-10%; a 1998 review of black bass tournament mortality found an average of approximately 25% mortality, although the author stated that the estimate is probably slightly high.  Estimates are just that because most C&R mortality occurs at a significant amount of time post-release, leading to the mistaken belief that C&R mortality is negligible.  We have all thought as a fish is released, “Ok, he’s fine, he swam away.”  However, several physiological, behavioral, and fitness stressors, not necessarily lethal, can be produced by C&R and have long-term impacts on the health of the fish and the overall population.

 

The Cooke Fish Ecology and Conservation Physiology Lab of Carleton University, Canada, has been a leader in research on C&R and tournament fishing implications.  They note that only five species of freshwater fish have been sufficiently studied to allow an understanding of recreational C&R impact:  largemouth bass, walleye, striped bass, Atlantic salmon, and rainbow trout; stripers, salmon, and rainbows are anadromous, of course.  Initial studies of these species have attributed C&R mortality to hooking injuries, water temperature, and cumulative stress.  Additional studies have focused on non-lethal behavioral effects, including changes in activity patterns, swimming speed, movement, and habitat use.  Physiological disturbances produced by C&R are osmoregulatory imbalances, depletion of energy stores, build-up of metabolic wastes, tissue damage, hormonal changes and cardiovascular disturbances.  Finally, sub-lethal fitness effects (i.e., lifetime reproductive success) impact gamete size, quality, and quantity, parental care ability, mating success, and reproductive success.  Thus you can see that the potential impacts of C&R fishing may reach far beyond simple hooking mortality.

 

Based on the research conducted on these five widely divergent species, the Cooke Lab makes the following five general recommendations for conserving recreational fisheries through correct C&R.

 

1.     Angling duration.  The length of time a fish is ‘played’ increases physiological disturbances and recovery time due to depletion of energy stores and accumulation of lactate with other physiological imbalances.  During recovery, the ability of fish to cope with stress, for example from air exposure or predator avoidance, is diminished.

 

The Cooke Lab recommendation:  Anglers should attempt to land fish as rapidly as possible to minimize the duration of exercise and the concomitant physiological disturbance.  Anglers should chose optimal equipment matched to the size of fish that are expected to be encountered.  Efforts to intentionally prolong the angling event through the use of light line or rods should be dissuaded.

 

2.     Air exposure.  During air exposure, gills collapse and the individual filaments adhere to one another, leading to the rapid decline of blood oxygen bound to hemoglobin and anoxia.  Cardiac variables will require significantly more time to return to basal levels; the recovery correlates with duration of air exposure.  Extended air exposure, for example during removal of barbed hooks, measuring and photography, can result in permanent tissue damage and eventually death; 38% of exhausted trout exposed to air for 30 seconds died, compared to 72% mortality following 60 seconds of exposure.

 

Recommendation:  Whenever possible, anglers should attempt to eliminate air exposure by handling fish that are to be released in the water.  When fish must be exposed to air, we urge that anglers do everything possible to minimize the air exposure duration due to the overwhelming negative consequences associated with that action.

 

3.     Water temperature.  Fish taken at high water temperatures, an environmental variable that differs in impact among different species, suffer increased physiological stress, greater oxygen debt, and increased mortality rates.  In addition, the quantity of dissolved oxygen in water decreases with increasing water temperatures.

 

Recommendation:  When water temperatures are their highest, both the duration of the fight and handling time should be minimized.  Ideally, fishing should be restricted during extreme water temperatures.  For Atlantic salmon in eastern Canada, Atlantic salmon rivers are temporarily closed to recreational angling during excessive water temperatures.  Extreme water temperatures are undoubtedly one of the periods where fish are particularly susceptible to mortality.

 

4.     Bait type, terminal tackle, and hooking injury.  An obvious determinant of potential injury and mortality is the use of barbed hooks.  Studies of barbless hooks found that they allow a more efficient release of the fish and produce less tissue damage, thus resulting in less mortality.  In addition, artificial lures and flies tend to hook fish in the mouth, compared with live or organic bait which is more often ingested deeply and thus closer to vital organs, making hook removal more difficult and harmful.

 

Recommendation:  Barbless hooks should be widely adopted by anglers.  Anglers using barbless hooks and reducing the emphasis on the use of organic baits will generally lead to minimal injuries, reduced handling time, and lowered chance of mortality.

 

5.     Angling and the reproductive period.  The benefits of minimizing stress during reproductive activity are obvious – increased offspring to contribute to subsequent year classes.  Studies of largemouth bass found that removal of males from the nest quickly resulted in predation of the unprotected offspring.  Even after returning to the nest, males exhibited impaired swimming behavior for the next 24 hours, and provided less care to surviving offspring.  Studies also suggest that largemouth bass caught immediately prior to the spawning period in a simulated bass tournament format produced fewer and smaller offspring.

 

Recommendation:  Based upon the negative consequences associated with angling during the reproductive period, it is only prudent to avoid capturing fish during the reproductive period.

 

 

Clearly the C&R ethic is deeply embedded in the thinking of conservation-minded fishermen; it is the obvious and easiest tool for sustaining fisheries when done correctly.  It is also clear that, although we are generalizing the guidelines discussed above across a variety of diverse freshwater species, these species of interest vary greatly in their sensitivity to the stress caused by C&R fishing.  Scientists at the Cooke Lab believe that the solution to the C&R dilemma is to “… develop and refine general guidelines for the successful release of all fish, and then develop a suite of specific guidelines for individual species or types of catch-and-release activities (e.g., tournaments, deep water fishes).  Included in these guidelines should be species-specific considerations with respect to different life-stages, populations, sizes or genders.”

 

Further scientific information on this and other fishing conservation topics is available at:  www.carleton.ca/fecpl/C&R_papers.html