La prima parte del documento riporta alcune linee guida per una corretta pratica del C&R, tradotta da me, mentre nella seconda parte è riportato lo studio completo in lingua inglese (è disponibile una traduzione direttamente nel blog tramite traduttore di Google).
Buon Divertimento.
Catch-and-Release Linee Guida
La maggior parte degli studi sul C&R fino ad oggi erano incentrati sull'analisi dei fattori che influenzano la mortalità dei pesci. Tuttavia, grazie al gran numero di studi che sono stati eseguiti fino ad oggi, stanno emergendo una serie di comportamenti generali da seguire. Così, mentre deve essere usata cautela quando si applicano risultatidi specifiche specie ad altre specie, le seguenti raccomandazioni sono, date le conoscenze di base,sono le linee guida generali da utilizzare per ridurre la mortalità nel catch-and-release per la maggior parte delle specie.
Tecniche di pesca
• Gli ami circle dovrebbero essere utilizzati in quanto riducono al minimo la possibilità di aggancio in profondità.
•Gli ami senza ardiglione sono raccomandati poichè sono più facili da rimuovere e quindi riducono i tempi di cattura.
• L'uso di esche vive/organiche dovrebbe essere scoraggiato in quanto aumenta la probabilità di allamare in profondità.
• L'uso di esche artificiali dovrebbe essere incoraggiato.
• Le lenze non devono essere lasciate incustodite poichè hanno una maggiore probabilità di agganciare in profondità un pesce.
• Lo spessore del filo utilizzato deve essere adeguato alla specie di pesce che stiamo pescando . Questo consentirà di evitare la rottura dello stesso e di ridurre il tempo di combattimento.
• Cercare di evitare di pescare quando la temperatura dell'acqua è troppo calda o fredda se si ha intenzione di rilasciare il pescato.
Salpaggio del pesce
• Il pesce allamato deve essere recuperato al più presto per evitare di stancarlo troppo.
• I pesci devono essere slamati possibilmente a mano bagnata.
• Quando è necessario un guadino, deve essere senza nodi e preferibilmente in gomma morbida.
• Quando salpiamo pesci estremamente grandi (ad esempio muskellunge), l'uso del materassino dovrebbe essere considerato.
Maneggiare e fotografare un pesce
• Tenere i pesci in acqua il più possibile per ridurre al minimo l'esposizione all'aria.
• Non mettere mai le dita attraverso le branchie o negli occhi.
• Non tenere i pesci pesanti dalla mascella in quanto si potrebbe danneggiare la mandibola e le vertebre.
• Tenere pesci di grandi dimensioni orizzontalmente e sostenere il loro corpo per evitare di danneggiare gli organi interni.
• Utilizzare le mani bagnate, guanti o un panno umido per maneggioare il pesce.
• Avere fotocamera pronta prima di salpare il pesce per ridurre al minimo l'esposizione all'aria.
• Se possibile, fotografare il pesce, mentre è in acqua.
Slamare un pesce
• Avere pinze lunghe a disposizione per estrarre l'amo.
• Rimuovere l'amo rapidamente, mantenendo il pesce sott'acqua.
• Se il pesce è allamato in profondità, tagliare la lenza e rilasciare il pesce più rapidamente possibile.
• Evitare l'uso di ami in acciaio inox che impiegano più tempo per sciogliersi se lasciati nel pesce.
Depressurizzazione
• Evitare la pesca in acque profonde (5-6 m) se si ha intenzione di rilasciare il pescato.
• Considerare la profondità di cattura al momento della decisione sul rilascio del pesce.
• Rilasciare il pesce subito dopo che è stato salpato.
• Evitare lo sgonfiamento artificiale della vescica natatoria (spremitura).
Ri-ossigenazione
• Se c'è corrente, tenere il pesce in posizione verticale, rivolto verso la corrente.
• Se non c'è alcuna corrente, spostare delicatamente pesce avanti e indietro in acqua fino a quando i movimenti branchiali tornano alla normalità ed il pesce è in grado di mantenere il suo equilibrio.
• Quando il pesce comincia a lottare, lasciarlo nuotare via.
ORA, PER CHI VOLESSE CIMENTARSI CON LO STUDIO COMPLETO EFFETTUATO DA S. J. Casselman, CHIARAMENTE IN INGLESE, LO TROVERETE QUI DI SEGUITO.
QUESTO DOCUMENTO E' TRATTO DAL SITO http://wildtroutstreams.com
Catch-and-release angling: A
review with guidelines for proper fish handling
practices
S.
J. Casselman
Fisheries Section
Fish and Wildlife Branch
Ontario Ministry of Natural
Resources
July 2005
This report should be cited as follows: Casselman, S. J. 2005. Catch-and-release angling:
a review with guidelines for proper fish handling practices. Fish &
Wildlife Branch. Ontario Ministry of Natural Resources. Peterborough, Ontario.
26 p.
Executive Summary
The
use of catch-and-release practices by anglers is increasing. This increase is a result of both anglers viewing the process as
a conservation technique
and also because
catch-and- release practices are being mandated by fisheries managers. Despite the widespread use of
catch-and-release, there is generally a lack of
understanding regarding
the mortality caused by
the
practice and how variation in catch-and-release techniques may affect
the level of mortality.
Fortunately, the increase in catch-and-release practice
by anglers has coincided with an
increase in research examining catch-and-release practices. While most of
the studies to date have been species
specific, there are general
recommendations that can be made based
on the available information.
While catch-and-release is physiologically stressful, stress and therefore mortality can be
minimized by
following some general catch-and-release guidelines. Gear should be appropriate
for the species being
angled, allowing for quick
retrieval. The use of barbless hooks and circle
hooks should be considered to reduce the amount of time required
to release fish.
Air exposure should be minimized and fish should be released quickly.
Depth of capture, hooking
location and bleeding
should be taken into account
when deciding on whether or not
to release a fish.
When performed correctly, catch-and-release
can be successful with minimal harm to the
fish and should be encouraged. However, due to the variation among species in response
to
catch-and-release techniques,
it is recommended that further
research is needed
to create species- specific guidelines.
Introduction
Over the last several decades
catch-and-release has become a common practice
among anglers. In a review of recreational fishing
in Ontario, which was conducted in 2000, only 5% of anglers surveyed reported that they did not practice
catch-and-release
to some extent (OMNR,
2003). Catch-and-release may be practiced either
voluntarily or because it is mandated.
In Ontario, size limits are used
as a management technique
in many waters for a variety of fish species. Fish may be required
to be released if they are under
a minimum size limit, over a
maximum size limit or within a protected slot size. Additionally, anglers may voluntarily practice catch-and-release as a conservation technique.
One of the key components to the increased use of catch-and-release practices, both by
anglers and fisheries managers,
is the assumption that fish
which are released actually
survive the experience. This assumption comes from the observation that when fish are released after
being caught they generally swim away, apparently unharmed. However,
research indicates that most mortality occurs some time after release (Muoneke and Childress, 1994), thus fish that appear healthy upon release may later exhibit
injuries or distress caused
by catch-and-release practices. Given the potential impact of mortality on the
success of catch-and-release as a management practice, there is an increased demand to understand the level of mortality caused by
catch-and-release and determine how various factors may affect catch-and-release survival.
The
impact of mortality
caused by catch-and-release practices is often underestimated by both
anglers and fishery
managers. From a review of 118 catch-and-release studies
(Appendix
1), which, in total,
involved over 120,000 fish, the average mortality associated with catch-and-
release angling was 16.2%. Thus, while
many anglers may assume that by
practising catch-and- release they are having
no impact on the
fish population, a significant number
of released fish may die. Additionally,
many anglers will continue to fish after they have caught their limit under the
premise that they will release all further fish caught, however they often do
not take into consideration the number of fish which will inadvertently be killed
as a result of this practice.
The
purpose of this review is to synthesize current
knowledge related to catch-and-
release angling and provide some guidelines to minimize mortality caused by catch-and-release practices. While tournament angling is increasing in Ontario, this review does not
examine the special issues related to tournament practices. However, in some instances, findings
from research focused on tournaments are presented, when they can be applied to non-tournament angling situations. Given the special nature
of tournament angling,
and their increase
in popularity, a review
of tournament practices
should be conducted.
Influencing Variables for
Effective Catch-and-Release
Physiological Response
A number of studies have attempted to determine the physiological response to catch-
and-release procedures (e.g. Beggs
et al., 1980; Gustaveson et al., 1991; Tufts et al., 1991; Ferguson and Tufts, 1992; Cooke et al., 2003a). From these studies
a number of general responses can be identified. Extended
play time can result
in exhaustion, this is characterised by
marked acidosis due to the release
of protons into the extra-cellular fluid
from poorly perfused white muscle (Tufts et al., 1991). Specifically
this causes an increase in blood lactate
levels and a decrease in extra-cellular pH (Tufts et al,. 1991).
Once the fish is
landed, air exposure
causes the gill lamellae to collapse,
causing an almost complete loss of gas
transfer. This results in an increase in blood CO2 levels and a decrease
in blood O2 levels (Ferguson and Tufts, 1992). Exhaustive exercise and air exposure have been shown to
produce an increase in cardiac output, with a decrease in stroke volume and an increase in heart rate (Cooke et al., 2003a).
While the
physiological response of fish to catch-and-release practices is relatively well understood, little
is known about the cumulative impact of these sub-lethal stressors.
Some effects
of sub-lethal stress caused by
catch-and-release are reduced
growth, impaired reproductive success and increased
susceptibility to disease
and pathogens. Clapp and
Clark (1989) found that the growth
of smallmouth bass was related to the number of hooking events, such that hooking reduced
subsequent growth. Mason and
Hunt (1967) examined the survival and growth of deeply hooked
rainbow trout over a four month period.
They found that, of the fish that survived to the end of the
experiment, there was no significant decrease in the growth of fish that were released, even for fish in
which hooks were left embedded.
In examining the effects of catch-and-release on reproductive success, Booth et al. (1994)
found that there was no significant difference in the egg survival
of angled and non-angled Atlantic salmon. Conversely, Cooke et al. (2000)
found that in largemouth bass,
which provide parental
care to eggs, fish that were angled incurred increased
brood predation and increased likelihood of brood abandonment. Similarly, smallmouth bass have been found
to have reduced ability to defend
their broods after being angled from their nest (Suski et
al., 2003). Thus, for some
species at least, evidence exists that catch-and-release may result in reduced growth and reproductive success.
In addition to sub-lethal physiological stress, catch-and-release practices could cause injury, which, although initially
does not cause mortality, may have detrimental effects.
For example, hooks may physically damage gills,
jaw, esophagus and eyes.
These injuries may
inhibit locomotion, feeding
or reproduction, all of
which may effectively remove previously healthy fish from the population.
Hook Type
Although considerable variation exists
between species in the effects
of gear type on catch-and-release mortality, several generalizations can be made. While there is some variation
among species, the use of circle hooks tends to reduce
mortality. Circle hooks
differ from traditional J-style hooks in
that the point of the hook
is generally perpendicular to the shank (Figure 1). Circle hooks have been found to be less susceptible to becoming deeply
embedded; however, there is some evidence that, in bluegill, the incidence of eye injuries may be greater
(Cooke et al., 2003b). In a review of the
effectiveness of circle hooks, Cooke and Suski (2004) found that, the use
of circle hooks reduced overall mortality rates by
approximately 50%, but that there was variation among species.
Figure 1. Schematic of two circle hook designs (a,b) and a conventional J-style hook (c) (from Cooke and Suski, 2004).
Barbless hooks are often recommended as an alternative to barbed hooks to
decrease catch-and-release mortality. In fact,
Manitoba and Alberta have regulated that only barbless hooks may used for angling in those jurisdictions to reduce catch-and-release mortality. Barbless hooks have been demonstrated
to reduce handling
time through ease of removing the hook,
thereby decreasing associated mortality (Cooke
et al., 2001). Schaeffer and Hoffman (2002) also demonstrated that the unhooking times of barbless hooks were significantly shorter
than barbed hooks, however, the same study
indicated that anglers
landed 22% more fish using
barbed hooks than barbless
hooks. Similarly, the use of barbless hooks has been found to
significantly reduce mortality in trout (Taylor
and White, 1992). It has
also been suggested that barbless
hooks
reduce tissue damage. Thus, while barbless hooks are generally less harmful
to fish, anglers may
be reluctant to use
them because they perceive that catch rates will suffer.
Live vs Artificial Baits
The
influence of bait type on catch-and-release mortality has also been examined in some
detail. Hooking mortality
has been found to
be significantly greater
with natural baits
than artificial bait in striped bass (Wilde et al., 2000).
Similarly, worm-baited hooks have been
shown to be ingested
deeper than artificial lures and flies in bluegill, resulting in increased
mortality (Siewert and Cave, 1990). In a comparison of hooking mortality of
walleye caught on live
and artificial leeches, mortality was 10% and 0% respectively, the use of
leeches also resulted in deeper hooking
(Payer et al., 1989). Results from smallmouth bass
also show 11% mortality when using minnows and 0% when using spinner lures (Clapp
and Clark, 1989).
Recently the use of scented artificial bait has increased. It is thought
that scented artificial baits may be attacked
by the fish in a similar manner as
live bait, thus increasing
mortality. In support of this hypothesis, Schisler and Bergersen (1996) found that hooking
mortality was significantly higher when
fish were caught on scented bait than when non-scented artificial bait was
used. However, Dunmall et al. (2001)
found that there was no effect of scented artificial bait on catch-and-release mortality of smallmouth bass.
These studies suggest that the use of organic bait, and possibly
scented artificial bait, results
in deeper hooking
which increases the chance
of injury during hook removal and increases the length of time that the fish
are
exposed to air during hook removal. Thus, catch-and-release mortality can be reduced
through the use of artificial bait.
Hooking Location
The
location of hooking has been
shown to affect catch-and-release mortality. Catch- and-release mortality of white seabass was directly related to hooking location,
and all mortalities involved
hook damage to the visceral
region (Aalbers et al., 2004).
Similar results have been found for largemouth bass in which 56% of fish hooked in the esophagus died, while the mortality
of fish hooked in other areas was not significantly different than fish that
were not hooked at all (Pelzman, 1978).
Dextrase and Ball (1991)
found that hooking mortality of lake
trout was largely restricted to those fish that were deeply hooked.
Mortality in northern
pike was also greater
in fish that were deeply hooked
(Dubois et al., 1994). Schisler and Bergersen (1996) reported that mortality
of rainbow trout was significantly greater for fish hooked in the gill
arches or esophagus
than superficially hooked
fish, and this increased mortality was attributed to bleeding intensity associated with hooking location.
These studies all point to the fact that fish which are deeply hooked
suffer increased mortality.
While the increased mortality associated with deep hooking
is understood, it is less clear as to whether it is better to cut the line of deeply
hooked fish or try
to remove the hook, potentially risking further injury
and increased air exposure to the fish.
Aalbers et al. (2004)
examined the growth and survival
of white seabass up to 90
days after catch and found
that survival of fish released with hooks
left in place was enhanced, as compared to fish
with hooks removed, but that growth
was reduced. When hooks were removed
mortality was 65%, compared to 41% when hooks were left embedded. Of the fish in
this study that were released with the hooks left in place, 39% had
successfully shed the
hooks by the end of the
study, however, of the hooks that remained in place there was minimal degradation. These results are similar to those found by Mason and Hunt (1967), who examined the effect of hook removal on the survival
of rainbow trout up to four
months after release. Two-thirds of the fish released
without hook removal survived, while
only 11.5% of the fish which had hooks removed
survived. Additionally, of the
fish that survived with hooks left in place, more than half had shed
the hooks by the end of the
study. Schill (1996) found
that cutting the line on
deeply hooked rainbow trout reduced
mortality from 58%
to 36%, and 60%-74% of fish that were released
with hooks left in place
had managed to discard the hooks
by the end of the study. It has recently
been suggested that for species such as bass and walleye, it may be possible to reduce mortality
caused by deep hooking by removing the hook
through the gills (Strange, 20034). However, to date there have not been any empirical studies
which have demonstrated the effectiveness of this
technique. Thus, despite the relative few
studies which have examined the effect of deep
hooking on mortality, it appears
as though, for some species, mortality
can be reduced if deeply hooked fish are released with the hook left in place.
Bleeding
Myers and Poarch (2000), found that the occurrence of bleeding in hooked largemouth
bass was related to both mortality and hooking location. Of 19 bleeding fish, 47% died, whereas
only 20% of non-bleeding fish died. Bleeding was observed in 48% of fish hooked in the throat
and
50% of fish hooked in the gills, whereas
only 1% of fish hooked in the mouth bled. Similarly, results from Arctic
grayling show that bleeding intensity
was related to hooking
location, however, in this study there
was no relationship between mortality
and bleeding intensity (Clark, 1991). Schisler and Bergensen (1996) found that mortality in rainbow trout was
significantly related to bleeding
intensity. Their model predicted that the probability of mortality
increased from 16% with no bleeding to 40% with heavy bleeding. Mortality has also been
found to be significantly related
to bleeding in cutthroat trout. Mortality was 6.5% in non-
bleeding fish and 52.8% in
fish that bleed (Pauley
and Thomas, 1993).
These studies all show that
the chance of mortality increases if fish
are bleeding, thus, anglers should
consider keeping fish that bleed profusely.
Depth of Capture
When fish are caught and retrieved quickly
from deep water,
injury may result from depressurization. Depressurization can result in over-inflation of the
gas bladder, inability to submerge when released, gas embolisms, internal and/or external haemorrhaging and death.
Freshwater fish have one of two basic types of swim bladders. Fish, such as carp, esocids,
trout and salmon have a duct which connects the swim bladder
to the alimentary canal. These fish can expel gas and make buoyancy adjustments more quickly
than fish such as, bass,
walleye, perch and most panfish
which lack a connecting duct and rely on
diffusion to deflate their swim bladder. Thus, while
susceptibility to depressurization varies among fish species,
it has the potential
to be a significant source of mortality
(Kerr, 2001).
Figure 2. Apparatus used for
deep release of lake trout (photo
courtesy of D. Reid, Ministry of Natural Resources, Owen
Sound)
To
release fish that suffer from depressurization a technique known as “fizzing” has
been developed to artificially deflate swim bladders
by puncturing the swim bladder with a sharp instrument. In a review
of “fizzing”, Kerr (2001) suggested that the practice should be
discouraged, as significant damage can result from the procedure, and that fishing
deep waters
(5-6 m) should be restricted if fish
are intended to be released.
Kerr (2001) also reviewed several
alternatives to “fizzing” for releasing fish caught from deep water. These involved lowering
fish back to the depth they were caught
at for release, by means of a retrievable weight
or
submersible cage (Figure 2).
While little investigation has gone into determining the effectiveness of these alternatives, they are recommended over fizzing. To prevent potential decompression, catch-and-release angling
for species in deep water
should be avoided.
Temperature
Evidence suggests that catch-and-release
mortality is directly related to water temperature, with mortality
increasing at extreme temperatures. In a seasonal comparison of hooking mortality
of bluegill, Muoneke
(1992b) found that mortality
was greater in the summer
when water temperatures were highest. However, this study did not account for other variables, such as differences
in feeding rate or
reproductive status, which may have increased mortality during the summer. Similarly,
mortality in cutthroat trout has been
shown to increase from 0
to
8.6% as water temperature
increased from 8°C to 16°C (Dotson,
1982). In a meta-analysis of black
bass mortality associated with tournaments, a strong relationship was found between water temperature and both pre-release and post-release mortality (Wilde, 1998).
Research from walleye tournaments indicates
that mortality increases with water temperature
and suggests that tournaments should be limited to the spring
and fall (O’Neil and Pattenden, 1992), or when water temperatures
are cooler than 15.6°C (60°F) (Boland, 1994). Wilkie et al. (1997) examined the
post-exercise physiology of Atlantic salmon at 12°, 18° and 23°C, and found that physiological recovery was slowest at 12°C, however,
there was significant mortality
at 23°C. This result suggests that warmer temperatures facilitate recovery but that extremely high temperature increases mortality.
Nuhfer and Alexander (1992)
found that mortality increased with water temperature in brook trout that were bleeding from the gills or throat area as
a result of hooking. Mortality
has also been found
to increase with water temperature in smallmouth
bass (Cooke and Hogle,
2000), largemouth bass (Gustaveson et al., 1991; Meals and Miranda,
1994) and striped bass (Nelson, 1998). Interestingly,
Bettoli and Osborne (1998) found that catch-and-release mortality in striped bass was
linearly related to air temperature but not water
temperature, suggesting the temperature during air exposure
may be more important in determining survival than actual
water temperature. These studies
demonstrate that catch-and-release mortality increases with temperature and special care should be taken with fishing
during extremely warm weather.
There has been a similar concern
with releasing fish that have been angled during ice-
fishing and exposed to cold temperatures. It has been suggested that eyes and gills can be
damaged from freezing on extremely cold days. However, studies examining catch-and-release survival of walleye during ice-fishing found
no evidence of damage or
mortality caused by exposure to cold temperatures (Ellis,
2000). Thus, while brief exposure of fish to cold temperatures may not cause mortality or damage, it is best minimize the time that fish are
kept out of the water
when ice-fishing.
Type of Landing Net
Despite the widespread use of landing nets by anglers there
has been relatively little investigation into the damage caused by
their use or which of the available types
of net result in the
lowest injury to fish. Generally,
it is recommended that the use of landing nets be limited as it
is thought to increase fin damage, and remove the protective mucus layer,
thus increasing susceptibility to disease. Barthel
et al. (2003) examined the effects of landing net mesh type on injury
and mortality in bluegill. They quantified the effects
of netting for a 168
h period after capture and found
that there was zero mortality
in fish that were landed without
a net while fish that were landed with a net experienced a mortality
rate of 4 to 14%.
There was also increased pectoral and caudal fin abrasion and dermal disturbance
(scale and mucus loss).
Of the four types of landing net mesh types compared (rubber, knotless
nylon, fine knotted
nylon and coarse knotted nylon), the knotted
mesh types resulted in greater injury
and mortality than rubber or
knotless mesh. Thus, injury (and therefore mortality) can be reduced if the use
of landing nets is limited to those instances where their use is required to safely land and control fish to
prevent mechanical injury.
However, when the use of a landing
net is required or preferred, it is best to
use one made of rubber or knotless mesh.
Figure 3. Muskellunge being
handled using a cradle (photo courtesy of S. Kerr, Ministry of Natural Resources, Peterborough)
To
assist in handling
large fish (e.g. muskellunge), the use
of cradles is often suggested to minimize stress to the fish. Cradles generally consist
of mesh strung between two
poles to fit the
body shape of the fish (Figure 3).
The use of cradles enables fish to
be restrained in the water while allowing for the removal
of hooks, additionally, a tape measure can be incorporated into the construction of the cradle allowing
for the fish to be measured while
remaining in the water.
Although there have been no scientific studies
examining the benefit of using
cradles for large fish, their use is generally accepted
to be beneficial (Smith, 2001).
Air
Exposure
Ferguson and Tufts (1992) found
that there were direct effects
of air exposure duration
on mortality of rainbow trout.
Rainbow trout that were chased for approximately 10 min had a
survival rate of 88%, however this fell to 62%
for fish that were subsequently exposed to air for
30 s and survival was only
28% for fish exposed to air for
60 s (Ferguson and Tufts, 1992). Cooke et al. (2001) examined the effect
of handling time on
injury and cardiac disturbance of rock
bass. While air exposure did not result in any mortality, bradycardia (decreased heart rate) was
observed during air exposure and cardiac
output increased after fish were
returned to the water. Simulated angling (fish were chased for
30 s) resulted in increased
cardiac output and arrhythmia (irregular heartbeat). Fish that had 30 s of air exposure required
2 h for full cardiac recovery while fish
that were exposed to air for
180 s required 4 h to fully recover (Cooke et al.,
2001). These studies
demonstrate the detrimental effects of air
exposure, and highlight the need
to reduce handling time and air exposure
during catch-and-release.
Recovery Time
In addition to the immediate effect
of catch-and-release, fish may not physiologically recover for some time after being released. Beggs et al. (1980) found that angled muskellunge required 12 to 18 h to recover
from acidosis caused by
angling. Similar recovery periods
have been observed for wild
Atlantic salmon, which after being exercised for approximately 10 min,
were found to have extracellular acidosis
which lasted for about
4 h and blood lactate
levels which remained significantly elevated
for at least 8 h (Tufts et al., 1991).
In a comparison
of hatchery and wild rainbow trout,
Wydoski et al. (1976)
found that hooking induced
increased chloride levels in the blood
and plasma osmolarity changes
which recovered within
8 h (Wydoski
et al., 1976). Cooke et al. (2003a)
examined the cardiac response
of largemouth bass to simulated angling events
and found that approximately 135
minutes were required for cardiac variables to return to pre-exercise levels. The length of
time
required for fish to recover from catch-and-release
practices may help explain why mortality is often delayed until after release.
Size of
Fish
Fish size is thought to be related
to catch-and-release mortality because
larger fish are more difficult to handle, thus higher mortality may be expected
with increased fish size. In support of this hypothesis Meals and Miranda (1994)
found that mortality of tournament-caught largemouth bass was significantly greater
(29% vs 9%) in fish greater than 18 inches
in length when compared to fish that were between 12 and
14 inches in length.
Similarly, in a meta-
analysis of mortality associated with black bass tournaments, Wilde (1998)
found a non- significant, but positive relationship between fish size and initial mortality. However, the increased mortality observed in larger fish in these studies
may be attributed to crowding and
increased oxygen consumption while fish
are stored in live wells and not to an intrinsic
relationship between fish size
and mortality. There are also a several studies
which have examined the relationship between
fish mortality and size and have not found any significant
relationship (Titus and Vanicek, 1988; Schill,
1996). It is important to note that the studies discussed here have examined mortality
and fish size within species and not between species.
Intraspecific studies
are difficult to interpret because
any observed relationship between fish size and mortality may be attributed to other factors which differ between
species, such as feeding behaviour and mouth morphology. However, it may be reasonable to expect that large species, such as muskellunge and pike, may be more susceptible to mortality than smaller species. These large fish are often played
for longer periods
of time and handled longer for photographs, this results in a larger physiological disturbance after angling.
Thus special care should be taken when handling large fish to minimize injury and mortality.
Catch-and-Release Guidelines
Most catch-and-release research to date has
focused on examining species-specific responses to potential
factors which affect
mortality. However, due to the large number
of studies that have been completed to date, a number of general trends are emerging.
Thus, while caution should be used
when
applying species-specific findings
to other species,
the following recommendations
are, given the available knowledge base,
general guidelines to be used to reduce catch-and-release mortality for most species.
Angling Techniques
• Circle hooks should
be used as they will minimize the chance of
deep hooking.
• Barbless hooks
are recommended as they are easier to remove and therefore reduce
handling time.
• The use of live/organic bait should
be discouraged as it increases the likelihood of deep- hooking.
• The use of artificial lures should be encouraged.
• Fishing lines
must not be left unattended as unattended lines
have a greater chance of deeply hooking a fish.
• Fishing line used
should be appropriate to the species
of fish being sought. This will
prevent line breaking and reduce playing time.
• Avoid angling during
extreme water temperatures, both hot and cold, if you
plan on releasing your catch.
Landing a Fish
• Angled fish should be retrieved as quickly as possible to prevent
fish exhaustion.
• Fish
should be landed by hand where possible.
• Where a landing net is required,
it should be knotless
and preferably made of soft rubber.
• When landing
extremely large fish
(e.g. muskellunge), the use of landing cradle should be considered.
Handling and Photographing a
Fish
• Keep fish in
the water as much as
possible to minimize air exposure.
• Never place your
fingers through gills or
in the eyes.
• Don’t
hold heavy fish by the jaw as this
may damage the jaw and vertebrae.
• Hold
large fish horizontally and support
its body to avoid damage to the internal
organs.
• Use
wet hands or wet cloth gloves to handle the fish.
• Have camera ready
prior to landing
fish to minimize
air exposure.
• If
possible, photograph the fish
while in water.
Unhooking a Fish
• Have longnose
pliers available to back the hook
out.
• Remove the hook
quickly, keeping the fish
underwater.
• If
the fish is deeply hooked, cut the line and release
the fish as quickly as possible.
• Avoid
using stainless steel hooks
as they take longer to corrode if left in the fish.
Depressurization
• Avoid
fishing deeper (5-6 m) waters if you intend to release your catch.
• Consider depth
of capture when deciding on whether or not to release
a fish.
• Release the fish
quickly after it is landed.
• Avoid
artificial swim bladder deflation (“fizzing”).
Revival
• If
there is current, hold the fish
upright, facing into the current.
• If there isn’t any current,
gently move fish back and forth in the water
until gill movements return
to normal and it is able to maintain
its balance.
• When the fish
begins to struggle, let it swim away.
Acknowledgements
I thank Steve Kerr who
suggested this project as well as providing assistance and direction in preparation of this report. Cory Suski also provided valuable advice during the preparation of this review. Constructive editorial comments were also provided
by Dr. Bruce Tufts.
Appendix 1: Summary of findings from catch-and-release studies.
Species
|
N
|
Days
|
%
Mortality
|
Reference
|
Blue catfish
|
52
|
3
|
5.1
|
Muoneke, 1993
|
Channel catfish
|
214
|
3
|
19
|
Ott and Storey, 1993
|
Channel catfish
|
704
|
6
|
33
|
Rutledge, 1975
|
Channel catfish
|
14
|
<1
|
0
|
Tilyou and Hoenke, 1992
|
Flathead catfish
|
52
|
3
|
11.5
|
Muoneke, 1993
|
Yellow bullhead
|
20
|
<1
|
0
|
Tilyou and Hoenke, 1992
|
Muskellunge
|
3.5
|
30
|
Beggs et al., 1980
|
|
Northern pike
|
242
|
5-16
|
0-4.8
|
Burkholder, 1992
|
Northern pike
|
94
|
4-10
|
6.4
|
Falk and Gilman, 1975
|
Northern pike
|
185
|
2
|
1-33
|
Dubois et al., 1994
|
Tiger muskellunge
|
217
|
1
|
9.7
|
Newman and Storck, 1986
|
Artic grayling
|
180
|
2
|
0.6
|
Clark, 1991
|
Artic grayling
|
158
|
4-10
|
5.1
|
Falk and Gilman, 1975
|
Atlantic salmon
|
300
|
10-14
|
0.3-5.7
|
Warner, 1976
|
Atlantic salmon
|
149
|
5
|
13
|
Warner, 1978
|
Atlantic salmon
|
177
|
2-5
|
4-35
|
Warner and Johnson, 1978
|
Atlantic salmon
|
1221
|
3-14
|
5.1
|
Warner, 1979
|
Atlantic salmon
|
20
|
0
|
Booth et al., 1994
|
|
Brook trout
|
550
|
7-10
|
1-57
|
Shetter and Allison, 1955
|
Brook trout
|
806
|
1
|
2.6
|
Shetter and Allison, 1958
|
Brook trout
|
630
|
2
|
4.3
|
Nuhfer and Alexander, 1992
|
Brown trout
|
490
|
14
|
13.5
|
Hulbert and Engstrom-Heg,
1980
|
Brown trout
|
107
|
1
|
0.9
|
Shetter and Allison, 1958
|
Brown trout
|
197
|
0-28
|
Shetter and Allison, 1955
|
|
Brown trout
|
215
|
10
|
3-7
|
Barwick, 1985
|
Chinook salmon
|
888
|
4-6
|
22.1
|
Wertheimer et al.,
1989
|
Chinook salmon
|
506
|
5
|
21-25
|
Wertheimer, 1988
|
Chinook salmon
|
100
|
1-5
|
10
|
Bendock and Alexandersdotitir,
1991
|
Species
|
N
|
Days
|
%
Mortality
|
Reference
|
Chinook salmon
|
245
|
5
|
6-11
|
Bendock and Alexandersdotitir,
1991
|
Chinook salmon
|
3618
|
11.8
|
Butler and Loeffel, 1972
|
|
Chinook salmon
|
66
|
2
|
9.1
|
Natural Research Consultants,
1989
|
Coho salmon
|
85
|
35
|
42-55
|
Milne and Ball, 1956
|
Coho salmon
|
147
|
2
|
6.8
|
Natural Research Consultants,
1989
|
Coho salmon
|
4861
|
18.4
|
Butler and Loeffel, 1972
|
|
Coho salmon
|
384
|
69.3
|
Vincent-Lang et al., 1993
|
|
Cutthroat trout
|
652
|
30
|
5.11-5.5
|
Marnell and Hunsaker, 1970
|
Cutthroat trout
|
690
|
30
|
3.8
|
Dotson, 1982
|
Cutthroat trout
|
509
|
10
|
5-73
|
Hunsaker et al., 1970
|
Cutthroat trout
|
72698
|
0.3
|
Schill et al., 1986
|
|
Cutthroat trout
|
578
|
4
|
1.37-48.5
|
Titus and Vanicek,
1988
|
Lake trout
|
129
|
4-10
|
6.98
|
Falk et al., 1974
|
Lake trout
|
67
|
2
|
14.9
|
Loftus et al., 1988
|
Lake trout
|
50
|
2
|
10
|
Dextrase and Ball, 1991
|
Rainbow trout
|
100
|
120
|
95
|
Mason and Hunt, 1967
|
Rainbow trout
|
1000
|
3
|
1-10
|
Klein, 1965
|
Rainbow trout
|
159
|
11-35
|
Shetter and Allison, 1955
|
|
Rainbow trout
|
300
|
120
|
34.5-82
|
Mason and Hunt, 1967
|
Rainbow trout
|
38
|
10
|
5-39
|
Barwick, 1985
|
Rainbow trout
|
574
|
2
|
5.7-36
|
Stringer, 1967
|
Rainbow trout
|
65
|
1-2
|
20
|
Faccin, 1983
|
Rainbow trout
|
346
|
1
|
5.2
|
Shetter and Allison, 1958
|
Rainbow trout
|
900
|
28
|
2.1
|
Jenkins, 2003
|
Rainbow trout
|
281
|
29-34
|
16
|
Schill, 1996
|
Striped bass
|
576
|
3
|
1.87-70.39
|
May, 1990
|
Striped bass
|
307
|
3
|
38.1
|
Hysmith et al., 1992
|
Striped bass
|
113
|
3
|
0-69
|
Childress, 1989a
|
Striped bass
|
464
|
14
|
16-17
|
Harrel, 1988
|
Striped bass
|
215
|
30-40
|
15-29
|
Diodati, 1991
|
Striped bass
|
89
|
>3
|
14-67
|
Bettoli and Osborne, 1998
|
Striped bass
|
153
|
3
|
6.4
|
Nelson, 1998
|
Palmetto bass
|
89
|
3
|
1-29
|
Childress, 1989a
|
White bass
|
122
|
3
|
0.8
|
Childress, 1989a
|
Species
|
N
|
Days
|
%
Mortality
|
Reference
|
Yellow bass
|
5
|
<1
|
60
|
Tilyou and Hoenke, 1992
|
Black sea bass
|
64
|
2
|
4.7
|
Bugley and Shepherd, 1991
|
Crappie
|
15
|
<1
|
0
|
Tilyou and Hoenke, 1992
|
Black crappie
|
202
|
<1
|
19-77
|
Childress, 1989b
|
White crappie
|
226
|
6-11
|
3
|
Hubbard and Miranda, 1991
|
White crappie
|
69
|
18
|
29
|
Childress, 1989b
|
White crappie
|
43
|
3
|
9.3
|
Muoneke, 1992a
|
White crappie
|
13
|
≤504
|
15.4
|
Colvin, 1991
|
Bluegill
|
170
|
3
|
1.1-25.3
|
Muoneke, 1992b
|
Bluegill
|
210
|
3
|
0-18
|
Burdick and Wydoski,
1989
|
Bluegill
|
75
|
10
|
30-88
|
Siewert and Cave, 1990
|
Bluegill
|
200
|
7
|
4-14
|
Barthel et al., 2003
|
Bluegill
|
685
|
3
|
1.3
|
Cooke et al., 2003b
|
Pumpkinseed
|
175
|
3
|
0
|
Cooke et al., 2003b
|
Rock bass
|
80
|
5
|
0
|
Cooke et al., 2001
|
Black bass
|
5
|
Lee, 1989
|
||
Largemouth bass
|
1106
|
1-2
|
3-16
|
Bennett et al., 1989
|
Largemouth bass
|
3283
|
<1
|
14
|
Schramm et al., 1985
|
Largemouth bass
|
3129
|
28
|
32
|
Seidensticker, 1977
|
Largemouth bass
|
261
|
14
|
19.4
|
Archer and Loyacano, 1975
|
Largemouth bass
|
1351
|
6
|
38
|
Rutledge and Pritchard, 1975
|
Largemouth bass
|
1422
|
7-23
|
30
|
May, 1973
|
Largemouth bass
|
1863
|
19
|
14.3
|
Welborn and Barkley, 1974
|
Largemouth bass
|
14-21
|
26.7
|
Schramm et al., 1987
|
|
Largemouth bass
|
285
|
60
|
11.2
|
Pelzman, 1978
|
Largemouth bass
|
2
|
3.2
|
Hartley and Moring, 1991
|
|
Smallmouth bass
|
70
|
7
|
0-11
|
Clapp and Clark, 1989
|
Smallmouth bass
|
634
|
20
|
4.2-47.3
|
Weidlein, 1989
|
Smallmouth bass
|
2
|
8.9
|
Hartley and Moring, 1991
|
|
Smallmouth bass
|
458
|
0-8.5
|
Bennett et al., 1989
|
|
Smallmouth bass
|
61
|
2
|
4.9
|
Jackson and Willis, 1991
|
Smallmouth bass
|
238
|
3
|
0
|
Dunmall et al.,
2001
|
Species
|
N
|
Days
|
%
Mortality
|
Reference
|
Guadalupe bass
|
85
|
3
|
2.4
|
Muoneke, 1991
|
Spotted bass
|
47
|
3
|
8.5
|
Muoneke, 1992a
|
Walleye
|
180
|
12
|
1.1
|
Fletcher, 1987
|
Walleye
|
865
|
5
|
40
|
Goeman, 1991
|
Walleye
|
47
|
3
|
0
|
Parks and Kraai, 1991
|
Walleye
|
2357
|
3
|
21
|
Fielder and Johnson, 1992
|
Walleye
|
14-28
|
5-16
|
Payer et al., 1989
|
|
Walleye
|
240
|
2
|
0.8
|
Schaefer, 1989
|
Walleye
|
123
|
1
|
23
|
Rowe and Esseltine, 2002
|
Sauger
|
74
|
<1
|
4
|
Bettoli et al., 2000
|
Black drum
|
19
|
<1
|
0
|
Martin et al., 1987b
|
Black drum
|
325
|
0
|
Martin et al., 1987a
|
|
Red drum
|
171
|
<1
|
0
|
Martin et al., 1987b
|
Red drum
|
121
|
3
|
4.13
|
Matlock et al., 1993
|
Red drum
|
38
|
3
|
44.7
|
Childress, 1989a
|
Red drum
|
968
|
0.21
|
Martin et al., 1987a
|
|
Spotted seatrout
|
401
|
7
|
37
|
Hegen et al., 1983
|
Spotted seatrout
|
43
|
<1
|
20-70
|
Martin et al., 1987b
|
Spotted seatrout
|
52
|
7-9
|
0-56
|
Matlock and Dailey, 1981
|
Spotted seatrout
|
7
|
17-27
|
Hegen et al., 1987
|
|
Spotted seatrout
|
124
|
3
|
7.29
|
Matlock et al., 1993
|
Spotted seatrout
|
127
|
16.54
|
Martin et al., 1987a
|
|
White seabass
|
221
|
90
|
10
|
Aalbers et al., 2004
|
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