The Impact of Recreational Catch and Release
What have we
learned and where are we going?
By Dave Votaw
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.
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.
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.
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.
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.
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.
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.
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
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.
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.
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
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.
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.”
scientific information on this and other fishing conservation topics is