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Influence of Landing Net Mesh Type on Handling Time and Tissue Damage of Angled Brook Trout

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Influence of Landing Net Mesh Type on Handling Time and Tissue Damage of Angled Brook Trout

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Recreational catch‐and‐release angling is a popular activity. Anglers often use landing nets to shorten fight times, reduce stress on the line and rod, restrict fish movement to facilitate dehooking of the fish, and protect fish from undue harm caused by handling or dropping. Landing nets are constructed using a variety of netting materials that could have varied consequences when coming in contact with fish. Salmonids are among the most targeted fishes in the world, but little is known about how landing nets contribute to postcapture tissue damage. We compared handling time and instances of fin fraying, scale loss, and mucus loss sustained by Brook Trout Salvelinus fontinalis landed by four net mesh types (i.e., large, knotless rubber mesh; knotless nylon micromesh; large, knotted polypropylene mesh; and small, knotless rubber‐coated nylon mesh) or by using bare wet hands in a recreational fishery. The knotted polypropylene mesh resulted in the greatest extent of fin fraying, whereas the bare wet hands method, knotless nylon micromesh, and rubber‐coated nylon mesh resulted in the most scale loss. Interestingly, extended handling times were noted for several mesh types (i.e., knotless nylon micromesh and rubber‐coated nylon mesh) relative to bare wet hands because of hook entanglement in the netting material. However, using bare wet hands to land Brook Trout resulted in higher odds of the fish being dropped into the bottom of the boat. We concluded that the large, knotless rubber mesh was the least damaging to Brook Trout. Changes to angler practices, such as using appropriate landing tools, can benefit fish welfare in catch‐and‐release fisheries.
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Article type : Article
LRH: LIZÉE ET AL.
RRH: INFLUENCE OF LANDING NET MESH TYPE
Influence of Landing Net Mesh Type on Handling Time and Tissue Damage of Angled Brook
Trout
Teah W. Lizée, Robert J. Lennox,* Taylor D. Ward, Jacob W. Brownscombe, and Jacqueline M.
Chapman
Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of
Environmental Science, Carleton University, Ottawa, Ontario, Canada
Andy J. Danylchuk
Department of Environmental Conservation, University of Massachusetts Amherst, Amherst,
Massachusetts, USA
Liane B. Nowell
Kenauk Nature, Inc., Montebello, Quebec, Canada
Steven J. Cooke
Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of
Environmental Science, Carleton University, Ottawa, Ontario, Canada
*Corresponding author: robertlennox9@gmail.com
Received August 8, 2016; accepted October 17, 2017
Abstract
Recreational catch-and-release angling is a popular activity. Anglers often use landing
nets to shorten fight times, reduce stress on the line and rod, restrict fish movement to facilitate
dehooking of the fish, and protect fish from undue harm caused by handling or dropping.
Landing nets are constructed using a variety of netting materials that could have varied
consequences when coming in contact with fish. Salmonids are among the most targeted fishes
in the world, but little is known about how landing nets contribute to postcapture tissue damage.
We compared handling time and instances of fin fraying, scale loss, and mucus loss sustained by
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Brook Trout Salvelinus fontinalis landed by four net mesh types (i.e., large, knotless rubber
mesh; knotless nylon micromesh; large, knotted polypropylene mesh; and small, knotless rubber-
coated nylon mesh) or by using bare wet hands in a recreational fishery. The knotted
polypropylene mesh resulted in the greatest extent of fin fraying, whereas the bare wet hands
method, knotless nylon micromesh, and rubber-coated nylon mesh resulted in the most scale
loss. Interestingly, extended handling times were noted for several mesh types (i.e., knotless
nylon micromesh and rubber-coated nylon mesh) relative to bare wet hands because of hook
entanglement in the netting material. However, using bare wet hands to land Brook Trout
resulted in higher odds of the fish being dropped into the bottom of the boat. We concluded that
the large, knotless rubber mesh was the least damaging to Brook Trout. Changes to angler
practices, such as using appropriate landing tools, can benefit fish welfare in catch-and-release
fisheries.
[INTRODUCTION]
Recreational catch-and-release angling is a popular activity around the globe (Arlinghaus et al.
2007). The premise of catch and release, whether as a voluntary conservation action or as a
mandatory action to comply with management regulations, is that the released fish survive with
negligible tissue damage, stress, or other negative biological consequences (Wydoski 1977;
Cooke and Schramm 2007). It is therefore in the best interest of recreational fisheries managers,
fishing guides, and anglers to adopt practices that are beneficial for fish, including angler
behavior and gear choices (Brownscombe et al. 2017). There is an expanding literature on catch-
and-release science that identifies the practices and gear types that are optimal for a variety of
factors related to the environment (e.g., water temperature, predator burden, and depth) and the
fish (e.g., species, size, and maturation state; Cooke and Suski 2005; Raby et al. 2015;
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Brownscombe et al. 2017).
One aspect of catch and release that has received relatively little study is the landing net
(Arlinghaus et al. 2007). The landing net is a commonly used item of fishing equipment that may
influence tissue damage and postrelease mortality of angled fish. Handheld landing nets are
simple and effective tools that are available to anglers for retrieving fish from the water (Barthel
et al. 2003), reducing the exercise time of a fish, restricting fish movement (Barthel et al. 2003),
holding and manipulating the fish during dehooking (De Lestang et al. 2008), and reducing the
likelihood of harm to the fish from dropping. Landing nets are available with different mesh
sizes, mesh materials, and knot types (e.g., knotless versus knotted); furthermore, some nets are
marketed as species specific (e.g., trout nets), ostensibly because they reduce tissue damage in
comparison with other mesh types. Landing nets constructed of soft knotless nylon, thick rubber,
and knotted polypropylene meshes are widely used in recreational trout fisheries (Barthel et al.
2003). Although landing nets are commonly used in recreational catch-and-release fisheries,
their actual effects on fish are uncertain, likely because fish often show little visual evidence of
harm and may swim away in seemingly good condition (Barthel et al. 2003). The potential for
physical harm to fish from unsuitable net mesh materials includes fin abrasion, fin fraying,
bleeding, mucus loss, and scale loss. Poor net design can also lead to prolonged air exposure and
prolonged handling of the fish. Fin fraying can compromise the fish’s postrelease swimming
ability and can lead to fin rot (Latremouille 2003), whereas scale loss or mucus loss can render
fish more susceptible to infection and disease (Jones 2001; Colotelo et al. 2013; Schwabe et al.
2014). These three metrics (fin fraying, scale loss, and mucus loss) can index the tissue damage
and disturbance experienced by fish upon landing.
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Salmonids constitute an important group of fish in many areas of the world. In Canada,
trout and char are the second most commonly targeted group of species by recreational anglers
(Brownscombe et al. 2014), comprising approximately 20% of annual catches, or about 38.3
million fish per year. The Brook Trout Salvelinus fontinalis is the most popular trout species
captured (DFO 2012). Although trout and char are very well studied in the context of catch and
release (Hühn and Arlinghaus 2011), there is a paucity of data available with which to establish
recommendations on the landing mesh types that anglers should use. The objective of this study
was therefore to assess the effects of various landing mesh types on the tissue damage (including
epithelial injury and fin fraying) and handling time of Brook Trout in a recreational catch-and-
release fishery. Because a wide variety of nets is available to consumers, we selected nets
consisting of varying mesh sizes and materials.
[A]METHODS
[C]Study site.All angling was conducted on Lake Collins (coordinates: 45°44'33.417"N,
74°48'28.5012"E) at Kenauk Nature in Montebello, Quebec, Canada (www.kenauk.com). Lake
Collins is stocked annually with Brook Trout from fish hatcheries near Mont-Tremblant, Quebec.
Lake Collins has a surface area of 0.12 km2, an average depth of 9.14 m, and a maximum depth
of 32 m; no information is available on its bathymetry. It was assumed that the stocked Brook
Trout would respond similarly to wild individuals during capture. Data were collected on four
consecutive days from October 5 to October 8, 2015.
[C]Equipment.The rods, tackle types, and angling methods (casting and trolling) were
implemented in consultation with the Kenauk Nature staff to reflect the practices typical of
anglers in the region. A variety of lightweight spinning rods (light gear strength) was used in
conjunction with a variety of barbed treble hooks equipped with size-2 inline spinners, either
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baited with worms or unbaited. Rods and tackle were rotated between anglers. Kerr et al. (2017)
found that lure and bait type did not significantly influence hooking injury of Brook Trout in
Kenauk. Two small, 3.54-g lead sinkers were attached to braided and monofilament lines
approximately 30 cm above the spinner and did not present an entanglement risk.
Focusing on nets of the correct diameter for trout, we compared four different net mesh
types that varied in dimensions and materials (Figure 1): (1) a large-mesh (25 mm), knotless
rubber net; (2) a micromesh (2 mm), knotless nylon net that was advertised as a trout net; (3) a
large-mesh (40 mm), knotted polypropylene net; and (4) a small-mesh (6 mm), knotless rubber-
coated nylon net. The use of bare wet hands was also included as a treatment because this
technique is often employed by anglers to remove the hook and release the fish immediately and
because it is often assumed to cause less physical damage than netting the fish.
[C]Angling and landing procedures.Brook Trout were angled by five proficient anglers of
similar experience levels, all of whom were given training prior to the study to ensure that
fishing and handling techniques were consistent throughout the experiment. All participants
angled both by actively casting and retrieving the lure from a stationary boat or by trolling the
lures behind the boat while it slowly moved to a new location in the lake. Captured Brook Trout
were landed by using one of the four landing nets or by using bare wet hands. Anglers applied a
treatment for five landings and then rotated treatments in order to balance the number of fish
caught per treatment, until a minimum of 25 fish per treatment group were landed.
Brook Trout were dehooked inside the boat, using pliers when necessary, and then were
placed in a 50-L tank full of lake water; no more than three Brook Trout were held in the tank at
any given time. Angling time, dehooking time, and handling time (all measured in seconds) were
recorded. Angling time started when the Brook Trout was hooked, included the fish being reeled
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to the boat, and ended upon landing of the fish. Dehooking time started when the Brook Trout
was landed, included getting a firm grip on the fish, and ended either when the treble hook was
removed from the fish or when the fish shook the hook. The handling time included the same
parameters as dehooking time but ended when the fish was placed into the tank. The Brook Trout
TL (mm), the hook location, tangling in the net mesh, and the mesh type used were also
recorded. No Brook Trout evaded capture by escaping from the various landing treatments.
To minimize air exposure, Brook Trout were transferred to a tank in which reflex action
mortality predictors (i.e., RAMPs) could be assessed (body flex, operculum closure, mouth
closure, and vestibularocular response; Davis and Ottmar 2006). Visual inspection of the fish
was conducted to confirm the presence or absence of physical damage (i.e., fin fraying, scale
loss, and mucus loss). Only visible, recent damage considered to have been caused by the
landing methods were recorded, and any wounds that were partially healed (e.g., adipose fin
clips or pelvic and pectoral fin damage from hatchery conditions) were not considered damage
from the landing nets. Whether a Brook Trout was dropped or fell to the bottom of the boat was
also noted.
Brook Trout were individually tagged for identification by applying numbered, 18-mm
standard plastic anchor tags (Avery Dennison Ltd., Pasadena, California) in the dorsal
musculature between the pterygiophore bones with a tagging gun. Fish were then transported to
net-pens, either 0.9 × 0.9 × 0.9 m (maximum density = 15 fish) or 1.2 × 1.2 × 1.2 m (maximum
density = 30 fish). The Brook Trout were held in the net-pens for a minimum of 1 h and were
then assessed for mortality and released once the tags were removed.
[C]Analyses.All analyses were conducted using RStudio version 0.98.1091 (RStudio 2014)
<AQ: RStudio 2014 is not found in the references.> running R (R Core Team 2017). Binomial
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logistic regression tests were used to examine the main effects of the various meshes on the
occurrence of scale loss, mucus loss, and fin fraying. For logistic regressions, the bare wet hands
method was selected as an outgroup treatment against which to compare the various net mesh
treatments. Because bare wet hands would have a different set of consequences than net meshes,
assessment of this method can be used to isolate the effect of nets relative to bare wet hands and
allows for a contrast among net types to isolate the effects of mesh type across treatments. Linear
regression was used to analyze the effects of net types on handling time. The average angling
time and dehooking time were also calculated. A ShapiroWilk test (shapiro.test function in
the stats package; R Core Team 2017) was implemented to evaluate the normality of residuals,
and a square-root transformation of the response variable was deemed necessary to satisfy the
assumption of normality of residuals. Owing to nonnormality of residuals, however, we used a
nonparametric KruskalWallis test (kruskal.test function in the stats package) to identify
differences in dehooking time among net treatments, and we used Dunn’s test to conduct post
hoc multiple comparisons (“dunnTest function in the R package FSA; Ogle 2016). Model
outputs were further analyzed using Tukey’s honestly significant difference tests via the glht
function in the multcomp package (Hothorn et al. 2008) to determine any significant
differences among categories, and we assessed variable influence by using odds ratios. For all
analyses, we present means with SEs unless otherwise specified.
[A]RESULTS
Mean surface water temperature at the study site was 13.7°C (SD = 0.8°C), and mean air
temperature was 14.8°C (SD = 2.5°C). In total, 146 Brook Trout were caught and handled for
this study; the fish had a mean length of 310 mm (SD = 34 mm; range = 255468 mm). The TL
of Brook Trout differed among treatment groups (F = 3.04, P = 0.02); however, Tukey’s test
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showed that there was only a significant difference between fish in the rubber-coated nylon and
bare wet hands treatments (t = 3.28, P = 0.01). Angling time was not significantly different
among treatment groups (F = 0.61, P = 0.66); however, dehooking time was significantly
different (F = 6.10, P = 0.00). There was no immediate mortality, and all Brook Trout survived
1 h of holding in net-pens.
The only mesh that was found to cause significant fin fraying was the knotted
polypropylene mesh (z = 2.32, P = 0.02; Table 1), for which the odds of fin fraying increased by
5.20 times compared to the bare wet hands treatment. Otherwise, no significant differences in fin
fraying were detected between fish in the four mesh type treatment groups (Table 1; Figure 2).
The knotless nylon mesh resulted in the highest frequency of scale loss in Brook Trout
(proportion = 0.21; Figure 3), with odds increasing by 1.31 times (z = 0.40, P = 0.70; Table 2)
relative to the bare wet hands method. Brook Trout that were landed with bare wet hands
(proportion = 0.17; Figure 3) and with rubber-coated nylon mesh (proportion = 0.15; Figure 3)
also showed similarly high frequencies of scale loss. The lowest incidence of scale loss was
observed among Brook Trout that were landed with the knotted polypropylene mesh
(proportion = 0.03; Figure 3).
Knotless nylon mesh most frequently caused mucus loss (proportion = 0.32; Figure 4),
increasing the odds by 1.49 times (z = 0.67, P = 0.50; Table 3) compared to the bare wet hands
method. The knotted polypropylene mesh, rubber-coated nylon mesh, and bare wet hands also
yielded similarly high proportions of mucus loss (range = 0.230.30; Figure 4). The large rubber
mesh was associated with the least mucus loss (proportion = 0.07; Figure 4) and decreased the
odds to 0.22 relative to the bare wet hands method.
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The type of net mesh influenced the handling time of Brook Trout in our study. The
longest average handling time (52.6 s) was observed for the knotless nylon mesh; this mesh type
resulted in the greatest frequency of hook tangling in mesh (proportion = 0.68) and, in turn,
longer durations of air exposure. The bare wet hands method had the shortest average handling
time (23.4 s). The large rubber mesh (t = 2.01, P = 0.05; Table 4) and knotless nylon mesh
(t = 4.60, P < 0.01) treatments produced significantly different handing times (Figure 5).
Otherwise, no significant differences were found among the remaining mesh types. The brief
handling time for the bare wet hands method was also probably related to the incidence of Brook
Trout shaking the hook free, which was highest for this treatment (proportion = 0.31)almost
three times the average incidence when landing Brook Trout with any of the treatment meshes
(average proportion = 0.11).
The dehooking time of Brook Trout was significantly different among net types
(χ2 = 16.53, P < 0.01; Figure 6). However, according to Dunn’s post hoc comparisons, the only
significant pairwise difference was between the large rubber mesh and knotted polypropylene
mesh nets (z = 4.05, P < 0.01). The frequency of dropping a Brook Trout was nearly four times
higher for bare wet hands (proportion = 0.24) than when any of the landing nets (average
proportion = 0.05) were used.
[A]DISCUSSION
This study described the physical impacts of landing net mesh types on recreationally captured
salmonids. We found that landing Brook Trout with any of the four mesh types resulted in longer
handling times than the use of bare wet hands, probably because the treble hooks of the lures
frequently became entangled in the mesh of each net type. In a study conducted on the same
system, Kerr et al. (2017) reported that treble hooks did not have a significant effect on mortality
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compared to single hooks but did increase handling time and air exposure because they
encumbered the dehooking of fish. Based on our research, anglers could use rubber-mesh nets to
dehook fish efficiently and reduce the duration of air exposure (Arlinghaus et al. 2007), a
practice that is often recommended as the best option for anglers to land fish (Pelletier et al.
2007; Brownscombe et al. 2017).
Our findings are similar to those of Colotelo and Cooke (2011), who determined that
knotted nylon mesh caused extensive epithelial damage to Northern Pike Esox lucius in
comparison with rubber mesh. However, Colotelo and Cooke (2011) also reported that neither
knotted nylon mesh nor rubber mesh caused noticeable damage to Largemouth Bass Micropterus
salmoides. In a study by Barthel et al. (2003), Bluegills Lepomis macrochirus that were landed
by hand had lower tissue damage rates and mortality than those that were landed by using any
net mesh type. Interspecific differences in scale loss, mucus loss, and fin fraying would likely
arise from differing behavior exhibited by Bluegills, Largemouth Bass, and Brook Trout while
being handled and held out of water. Brook Trout are muscular, are difficult to handle manually,
and can have strenuous avoidance reactions (e.g., confamilial Rainbow Trout Oncorhynchus
mykiss; van Raaij et al. 1996), leading to instances of dropping the fish that might not have
occurred with species that can be handled more securely in air. Barthel et al. (2003) also found
that coarse knotted mesh was overall the most damaging to Bluegills, which is consistent with
our observation that Brook Trout were most heavily damaged by the large, knotted
polypropylene mesh. Barthel et al. (2003) observed that fish landed in knotless mesh, fish landed
in rubber mesh, and control fish (held out of water but not placed in nets) had similarly low rates
of dermal disturbance and that the coarse- and fine-knotted meshes resulted in higher rates of
scale and mucus loss.
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Overall, we found inconsistent patterns of tissue damage among mesh types, highlighting
the challenges and tradeoffs faced by anglers when selecting a landing method. The extent of fin
fraying and the odds of fin fraying were higher when Brook Trout were landed in larger-mesh
nets. When Brook Trout were landed by using nets with large mesh, their fins tended to protrude
from the net, increasing the likelihood of developing damage to connective epithelia, such as
lacerations to the fins. Smaller mesh sizes were more likely to support fins, but they also
increased the odds of scale loss. The large rubber mesh resulted in a much lower incidence of
mucus loss than the other treatments. These conflicting patterns of injury reveal that tissue
damage from landing nets is likely caused by multiple attributes of the net types; thus, further
inquiry into the independent effects of net mesh materials and mesh sizes is warranted.
Proper landing nets can effectively reduce the frequency of tissue damage and
physiological disturbances experienced by Brook Trout in recreational fisheries. Our data
suggest that large rubber meshrather than just rubber-coated meshis the best for mitigating
tissue damage when landing Brook Trout because this mesh type minimized mucus loss and
scale loss and resulted in only moderate fin fraying. Rubber mesh has a firm yet flexible
construction that allows Brook Trout to be supported; the larger mesh size and rubber material
also reduce the occurrence of hook tangling, thereby allowing for relatively short handling times
that minimize air exposure (Arlinghaus et al. 2007; Pelletier et al. 2007; Brownscombe et al.
2017). We discourage the use of bare hands as a landing method because Brook Trout were more
likely to be mishandled and dropped when that treatment was applied.
Many different salmonid species are exposed to capture with fishing nets in commercial,
recreational, and subsistence fisheries. Although assessments of injury and condition in
salmonids that are captured and released as bycatch from commercial or subsistence fisheries
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(i.e., seine nets; e.g., Donaldson et al. 2011; Raby et al. 2015) have provided insight into the
impacts of net injuries, the present study is one of the first to focus on landing nets, which are
used in recreational fisheries and also in other contexts for sorting or transporting fish (see Raby
et al. 2015). Further investigation of rubber-meshed nets of various mesh sizes is recommended
to establish better and more specific recommendations regarding which nets are best suited to
individual fisheries.
[A]ACKNOWLEDGMENTS
This work was funded by the Natural Sciences and Engineering Research Council of Canada
(Engage grant program) in collaboration with the Kenauk Institute. S. J. Cooke was supported by
the Canada Research Chairs Program. We are grateful to Bill Nowell and the Kenauk Nature
staff and to the Quebec Ministry of Natural Resources and Wildlife.
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TABLE 1.Results of logistic regression comparing fin fraying of Brook Trout that were landed
using various net types. Note that the bare wet hands treatment served as the reference level.
Net type
n
Estimate
SE
z-value
Pr(>|z|)
Intercept
27
2.1595
0.6097
3.542
0.000398
Large rubber mesh
30
0.7732
0.7617
1.015
0.310041
Nylon mesh
28
16.4066
1,232.663
0.013
0.989381
Knotted polypropylene
mesh
32
1.6487
0.7107
2.32
0.020358
Rubber-coated nylon
mesh
29
0.3662
0.9549
0.384
0.701312
TABLE 2.Results of logistic regression comparing scale loss of Brook Trout that were landed
using various net types. Note that the bare wet hands treatment served as the reference level.
Net type
n
SE
z-value
Intercept
27
0.4916
3.191
Large rubber mesh
30
0.8817
1.214
Nylon mesh
28
0.6736
0.400
Knotted polypropylene mesh
32
1.1287
1.653
Rubber-coated nylon mesh
29
0.7315
0.247
TABLE 3.Results of logistic regression comparing mucus loss of Brook Trout that were
landed using various net types. Note that the bare wet hands treatment served as the reference
level.
Net type
n
Estimate
SE
z-value
Pr(>|z|)
Intercept
27
1.1451
0.4339
2.639
0.00832
Large rubber mesh
30
1.4939
0.8509
1.756
0.07914
Nylon mesh
28
0.3979
0.5933
0.671
0.50245
Knotted polypropylene
mesh
32
0.1278
0.6092
0.21
0.8338
Rubber-coated nylon mesh
29
0.2801
0.6049
0.463
0.6433
Accepted Article
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TABLE 4.Results of linear regression using the square root of handling times for Brook Trout
that were landed with various net types. Significant P-values are shown in bold italics.
Net type
n
Estimate
SE
t-value
Pr(>|t|)
Intercept
27
4.6147
0.3499
13.189
<2 1016
Large rubber mesh
30
0.9868
0.4907
2.011
0.0462
Nylon mesh
28
2.2979
0.4992
4.603
<0.01
Knotted polypropylene
mesh
32
0.6077
0.4831
1.258
0.2105
Rubber-coated nylon
mesh
29
0.7043
0.5039
1.398
0.1644
FIGURE 1.Close-up images of the four landing net meshes used in this study: large, knotless
rubber mesh (25 mm); knotless nylon micromesh (2 mm); large, knotted polypropylene mesh (40
mm); and small, knotless rubber-coated nylon mesh (6 mm).
FIGURE 2.Proportion (mean ± SE) of Brook Trout that exhibited fin fraying for each net
treatment (see Figure 1) as well as the bare wet hands treatment.
FIGURE 3.Proportion (mean ± SE) of Brook Trout that exhibited scale loss for each net
treatment (see Figure 1) as well as the bare wet hands treatment.
FIGURE 4.Proportion (mean ± SE) of Brook Trout that exhibited mucus loss for each net
treatment (see Figure 1) as well as the bare wet hands treatment.
FIGURE 5.Handling time (mean ± SE) of Brook Trout that were landed by using various net
types (see Figure 1) as well as the bare wet hands treatment.
Accepted Article
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FIGURE 6.Dehooking time (mean ± SE) of Brook Trout that were landed by using various net
types (see Figure 1) as well as the bare wet hands treatment.
Accepted Article
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Accepted Article
This article is protected by copyright. All rights reserved.
Accepted Article
This article is protected by copyright. All rights reserved.
... Net mesh used in fisheries and aquaculture can vary by material, although the most common types are nylon, polypropylene, polyethylene and thick rubber (Lizée et al., 2018). The type of mesh material can modulate the magnitude of netting injuries. ...
... The type of mesh material can modulate the magnitude of netting injuries. Among mesh material, nylon has proved to induce greater damage on fish skin during net retention compared to soft textile net (Gallardo et al., 2010), rubber or polypropylene (Barthel et al., 2003;Lizée et al., 2018). However, most studies on net material are related to fisheries with long netting times, while there is scarce information for aquaculture or shorter procedures. ...
... Colotelo and Cooke (2011) reported that neither knotted nylon mesh nor rubber mesh caused significant injury to largemouth bass, Micropterus salmoides, but caused extensive epithelial damage to northern pike, Esox lucius, after 30 s of netting. Differences on scale loss, mucus loss, and skin integrity induced by netting in different species would likely arise from differing behavior of each species, with more muscular or wild species, having strenuous avoidance reactions (Lizée et al., 2018). Another factor that could explain A. altiparanae sensitivity to netting is the small size and easy detachment of the scales of this species. ...
Article
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Farmed fish are permanently exposed to management procedures such as netting that can result in stress, skin injuries and subsequent secondary infections. The type of mesh material can modulate the magnitude of netting injury, yet there is scarce information on this topic for aquaculture species. The aim of this study was to evaluate the influence of net material on experimental infection by Aeromonas hydrophila using male and female Astyanax altiparanae, yellowtail tetra, as an infection model. Two hundred and fifty six A. altiparanae were distributed into 16 groups considering sex, types of net material (nylon, polypropylene, polyethylene, and a control group handled without net), and immersion challenge with A. hydrophila. Prior to infection, fish were anesthetized and submitted to netting for 30 s. Immediately, a fluorescein bath was applied under UV light to detect skin lesions. Later, fish were infected by immersion challenge in diluted bacterial solution, while control groups were immersed in sterile PBS. It was verified that the fish handled with nylon net mesh showed more extensive lesions than groups handled with polypropylene and polyethylene nets. Survival after infection was significantly lower in fish previously handled with nylon net when compared to all other groups, while no differences were found between polypropylene, polyethylene nets or fish handled by hand. There was no gender influence on lesions or mortality. It was concluded that yellowtail tetra is sensitive to netting and polypropylene and polyethylene capture nets should be used for handling this species. Additionally, nylon hand nets should be banned to avoid injuries that could serve as gateways for opportunist pathogens such as A. hydrophila
... Once reeled in to the boat, improper handling of fish can lead to air exposure (reviewed in Cook et al., 2015), slime loss, or physical injury to internal organs (reviewed in Brownscombe et al., 2017). Other factors related to handling that have been suggested to influence injury rates are the material and mesh size of landing nets (Lizée et al., 2018) and the use of mechanical lip-gripping devices (Danylchuk et al., 2008;Skaggs et al., 2017). More experienced anglers may have greater knowledge of proper handling techniques or of how to use appropriate equipment to minimize stress and injury. ...
... It was hypothesized that lure characteristics (lure type, size, and number of hooks) would influence the dehooking time (Fig. 1a) as well as welfare outcomes (occurrence of blood, hooking depth and location, and reflex impairment; Fig. 1b). Specifically, lures with more hooks were expected to lead to prolonged dehooking time (because of the higher chance for entanglement with the net or line and higher number of hooks to remove; Lizée et al., 2018) and higher occurrence of blood, while larger lures were expected to result in shallower hooking depths because the fish would not be able to ingest it as far . Angler experience was hypothesized to influence the landing time, as well as welfare outcomes in largemouth bass ( Fig. 1), with more experienced anglers having shorter landing times, and fewer instances of injury. ...
... Being hooked multiple times likely resulted in prolonged dehooking times because it was more difficult to remove the hook from the fish ( Bartholomew and Bohnsack, 2005). Crankbaits and other lures with six hooking points may also resulted in prolonged dehooking times because extra hooks not embedded in the fish may have tangled in the landing net or pierced the hand of the person performing the dehooking (similar to what was found by Lizée et al., 2018). In other studies, prolonged air exposure associated with longer dehooking times often resulted in loss of equilibrium, behavioural impairments (e.g. ...
Article
Catch-and-release (C&R) angling is common with anglers releasing a portion of their catch to comply with harvest regulations or because of their conservation ethic. The basis of C&R lies in the assumption that a large proportion of the fish survive and experience limited fitness consequences – that is, the welfare status of individual fish is maintained. However, the level of experience of an angler, as well as use of different gear and lure types, can greatly influence the rate of hooking injury and mortality. These relationships have been documented for a variety of fish species, but few studies have considered the influence of both angler experience and gear or lure type simultaneously. The aim of this study was to evaluate the relationships between angler experience, lure characteristics, landing time, hooking injury, and handling time in the Largemouth Bass (Micropterus salmoides). Largemouth Bass were captured by hook and line between July and September 2018 by anglers with a wide range of experience (novice to professional). During and after these events, measurements were taken on fish characteristics, angler experience, lure characteristics, and welfare outcomes. Generalized linear models indicated that lure characteristics (lure type, size, and number of hooks) had a significant influence on fish injury and handling time, whereas angler experience did not. Specifically, lures with more hook points resulted in shallower hooking depths but longer dehooking times. These results indicate that lure choice is an important aspect of managing C&R fisheries. When choosing a lure, there may be a tradeoff between minimizing the physiological stress associated with handling and air exposure, and reducing the chances of injury and deep hooking. Additional research is needed to better understand such trade-offs across a range of environmental conditions and species.
... This means identifying species and fishery specific guidelines and best practices for C&R (Brownscombe et al., 2017;Cooke and Suski, 2005), and ensuring that they are adopted and used correctly by recreational anglers, whose knowledge, skills, and motivations can vary greatly between individuals and locations (Arlinghaus et al., 2007;Danylchuk et al., 2018). The biological side of C&R has been the focus of many studies, allowing for the identification of general best practices (Brownscombe et al., 2017), and a range of important fishery specific recommendations (Fobert et al., 2009;Lennox et al., 2015;Lizée et al., 2018). However the decisive role of angler attitudes and perspectives in C&R success appears to have received less attention at a fishery specific level (Cooke et al., 2017a), as fisheries managers and scientists have traditionally been more oriented towards biology and with less focus on these human dimensions of the social-ecological system (Cooke et al., 2017a;Fenichel et al., 2013;Hunt et al., 2013). ...
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The wide variety of perspectives and actions of individual anglers contribute greatly to success or failure when adopting and implementing fisheries management tools. Catch-and-release (C&R) is one such tool where success is influenced by both variation in human factors, but also species and fishery specific characteristics. In this study, an intercept survey of 94 sea trout anglers in a C&R dominated fishery on the Swedish island of Gotland investigated motivations to release or retain catches, self-assessment of anglers' own ability to release fish, and their rating of the importance of various factors influencing the successful outcomes of C&R. Retention of catches was most strongly motivated by situations where anglers deemed the fish unlikely to survive, however more than half of anglers acknowledged being unaware of delayed mortality in released fish. The spawning status of an individual fish was the primary motivation for release, particularly among anglers that prefer to keep at least some of their catches. The roles of water temperature, using single, and barbless hooks were scored as significantly less important than other components contributing to the success of a release. Anglers that gave a favourable rating to their ability to release sea trout also gave greater importance to various factors influencing the success of release, reported higher catch per unit effort, and released a greater proportion of their catches. These findings are discussed in the context of bridging knowledge and behavioural gaps around best practices for C&R in this fishery.
... Walbaum 1792) angling(Twardek et al., 2018). This net choice for landing S. trutta can allow for less air exposure, reduced handling stress for the fish, lower levels of elevated glucose, less fin fraying, scale and mucus loss, as well as the net operating as a recovery bag prior to release(Brownscombe et al., 2013;Liu et al., 2014;Lizée et al., 2018;Twardek et al., 2018).The small sample size at higher water temperatures (≥14 C,n = 23) made it difficult to fully investigate the compounding effects of other factors on stress responses of S. trutta caught under such conditions, as air exposure and other influences were limited in an attempt to isolate the impact of water temperature and to reduce the risk of post-release mortality occurring as part of this study. Where post-release mortality of S. salar caught in rivers during their spawning migrations has been measured in relation to water temperature, observations have shown marked increases in mortality in cases ...
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This study investigated the biophysical responses of sea run brown trout Salmo trutta to catch‐and‐release in the coastal fishery around Gotland, Sweden. It used information recorded on individual angled S. trutta (n = 162) including fight time, handling time, total air exposure time, injury, bleeding, fish length, body condition, spawning status, water temperature, hook location and difficulty of hook removal. Reflex action mortality predictors (equilibrium, operculum beats, tail grab response, body flex response, and vestibular‐ocular response), tests of blood glucose and lactate, and observation of hooking injury to measure the relative impact of the angling event on the fish's physical state and stress experienced. The results of this study suggest low rates of post release mortality and generally limited stress responses to angling events, and relatively high post release survival supported by the recapture of many tagged S. trutta. However, a number of scenarios were identified in which stress responses are likely to be compounded, and where anglers should take additional action to reduce sub‐lethal physiological disturbances and the risk of delayed mortality. Particular care should be taken to limit cumulative total air exposure to <10 s, reduce handling time, and risk of additional injury in angling events with extended fight times, when water temperatures >10 °C, or where S. trutta show evidence of being physically compromised by injury or having recently spawned. The results also indicate the importance of using appropriately sized single hooks, rather than larger treble hooks to reduce hooking injury and handling time during unhooking. This article is protected by copyright. All rights reserved.
... extreme flow events and Whirling's Disease) as has been observed in the Findings from our study suggest potential changes that managers can implement as part of a safe operating space approach to fisheries management (Carpenter et al. 2017). Gear restrictions could be implemented for fisheries using dip nets such as decreased mesh sizes (Sangster et al. 2008) and use of materials that may be less injurious to fish such as knotless rubber ( Lizée et al. 2018). As fish caught by beach seine had low injury rates with 5 cm stretch mesh, using a similar mesh size may be an effective gear restriction for fisheries using dip nets. ...
Article
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Steelhead Oncorhynchus mykiss are captured and released during spawning migrations by the commercial, subsistence (Indigenous), and recreational fishing sectors, though the consequences of these fisheries interactions on Steelhead migration are poorly understood. This study evaluated injury, reflex impairment, behaviour, and survival of released wild adult Steelhead following capture in the subsistence dip net, subsistence beach seine, and recreational angling fisheries of the Bulkley River, British Columbia. Wild Steelhead were captured using common handling practices employed in each fishery and were monitored post‐release using radio telemetry. A greater proportion of Steelhead captured by dip net and seine had impaired righting reflexes compared to angled fish, but only fish captured by dip net had notably higher incidence of injury (i.e., net marks, torn fins, flesh wounds, scale loss). Fish captured by dip and seine net had considerably faster peak migration rates (> 4000 m‐day−1) than angled fish (< 1000 m‐day−1) which likely reflects when the Steelhead are encountered during their migration in these fisheries (earlier vs. later stages). Air exposure (15‐74 s) and water temperature (9.2‐15.1 °C) at the time of capture had significant negative relationships with 24‐h fallback behaviour (temperature only), intermediate‐term (10‐20 d after capture) migration rates, and peak migration rates in dip net captured Steelhead. There were no significant effects of capture duration or fish length on injury, righting reflexes, or migratory behaviour. Immediate mortality upon release was rare and occurred in only one fish captured by dip net. The 3‐d survival was 88‐97% for dip net caught Steelhead, 96‐100% for seine caught Steelhead, and 68‐100% for angled Steelhead. Despite inherent differences in timing and location between these fisheries, findings suggest air exposure and water temperature can decrease Steelhead migration rates. Fishers should look for opportunities to avoid or minimize these capture and handling conditions when releasing Steelhead. This article is protected by copyright. All rights reserved.
Article
Fish captured and released by recreational anglers are often exposed to air to enable hook removal and for admiration (e.g., photography). It is necessary to identify thresholds for air exposure that minimize sublethal alterations to inform best practice guidelines yet doing so in ecological-relevant field settings is challenging. We developed a novel attachment method for tri-axial accelerometer and depth biologgers to quantify short-term post-release behaviour in recreationally angled northern pike (Esox lucius), smallmouth bass (Micropterus dolomieu), and walleye (Sander vitreus) following a range of air exposure treatments (i.e., 0, 15, 30, 60, and 180 s). The biologgers were attached to the fish using a quick-release Velcro® harnesses that facilitated easy retrieval of the device from free-swimming fish without the need to recapture the individual. For this study, biologgers were retrieved after a 10 min observational period. Overall dynamic body acceleration (ODBA) was calculated from accelerometric data to estimate post-release swimming activity. Clustering of ODBA via k-means was used to classify distinct movement patterns: resting, steady-state swimming, and high intensity swimming occurrences. In northern pike, ODBA in the first minute after release was significantly higher in the 0 s air exposure treatment compared to the 15 s, 30 s, 60 s, and 180 s treatments, however the same patterns were not observed for smallmouth bass or walleye. We did not observe differences in the time spent resting, time spent steady-state swimming, or the number of high intensity swimming occurrences among air exposure treatments across all study species. This proof-of-concept study demonstrated the utility of this non-invasive bio-logger approach for the short-term study of catch-and-release and also revealed that for the species and context (e.g., water temperatures of 17–25 º C) studied here, air exposure had relatively little negative short-term impact on behaviour or reflex impairment. Nonetheless, we encourage air exposure to be minimized as longer fight times or higher water temperatures may interact with air exposure to increase behaviour impairments and negatively impact survival.
Article
Recreational fishing can result in deep hooking (e.g. in the gullet) of fish that are intended to be released, leading to the development of various tools intended to assist with hook removal. So‐called “hook disgorgers” are typically marketed as being a mechanism to retrieve the hook while doing so in a way that reduces harm to the fish, despite there being many studies that demonstrate that it is best to cut the line for deeply hooked fish. A study was designed to test the effectiveness of six different hook disgorgers for deeply hooked smallmouth bass, Micropterus dolomieu Lacépède, captured using baitholder hooks relative to shallow hooked controls and fish for which the line was cut. Reflex impairment and survival at 10 min, 1 hr and 24 hr were assessed. The study was terminated after early results revealed that all but one of the fish that had the hook removed died (n = 17), while all fish that were hooked in the jaw (n = 4) or had the line cut (n = 5) survived. The ethical conundrum faced by the research team is discussed here, recognising that an incomplete study would have less statistical rigour even though it was very clear that disgorgers used when hooks were in the gullet killed the fish. Stopping rules are common in pharmaceutical trials and can also be used to inform catch‐and‐release research to maintain fish welfare. Best practices for anglers include cutting the line when fish are hooked in the gullet, and changing fishing strategies and gear type when deep hooking is encountered on a routine basis, otherwise mortality can be unnecessarily high.
Article
Best-practice guidelines to improve recreational fishers’ handling during catch-and-release (C&R) events are critical to improve the conservation and management of fish stocks worldwide. While best-practice research is growing, there are knowledge gaps, with the effects of sand exposure on fish mucous membranes understudied. This study aimed to determine the effects of exposing a fish to sand during a C&R event. A total of 360 juvenile (48–137 mm TL) Cape stumpnose Rhabdosargus holubi were subjected to a simulated C&R event during which they were either held: (i) with wet hands, or (ii) dry hands; or with wet hands and then placed on either (iii) wet sterilised sand, (iv) dry sterilised sand, (v) wet unsterilised sand, or (vi) dry unsterilised sand. Fish were maintained in a recirculating system for two weeks, euthanised and subjected to an examination of their mucous layer (bacterial counts, abrasion counts and percentage of abrasion area) and an internal biological assessment. Bacteria from fish mucous layers were cultivated on agar plates to count bacterial colonies. Fish appeared to be healthy and mortality was low (2.5%) after the two-week treatment period. There were no significant differences in the number of skin abrasions among treatments. Although not significant, unsterilised-sand treatments had higher mean bacterial counts and large variation among individuals. Variation was attributed to abrasion and subsequent exposure to foreign bacteria in these treatments. Although the findings suggest that exposure to sand did not negatively affect fish health and survival, larger fish may be more susceptible to abrasions and infections.
Article
Full-text available
Catch-and-release angling is common in recreational fisheries. During handling and dehooking, fish are subjected to stress and dermal injuries, which may result in infections by pathogens after the fish is released. The objective of this study was to evaluate the consequences of common handling practices used by anglers on the postrelease behavior and fate, particularly the susceptibility to disease, of undersized Rainbow Trout Oncorhynchus mykiss. Behavior immediately following capture and subsequent release of fish was examined in a 40-L container, and long-term fate was studied for 2 weeks in tanks incubated withSaprolegnia parasitica zoospores. Trout were behaviorally impaired as indicated by the ease of being netted following the simulated fight associated with catch and release, but there were no further behavioral impacts due to subsequent handling. None of the Rainbow Trout developed fungal infections nor was any significant mortality observed after 2 weeks; only 1 out of 137 fish died. Our data indicate that juvenile hatchery-reared Rainbow Trout have a high resilience to Saprolegniainfection handling-induced stress.
Article
Full-text available
Fisheries and Oceans Canada has collected a unique, long-term data set on the social, biological, and economic dynamics of Canada's recreational fisheries. Starting in 1975, these data were collected through mail surveys to recreational anglers at 5-year intervals. A longitudinal analysis revealed that there was an average of 4.5 million licensed anglers catching an annual average of 255 million fish. Release rates were relatively high (53% of fish released on average), with recent survey data (2010) suggesting that release rates had exceeded 60%. Recreational anglers also contribute an average of $8.8 billion each year to the Canadian economy. However, recreational angling has become less popular over time, and the average age of participants has increased. The data were also useful for characterizing Canada's fisheries, including species-specific catch and harvest. Canada is one of the few countries to collect such extensive recreational fisheries data at a national scale and to do so at regular intervals, an approach that could be modeled by other countries.
Article
The objective of catch-and-release angling is for the fish to survive with minimal fitness consequences. However, fish survival can be compromised by a number of factors, especially anatomical hooking location. To evaluate whether hook type or bait influence hooking outcomes, we tested different combinations of hook (treble or single siwash hooks) and bait (hook tipped with worm or no worm) while angling for brook trout (Salvelinus fontinalis) with inline spinner-style fishing lures. The study was conducted at spring water temperatures (∼20 °C) in small lakes stocked with trout in southwestern Quebec, Canada. Incidences of hooking in the interior of the mouth (i.e. internal hooking) were uncommon (19%), did not differ significantly between hook types or bait treatments, and occurred independently of fish size. Reflex impairments after hook removal were not related to hook or bait treatment. Short-term mortality was quantified with 24 h holding in net pens and was determined to be infrequent for all treatment groups (treble/worm: 6%; treble/no worm: 5%; single/worm: 2%; single/no worm: 0%). Although no fish were hooked in the gills, esophagus, stomach, odds of mortality increased by 14.21 when fish were hooked internally, which is consistent with the position that hook placement is an important predictor of the fate of fish released by anglers. However, our finding that neither hook nor bait type significantly increased the odds of internal hooking, bleeding, reflex impairment, or mortality in this study suggests that restrictions imposed on the use of baited lures or certain hook types attached to lures when fishing may have little influence on short-term catch-and-release mortality of brook trout at these temperatures.
Article
Research on fisheries bycatch and discards frequently involves the assessment of reflex impairment, injury, or blood physiology as means of quantifying vitality and predicting post-release mortality, but exceptionally few studies have used all three metrics concurrently. We conducted an experimental purse seine fishery for Pacific salmon in the Juan de Fuca Strait, with a focus on understanding the relationships between different sublethal indicators and whether mortality could be predicted in coho salmon (Oncorhynchus kisutch) bycatch. We monitored mortality using a ∼24-h net pen experiment (N=118) and acoustic telemetry (N=50), two approaches commonly used to assess bycatch mortality that have rarely been directly compared. Short-term mortality was 21% in the net pen experiment (∼24 h) and estimated at 20% for telemetry-tagged fish (∼48-96 h). Mortality was predicted by injury and reflex impairment, but only in the net pen experiment. Higher reflex impairment was mirrored by perturbations to plasma ions and lactate, supporting the notion that reflex impairment can be used as a proxy for departure from physiological homeostasis. Reflex impairment also significantly correlated with injury scores, while injury scores were significantly correlated with plasma ion concentrations. The higher time-specific mortality rate in the net pen and the fact that reflexes and injury corresponded with mortality in that experiment, but not in the telemetry-tagged fish released into the wild could be explained partly by confinement stress. While holding experiments offer the potential to provide insights into the underlying causes of mortality, chronic confinement stress can complicate the interpretation of patterns and ultimately affect mortality rates. Collectively, these results help refine our understanding of the different sublethal metrics used to assess bycatch and the mechanisms that can lead to mortality.
Article
In lakes and rivers of eastern Ontario (Canada) commercial fishers use hoop nets to target a variety of fishes, but incidentally capture non-target (i.e., bycatch) gamefish species such as northern pike (Esox lucius). Little is known about the consequences of bycatch in inland commercial fisheries, making it difficult to identify regulatory options. Regulations that limit fishing during warmer periods and that require frequent net tending have been proposed as possible strategies to reduce bycatch mortality. Using northern pike as a model, we conducted experiments during two thermal periods (mid-April: 14.45 ± 0.32 °C, and late May: 17.17 ± 0.08 °C) where fish were retained in nets for 2 d and 6 d. A ‘0 d’ control group consisted of northern pike that were angled, immediately sampled and released. We evaluated injury, physiological status and mortality after the prescribed net retention period and for the surviving fish used radio telemetry with manual tracking to monitor delayed post-release mortality. Our experiments revealed that injury levels, in-net mortality, and post-release mortality tended to increase with net set duration and at higher temperatures. Pike exhibited signs of chronic stress and starvation following retention, particularly at higher temperatures. Total mortality rates were negligible for the 2 d holding period at 14 °C, 14% for 6 d holding at 14 °C, 21% for 2 d holding at 17 °C, and 58% for 6 d holding at 17 °C. No mortality was observed in control fish. Collectively, these data reveal that frequent net tending, particularly at warmer temperatures, may be useful for conserving gamefish populations captured as bycatch in inland hoop net fisheries.
Article
Few studies have examined the effects of fisheries capture on wild fish, particularly in the context of evaluating the sustainability of capture and release methods for Pacific salmon (Oncorhynchus spp.) during upriver migration. This study examined the physiological condition, post-release behaviour and survival of adult migrating sockeye salmon (O. nerka) in the Fraser River, British Columbia, Canada. Fish were captured by either beach seine or angling and released immediately, or were captured by angling and released following a 24-h recovery period in a net pen. Before release, all salmon were biopsied or tagged with radio telemetry transmitters. Capture by either angling or beach seine with immediate release resulted in >95% survival 24h after release, whereas net pen recovery after angling resulted in ∼80% survival. This differential in survival was similarly expressed in the percentage of released fish reaching natal sub-watersheds, with 52.2% and 36.3% of fish immediately released by beach seine and angling reaching natal sub-watersheds, respectively, compared with 2.9% of fish released after angling and net pen recovery. Blood plasma stress indices reflected the 10-fold difference in survival, with a ∼4-fold higher plasma cortisol, a ∼2-fold higher plasma glucose and significantly depressed plasma ions and osmolality relative to fish sampled upon capture. Plasma lactate did not differ among groups. Collectively, these results suggest that a 24h recovery in net pen following angling failed to promote post-release survival experienced with immediate release after angling or beach seining.
Article
Use of catch and release, a growing aspect of recreational angling, is promoted for most recreational fisheries, including the fishery for the barramundi Lates calcarifer, an iconic sport fish of northern Australia. Landing nets are commonly used to remove fish from the water and to help hold and control fish while hooks or lures are removed before release. We investigated damage to mucus, scales, skin, and fins of 1.0–3.5-kg barramundi that were caught and held for 60 s in two different types of landing net. The two landing nets represented the commonly used knotted-mesh net and the newer knotless net, which has a smaller mesh size and a flat bottom. Both types of landing net caused some injury, such as mucus loss, scale loss, and fin tears. However, use of the knotless, flat-bottomed landing net considerably reduced the occurrence of these injuries. Holding in the knotted net was associated with fin damage scores and dermal abrasion scores that were over four and five times greater, respectively, than the scores associated with holding in the knotless net. No fish died as a result of being handled in either net. These results are similar to those of other studies that investigated smaller fish. The effects of these injuries on fish survival are discussed.