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We evaluate the utility of an inexpensive, portable recovery bag designed to facilitate recovery of fish from capture stress by combining physiological assays, biotelemetry, and social science surveys. Adult migrating Pacific salmon (Oncorhynchus spp.) were used as a model, since some of their populations are threatened. While catch-and-release is common, there is a need to ensure that it is sustainable. A social science survey revealed that anglers generally have positive attitudes towards recovery bag use, particularly if research identifies that such techniques could be effective. Physiological assays on pink salmon (Oncorhynchus gorbuscha) revealed benefits of both high- and low-velocity recovery, but high velocity was most effective with reduced plasma cortisol concentrations and similar plasma sodium and chloride concentrations as those found in controls at all recovery durations. A biotelemetry study on sockeye salmon (Oncorhynchus nerka) captured by anglers and stressed by air exposure then placed in recovery bags had 20% higher, but not significantly different, survival than no-recovery salmon. The integration of natural science and social science provides an important step forward in developing methods for promoting recovery of fish from capture.
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Evaluation of a simple technique for recovering fish from capture
stress: integrating physiology, biotelemetry, and social science to solve
a conservation problem
M.R. Donaldson, G.D. Raby, V.N. Nguyen, S.G. Hinch, D.A. Patterson, A.P. Farrell, M.A. Rudd, L.A. Thompson, C.M. O'Connor, A.H. Colotelo,
S.H. McConnachie, K.V. Cook, D. Robichaud, K.K. English, and S.J. Cooke
Abstract: We evaluate the utility of an inexpensive, portable recovery bag designed to facilitate recovery of fish from capture stress
by combining physiological assays, biotelemetry, and social science surveys. Adult migrating Pacific salmon (Oncorhynchus spp.) were
used as a model, since some of their populations are threatened. While catch-and-release is common, there is a need to ensure that it
is sustainable. A social science survey revealed that anglers generally have positive attitudes towards recovery bag use, particularly if
research identifies that such techniques could be effective. Physiological assays on pink salmon (Oncorhynchus gorbuscha) revealed
benefits of both high- and low-velocity recovery, but high velocity was most effective with reduced plasma cortisol concentrations and
similar plasma sodium and chloride concentrations as those found in controls at all recovery durations. A biotelemetry study on
sockeye salmon (Oncorhynchus nerka) captured by anglers and stressed by air exposure then placed in recovery bags had 20% higher, but
not significantly different, survival than no-recovery salmon. The integration of natural science and social science provides an
important step forward in developing methods for promoting recovery of fish from capture.
Résumé : Nous évaluons l'utilité d'un sac de récupération portable et peu dispendieux pour ce qui est de favoriser la récupération
de poissons après un stress de capture, en combinant des essais physiologiques, des données de biotélémétrie et des études
sociologiques. Des saumons du Pacifique (Oncorhynchus spp.) adultes en migration ont été utilisés comme modèle étant donné que
certaines de leurs populations sont menacées et que, bien que la pêche avec remise a
l'eau soit répandue, il importe de vérifier
qu'il s'agit d'une pratique durable. Une étude sociologique a révélé que les pêcheurs a
la ligne voient généralement d'un bon œil
l'utilisation d'un sac de récupération, en particulier si la recherche établit l'efficacité de telles méthodes. Des essais physi-
ologiques sur des saumons roses (Oncorhynchus gorbuscha) ont révélé que la récupération tant a
haute vitesse qu'a
basse vitesse
présentait des avantages, mais que la récupération a
haute vitesse était plus efficace, se traduisant par une réduction des
concentrations de cortisol plasmatique et des concentrations semblables de sodium et de chlorure, utilisées comme témoins,
pour toutes les durées de récupération. Dans une étude biotélémétrique, des saumons sockeye (Oncorhynchus nerka) capturés par
des pêcheurs a
la ligne et soumis au stress de l'exposition a
l'air, puis placés dans des sacs de récupération présentaient un taux
de survie de 20 % supérieur a
celui des saumons n'ayant pas récupéré, bien que cette différence ne soit pas significative.
L'intégration des sciences naturelles et de la sociologie a donc permis une importante avancée dans la mise au point de méthodes
favorisant la récupération de poissons suite a
leur capture. [Traduit par la Rédaction]
Conservation physiology has emerged as a field that uses phys-
iological tools and knowledge to inform conservation and man-
agement initiatives (Wikelski and Cooke 2006). One of the current
limitations of conservation physiology is that physiological re-
search is often disconnected from conservation practitioners and
managers (Cooke and O'Connor 2010), but positive examples of
using physiological knowledge to improve fisheries management
are beginning to emerge (e.g., Cooke et al. 2012). Here, we use a
novel approach by combining natural science and social science
research in the Pacific salmon (Oncorhynchus spp.) recreational an-
gling fishery, a highly relevant system given the precarious status
of some Pacific salmon populations (Jonsson et al. 1999; Irvine
et al. 2005; Gustafson et al. 2007). We assess the utility of facili-
tated recovery techniques, i.e., methods of expediting physiolog-
ical recovery and promoting survival following fisheries capture
stress, by combining a social science survey, an assessment of
physiological condition, and a determination of survival to reach
spawning areas. Given the applied nature of this research and the
importance of stakeholder opinion, we begin by conducting a
social science survey of recreational anglers, then follow up this
work with a laboratory-based physiology study and a field-based
telemetry survival study.
Pacific salmon are targeted by recreational fisheries during the
marine and freshwater phases of their spawning migrations. As
an example, the Canadian sockeye salmon (Oncorhynchus nerka)
recreational fishery in Fraser River, British Columbia, has grown
in recent years (Kristianson and Strongitharm 2006) despite some
Received 11 May 2012. Accepted 10 September 2012.
Paper handled by Associate Editor Deborah MacLatchy.
M.R. Donaldson* and S.G. Hinch. Department of Forest Sciences, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
G.D. Raby, V.N. Nguyen, C.M. O'Connor, A.H. Colotelo, S.H. McConnachie, K.V. Cook, and S.J. Cooke. Department of Biology and Institute of Environmental
Science, Carleton University, Ottawa, ON, Canada.
D.A. Patterson and L.A. Thompson. Fisheries and Oceans Canada, Cooperative Resource Management Institute, Simon Fraser University, Burnaby, BC, Canada.
A.P. Farrell. Department of Zoology and Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, Canada.
M.A. Rudd. Environment Department, University of York, Heslington, York, UK.
D. Robichaud and K.K. English. LGL Limited, Sydney, BC, Canada.
Corresponding author: M.R. Donaldson (e-mail:
*Present address: 2424 Main Mall, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Can. J. Fish. Aquat. Sci. 70: 90–100 (2013)
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populations being considered endangered, owing in part to
mixed-population fishing (e.g., Cultus Lake sockeye salmon; Rand
2008). This fishery is traditionally catch-and-keep, but anglers may
choose to voluntarily release fish if they are over their quota or if
the fish is undesirable. The release-to-keep ratio can be as high as
1:2 for Fraser River sockeye salmon, which translates to high num-
bers when fish are in high abundance (e.g., 100 000 released versus
200 000 harvested in 2010; Fisheries and Oceans Canada 2010) and
postrelease mortality is known to occur (Donaldson et al. 2011).
While released fish may resume their migrations without delay,
individuals showing signs of exhaustion at the time of release
(e.g., loss of equilibrium, inability to swim against current, and
(or) physiologically compromised) may potentially drift down-
river and be prone to capture by predators or secondary fisheries
(e.g., subsequent capture by a gill net). In such cases, specially
designed recovery gear that ram ventilates the gills could assist
physiological recovery and allow fish to more quickly and effec-
tively resume migration. However, recovery techniques would
require acceptance from stakeholders and scientific evidence
of their effectiveness before they could be considered for im-
Human dimensions research and conservation social science
(e.g., Mascia et al. 2003) are increasingly being used to inform
policy and management actions, in particular to help in under-
standing the factors that influence compliance with conservation
regulations (Rudd et al. 2011a). While understanding socio-
ecological dynamics has been suggested as an important part of
ensuring sustainable recreational fisheries management (Post
et al. 2008; Hunt et al. 2011), and important examples of collabo-
rations between the angling community and scientists have oc-
curred (e.g., Tufts and Morlock 2004; Danylchuk et al. 2011), the
viability of facilitated recovery methods has not been examined
interactively from the dual perspectives of the social and natural
sciences. In fact, few management agencies throughout North
America have considered facilitated recovery methods in freshwa-
ter recreational fisheries (Pelletier et al. 2007), likely owing to the
limited data available on their effectiveness. If facilitated recovery
were to be considered for implementation, an understanding of
recreational angler perspectives on the issue of facilitated recov-
ery gear would help fisheries managers to determine whether
such gear could be readily adopted by anglers.
The physiological response of fish to capture stress is generally
considered analogous to exercise stress and has been well charac-
terized in the fish physiology literature (Milligan 1996; Kieffer
2000). The time required to clear metabolites from the blood and
restore muscle energy stores may limit subsequent performance,
since this recovery rate will determine the frequency of maximal
performance (Milligan 1996). Prolonged recovery may lead to ter-
tiary consequences, including delayed mortality (Black 1957;
Wood et al. 1983). Prior to the work of Milligan (1996) and Milligan
et al. (2000), the physiological time course of recovery from exer-
cise stress was thought to be long, requiring 4 h for recovery of
oxygen consumption (Brett 1964) and even longer for metabolites
to return to prestress conditions (Black 1957; Turner et al. 1983).
Most early studies measured recovery in static (i.e., no velocity)
water, but Milligan et al. (2000) found that when rainbow trout
(Oncorhynchus mykiss) recovered in flowing water with a constant
low-velocity current (i.e., 0.9 body lengths per second), complete
metabolic recovery was much quicker (2 h) relative to static
water recovery. Subsequent work suggests that low-speed swim-
ming during recovery from exhaustive exercise can improve swim
performance in subsequent swimming tests in juvenile salmonids
(Kieffer et al. 2011).
The results of Milligan et al. (2000) have been adapted to facili-
tate physiological recovery and improve survival of coho salmon
(Oncorhynchus kisutch) captured by various marine fisheries (Farrell
et al. 2000; Farrell et al. 2001a, 2001b). Farrell et al. (2001b) found
that placing troll-captured coho salmon in a cage towed alongside
the fishing vessel promoted accelerated physiological recovery. A
revival box (i.e., Fraser Box) used on board a commercial gill net
boat that jetted seawater towards confined individual fish pro-
moted rapid physiological recovery within 1–2 h, restored swim-
ming ability, and improved survival even for fish that appeared
moribund at capture (Farrell et al. 2001a). The general physiolog-
ical principle involved in these studies is that recovery is facili-
tated by assisted gill ventilation by ramming water velocity into
the mouth and across the gills of recovering fish and (or) main-
taining steady swimming during the recovery process, although
recent work by Kieffer et al. (2011) suggests that the former may be
the more likely mechanism. The marine studies by Farrell et al.
(2001a, 2001b) involved large vessel-based apparatus, and survival
was determined by observing fish in net pens for 24 h. There have
been no investigations of this kind in freshwater environments or
with recovery gear that is more portable and thus could be used by
recreational salmon fishers, despite recent findings for delayed
mortality of fish released following angling capture (Donaldson
et al. 2011). Biotelemetry is a useful tool to track long-term survival
of individuals caught and released from fisheries (Donaldson et al.
The objective of the present study was to test the utility of a
simple, inexpensive, and portable example of facilitated recovery
gear, herein referred to as a recovery bag (Fig. 1). Recovery bags are
structured cylindrical hypolon bags with mesh ends that are sub-
merged in high-velocity water to enable flow through the bag and
over the fish's mouth and gills, resulting in ram ventilation akin
to the Fraser box tested by Farrell et al. (2001a). The purpose of the
recovery bags is to provide an environment where the exhausted
fish can be oriented into the flow of water without risk of drifting
downriver and being susceptible to injury, predation, or fisheries
capture. Recovery gear in general requires relatively high water
velocities to be effective, but recovery bags have the added benefit
of being portable and not requiring an external power source,
which is ideal for recreational anglers and shore-based net fisher-
ies, such as Native fisheries.
We aimed to test the utility of recovery bags for facilitating the
recovery of Pacific salmon following capture in freshwater using a
three-pronged approach. First, we surveyed salmon anglers to as-
sess the potential for implementing recovery techniques in a Pa-
cific salmon recreational fishery. Second, we assessed the
effectiveness of recovery bags on the physiological response of
adult pink salmon (Oncorhynchus gorbuscha) following a catch-and-
release simulation. Third, we used biotelemetry to determine
whether recovery bags influenced the survival of sockeye salmon
Fig. 1. A schematic of a facilitated recovery bag attached to a
reinforcing bar to secure the bag to the substrate. Fish are placed
into the bag and oriented into the water flow. Wide mesh ends of
the bag enable sufficient water velocity to pass through the fish's
mouth and gills. The zippered opening enables fish exit the bag
with minimal disturbance and without additional handling.
Direction of water
Water surface
Recovery bag
Reinforcing bar
to secure
recovery bag to
Mesh end to
enable water
opening for
rapid, hands-
free release
Donaldson et al. 91
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released by recreational anglers. These three components were
integrated to discuss the application of portable recovery gear in
the management and conservation of Pacific salmon in the con-
text of freshwater recreational salmon fisheries.
Materials and methods
Angler social science survey
Experimental design
The purpose of the angler survey was to determine whether
recreational anglers participating in a fishery for Pacific salmon
would be willing to consider the use of facilitated recovery gear
for fish that are caught with the intention of being released. We
surveyed anglers participating in the Fraser River sockeye salmon
recreational fishery. Face-to-face interviews with anglers were
conducted at fishing sites and boat launches of the lower Fraser
River between 30 July and 27 August 2010. Sixty-seven anglers
participated in our survey. Our mixed-method research approach
(i.e., both quantitative ratings data and open-end responses were
collected) used semistructured interviews lasting 1050 min
(Creswell 2009) in which key questions prompted structured con-
versations between interviewer and interviewee (Table 1). During
the interview period, anglers were targeting sockeye salmon, but
the survey was designed to ask questions in general about facili-
tated recovery for Pacific salmon and did not focus on one specific
Statistical analysis
Latent-class (LC) cluster analysis (Magidson and Vermunt 2004)
can be used to statistically identify LC membership using infor-
mation from a set of observed variables (indicators) that imper-
fectly measure underlying true class membership (e.g., Rudd et al.
2011b). In our LC models, indicator variables, based on our catego-
rization of qualitative responses to four sets of questions about
recovery bag use, were used to estimate a latent variable, “sup-
porters of recovery bag program implementation”. The LC models
based on qualitative attitudinal data allowed us to characterize LC
clusters whose members have statistically homogeneous beliefs
or preferences regarding recovery bag use within clusters, but
maximal difference between clusters. We used the Akaike infor-
mation criterion (AIC) to identify the most parsimonious LC
model by choosing a final LC model with the number of clusters
that minimized AIC. We also tested for local independence be-
tween indicators using bivariate residual statistics (e.g., Rudd
et al. 2011b). Significant bivariate residuals (
> 3.84, df = 1,
P < 0.05) signify local dependence between variables and function-
ally mean that two or more indicators provide redundant infor-
mation for the clustering process. We used Latent GOLD 4.0
(Vermunt and Magidson 2005) for all analyses.
Facilitated physiological recovery
Study site and animals
Experiments were conducted at Fisheries and Oceans Canada's
Weaver Creek Spawning Channel (49°32=N, 121°88=W) in British Co-
lumbia, Canada, an artificial channel draining into the Harrison
River, a lower Fraser River tributary. Water temperatures during the
study ranged between 10 and 12 °C. Only females were used in this
experiment because sex-specific differences are known to occur in
certain physiological variables (e.g., plasma cortisol; Donaldson et al.
2010a). Fish were selected upon first arrival at the spawning chan-
nel. Fish were showing signs of secondary sexual characteristics
but none were reproductively mature (i.e., not ripe). Pink salmon
are targeted by fisheries and co-migrate with other Pacific salmon
species that are of conservation concern in the Fraser River (e.g.,
interior coho and Cultus Lake sockeye salmon), but are not a
species of concern themselves.
Experimental design
Individuals were randomly assigned to controls or no-, low-, or
high-velocity treatments. Controls (n = 8) were immediately
placed into individual holding boxes (length × width × depth of
93.7 cm × 54.0 cm × 47.3 cm) and held for 24 h before blood
samples were taken. Each holding box was supplied with fresh
water (0.63 L·s
) pumped from the spawning channel. Fish from
the no-, low-, or high-velocity treatments were individually trans-
ferred into a donut-shaped exercise tank (diameter 150 cm, water
depth 40 cm) supplied with fresh water pumped from the spawn-
ing channel, where they were manually chased for a period of
3 min (coaxed by three experimenters positioned around the ex-
ercise tank to burst swim for 3 min (Black 1958; Wood 1991)to
simulate an angling capture event), then given 1 min air exposure
using previously described methods (Donaldson et al. 2010a), sim-
ulating gear removal in air or photography.
Recovery bags are particularly relevant where fish are ex-
hausted to the point where they have lost equilibrium or are
unable to swim to locations that are free from predators or loca-
tions of optimal flow conditions. Here, fish were visibly exhausted
following the exercise and air exposure treatments, typically un-
able to engage in burst swimming and (or) having difficulty main-
taining equilibrium. Fish assigned to the low-velocity (n = 75) or
high-velocity (n = 75) group were transferred to one of three recov-
Table 1. Latent class membership profile for two-class recovery bag support model.
Latent-class cluster Supporters (%) Nonsupporters (%)
Overall cluster size 53.8 46.2
Indicator variables
1. What do you think about the idea of a revival bag to help incidental [salmon] catches?
(a) Negative (protest, legitimate) 13.1 78.6
(b) Neutral 0.1 10.7
(c) Positive (conditional, fully) 86.8 0.3
2. Is there a need for a recovery bag to revive incidentally caught salmon?
(a)No 39.8 98.0
(b) Neutral 9.1 0.3
(c) Yes 51.1 1.8
3. If the bag was shown to improve survival of released salmon, would you use it on a voluntary basis?
(a)No 15.5 54.1
(b) Yes 84.5 45.9
4. Suppose using a recovery bag was mandatory for reviving fish before releasing it.
What are your thoughts on that?
(a) Negative (protest, legitimate, conditional) 0.6 35.4
(b) Other/Neutral 0.1 7.2
(c) Supportive (compliant, conditional, fully) 96.3 57.4
92 Can. J. Fish. Aquat. Sci. Vol. 70, 2013
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ery bag types. The recovery bags were fine (1 cm mesh size) or
coarse mesh (5 cm mesh size) made from Hypalon and cylindrical
in shape (length of 100 cm, diameter of 20 cm) or were simple
drawstring mesh sacks (length × width = 80 cm × 40 cm). Bags were
positioned in the natural water current of the spawning channel
and attached by rope to a structure at the side of the channel to
ensure that the bag remained stationary and that the position of
the bag did not change during the recovery period. The low-
velocity group was placed in a location with a water current of
0.19 m·s
, and the high-velocity group was placed in a location
with a current of 0.43 m·s
. Velocities inside the fine and coarse
mesh bags in the low-velocity group were 0.15 and 0.17 m·s
respectively, and within the fine and coarse mesh bags in the
high-velocity group 0.35 and 0.39 m·s
, respectively (mean rates).
For comparison, within the Weaver Creek Spawning Channel,
mean current velocity has been measured at 0.4 m·s
et al. 2011). During the present study, velocities measured in areas
of the spawning channel where fish typically maintained position
averaged 0.18 m·s
. Fish assigned to the no-velocity group (n = 22)
were transferred into individual holding boxes (as described
above) for recovery and blood sampling.
We chose three time points of <60 min to provide a range of
realistic times in which anglers might be willing to remain in the
same location as the bag (i.e., enabling them to continue to fish)
while the fish in the bag had time to recover.
Single blood samples were taken after 15, 30, or 60 min of recovery.
For blood sampling, individuals were collected from bags, placed
supine in a water-filled, V-shaped foam-padded sampling trough
(Cooke et al. 2005), and blood sampled immediately. Individuals
were only blood sampled once. The duration of the entire proce-
dure was <2 min. Fork length (FL) was also measured. Each blood
sample collected 2.5 mL blood by caudal puncture using a 3.8 cm,
21-gauge needle and a heparinised vacutainer (3 mL lithium hep-
arin, Becton-Dickinson, Franklin Lakes, New Jersey), and then
stored in ice-chilled water for 1 h until subsequent processing.
Physiological assays
The chilled 2.5 mL blood samples were centrifuged at 7000g
for 3 min, and plasma was stored in liquid nitrogen prior to being
frozen at 80 °C until analysis. Plasma was subsequently analysed
for cortisol (Neogen ELISA with Molecular Devices Spectramax
240pc plate reader), lactate, glucose (YSI 2300 STAT Plus analyser),
osmolality (Advanced Instruments 3320 freezing point osmome-
ter), chloride (Haake Buchler digital chloridometer), and sodium
and potassium (Cole-Parmer, model 410 single channel flame pho-
tometer; Farrell et al. 2001b).
Statistical analysis
Normality was assessed using Shapiro–Wilk tests, homogeneity of
variance was assessed using Levene's test, and variables were log
transformed to reduce heteroscedasticity where necessary, but all
data are presented as nontransformed values. Three-way multivari-
ate analysis of variance (MANOVA) was used to test for relationships
among each of the physiological variables with recovery period (15,
30, or 60 min), water velocity (no, low, or high), and bag type (fine
mesh, coarse mesh, or mesh sack), as well as their interactions. Sub-
sequent one-way ANOVA was used to test for differences among
groups at each recovery period, and Bonferroni adjustments were
made, resulting in
= 0.007. Tukey's post hoc tests were conducted
on one-way ANOVA results (
= 0.05). Statistical analyses were per-
formed in JMP version 9.0 (SAS Institute 2011).
Facilitated recovery and survival to reach spawning areas
Study site and experimental design
Experimental procedures were conducted on sockeye salmon at
the Fraser River at Grassy Bar, near Chilliwack, British Columbia,
Canada, between 9 and 26 August 2010 (Fig. 2). Treatment groups
were established as follows: (1) angling; (2) angling plus 1 min of
air exposure; (3) angling plus recovery; (4) angling plus 1 min of air
exposure plus recovery; and (5) beach seine. Volunteer anglers
captured sockeye salmon using standard bottom-bouncing gear
from either the shore or boats anchored near the shore
(Donaldson et al. 2011). Capture durations ranged between 1 and
5 min. Once landed, hooks were removed and individuals were
randomly assigned to a treatment. Fish in the angling-only treat-
ment were tagged for radio telemetry and released immediately,
while those in the angling and air exposure treatment were given
a 1 min air exposure by holding the fish by hand out of the water,
then being tagged for radio telemetry and released to resume
their migrations.
For the angling recovery groups, fish were likewise either as-
signed to no air exposure or air exposure. Individuals were then
tagged for radio telemetry and placed in mesh-ended Hypalon
bags for a 15 min recovery period. The mean velocity in this area
was 0.11 m·s
, which is closer to our “low-velocity” treatment
from the pink salmon study rather than the “high-velocity” treat-
ment. However, this was the highest and most consistent water
velocity available at the study site. Bags were positioned to ensure
that the current was directed through the bag and that fish were
oriented in the bag anteriorly to direct the flow of river water over
the fish's mouth and gills. Following the recovery period, individ-
uals were guided out of the bag, with minimal physical touching
by technicians, and back into the river to resume their migra-
tions. For the beach seine capture group, fish were captured using
a64m×7.5m×5cmmesh beach seine net. Technicians contin-
ually monitored the catches from both capture methods and re-
corded qualitative information about angling durations, air
exposure durations, injuries (e.g., hooking location and degree of
bleeding), and general condition descriptions.
Telemetry methods and determination of survival
A total of 173 sockeye salmon were radio telemetry tagged for
this study. Individuals from each treatment were tagged and re-
leased in equal proportions during the study period. Established
protocols for the gastric tagging of sockeye salmon were used,
where tags were inserted through the mouth and into the stom-
ach of each individual, since they do not feed during their migra-
tions and their stomachs close around and secure the tag
following placement (Cooke et al. 2005). Coded radio transmitters
(MCFT-3A-3 V, Lotek Wireless Inc., Newmarket, Ont., or Pisces 5,
Sigma-Eight Inc., Newmarket, Ontario) were used. Coded trans-
mitters enabled the identification of individual fish as they were
detected at receiver stations. For all fish, a scale sample and a 0.5 g
adipose fin clip were taken for identification of population com-
plexes, and FL measurements were made and a numbered cinch
marker tag (Floy Tag and Mfg., Inc., Seattle, Washington, USA) was
attached through the dorsal musculature. Procedures were always
completed in ≤2.5 min.
Twenty-eight radio telemetry receiver stations (SRX400 or
SRX400A, Lotek Wireless Inc.) with three- or four-element Yagi
antennas (Maxrad Inc., Hanover Park, Illinois, USA, or Grant Sys-
tems Engineering Inc., King City, Ontario) were strategically posi-
tioned throughout the Fraser River watershed (Donaldson et al.
2010b; Donaldson et al. 2011). Owing to their high fidelity to natal
spawning areas, DNA stock identification enabled us to determine
the natal subwatershed that each individual was migrating to.
Arrival at natal subwatershed was determined by detection with
fixed station telemetry receivers located in tributaries en route to
spawning grounds. Failure of an individual to be detected at sub-
sequent receiver locations was termed en route mortality (Don-
aldson et al. 2011). Individuals that were reported as fisheries
harvest were excluded from this study.
Statistical analyses
One-way ANOVA was used to test for differences in FL among
treatment groups. Pearson
analysis was used to test for differ-
Donaldson et al. 93
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ences in postrelease survivorship among treatment groups. Be-
cause sex could not be determined visually (i.e., fish were not
showing secondary sexual characteristics), sex could not be reli-
ably included as a factor in analysis. All values presented here
represent means ± standard error (SE), unless otherwise noted.
Statistical analyses were performed in JMP version 9.0 (SAS Insti-
tute Inc., Cary, North Carolina, USA).
Angler social science survey
Responses to the question “What do you think about the idea of a
revival bag to help incidental [salmon] catches?” are shown in Fig. 3a.
We found that 39.7% provided negative but legitimate responses:
they were unsupportive of recovery bags as a catch-and-release
tool, but for potentially legitimate reasons (e.g., they questioned
their effectiveness or thought they were unnecessary when fish
were handled properly). Interestingly, 29.4% were conditionally
supportive of the concept (e.g., recovery bags might be used if
mandated, if they were shown to be useful, for beginners only).
We found that 23.5% were fully supportive of the use of recovery
bags as a tool to help reduce catch-and-release mortality of
salmon. When asked explicitly, 66.7% of respondents did not
think there was a need for recovery bags. A total of 66.2% re-
sponded “yes,” that they would use a recovery bag voluntarily.
When asked “Suppose using a recovery bag was mandatory for
reviving fish before releasing it what are your thoughts on
that?”, responses were split among negative protest responses
(10.8%), negative but legitimate responses (7.7%), supportive owing
to compliance (with mandatory use regulations) responses
(35.4%), conditionally supportive responses (10.8%), and fully sup-
portive responses owing to the benefits for released salmon
(30.8%; Fig. 3b).
A two-class model of indicator questions minimized AIC and
there were no significant bivariate residuals, suggesting that all
anglers cleaved into two clusters with internally homogeneous
perspectives regarding recovery bag use (Table 1). Wald tests indi-
cated that the coefficients for only two indicator questions were
jointly significantly different than zero: “angler thoughts on idea
Fig. 2. A map of the Fraser River, British Columbia, Canada, showing locations of fixed station radio telemetry receivers. Receiver locations
are denoted as follows: A, Crescent Island; B, Mission North; C, Mission South; D, Harrison Confluence; E, Weaver; F, Rosedale; G, Hope;
H, Qualark; I, Sawmill; J, Hells Gate; K, Thompson Confluence; L, Spences Bridge; M, Ashcroft; N, North Thompson; O, Timbers House; P, Little
River; Q, Adams River; R, Lower Shushwap; S, Seton Confluence; T, Bridge River; U, Kelly Creek; V, Chilcotin Confluence; W, Farwell Canyon;
X, Chilko; Y, Quesnel Confluence; Z, Likely; AA, Nechako Confluence; BB, Stuart Confluence.
Release site
100 km
94 Can. J. Fish. Aquat. Sci. Vol. 70, 2013
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of recovery bag” (Wald = 10.14, P 0.01), and “voluntary use of
bag,” (Wald = 6.07, P 0.05). The first cluster, which constituted
53.8% of the sample, included respondents who demonstrated
positive attitudes towards recovery bags and greater support for
mandatory implementation and use of bags. The remaining 46.2%
did not see a need for a recovery bag, though almost half of re-
spondents would use it on a voluntary basis if the recovery bag
was shown to increase salmon survival.
Facilitated physiological recovery
MANOVA revealed a significant whole model for log
transformed plasma physiological variables and recovery period, ve-
locity, and bag type (Wilk's = 0.124; F
= 2.497; P < 0.001).
Significant effects were found for recovery period (Wilk's = 0.581;
= 5.308; P < 0.001) and velocity (F
= 11.163; P < 0.001), but
not for bag type (Wilk's = 0.861; F
= 1.323; P = 0.194) or its
interactions. Mean FL was 50.2 ± 1.9 cm and did not differ among
treatments (two-way ANOVA with recovery period and water velocity
as effects; whole model F
= 1.45; P = 0.179).
High and low water velocity with a recovery bag was more
effective than no water velocity in mitigating simulated capture
stress and was influenced by recovery period. For the 15 min re-
covery period, one-way ANOVA testing for differences among ve-
locity groups revealed significant differences for plasma lactate
= 242.600; P < 0.001), sodium (F
= 6.309; P < 0.001),
chloride (F
= 7.173; P < 0.001), potassium (F
= 16.304;
P < 0.001), osmolality (F
= 62.144; P < 0.001) and cortisol (F
26.925; P < 0.001), but not glucose (P > 0.05; Fig. 4). Similarly, for
the 30 min recovery period there was a significant effect of veloc-
ity on plasma lactate (F
= 253.972; P < 0.001), sodium (F
5.785; P < 0.001), potassium (F
= 19.298; P < 0.001), osmolality
= 35.759; P < 0.001) and cortisol (F
= 22.514; P < 0.001), but
not for either glucose or chloride (both P > 0.05). For the 60 min
recovery period, there were significant differences among no-,
low-, and high-velocity types in plasma lactate (F
= 258.412;
P < 0.001), potassium (F
= 6.944; P < 0.001), osmolality (F
17.105; P < 0.001), and cortisol (F
= 27.385; P < 0.001), but not for
either glucose, sodium, or potassium (all P > 0.05). Thus, high-
velocity recovery emerged as the most effective treatment, with
reduced plasma cortisol concentrations relative to the low-
velocity group at 15 and 60 min postcapture, and similar plasma
sodium and chloride concentrations as control values at all recov-
ery periods. For most recovery periods measured, plasma glucose
and potassium concentrations did not differ from control values.
Facilitated recovery and survival to reach spawning areas
Beach seine had the highest survival (57.5%), followed by an-
gling plus air exposure plus recovery (50.0%), angling plus no
recovery (30.8%), angling plus air exposure plus no recovery
(28.6%), and angling plus recovery (16.7%). We did not have a beach
seine recovery group in this study. Significant differences were
found for survival to natal subwatersheds among treatment
groups (
= 15.688; df = 4; P = 0.004), with the beach seine group
having the highest survival. An analysis of survival between the
beach seine, angling, and angling plus air exposure groups with
the recovery groups excluded revealed that beach seine had sig-
nificantly higher survival relative to the two angling groups with
no recovery (
= 7.379; df = 2; P = 0.025). With the beach seine
group excluded from the analysis and only the four angling
groups compared, differences were not observed (
= 6.660; df =
3; P = 0.084; Fig. 5). FL did not differ among treatment groups
= 0.514; P = 0.726).
Potential for recovery bag use by anglers
Our survey found that an equal proportion of anglers have gen-
erally positive attitudes towards recovery bags and support their
implementation compared with the group that does not believe
there is a need for recovery. The fact that one-quarter of survey
respondents were fully supportive of using recovery bags when
asked directly is encouraging, particularly since supporters show
overwhelming support for recovery bag use if scientific evidence
for their effectiveness were presented to them. While non-
Fig. 3. Fraser River salmon angler responses to social science surveys on the support for using facilitated recovery gear to promote recovery
of caught-and-released salmon. Panel (a) shows responses to the question, “What do you think about the idea of a revival bag to help
incidental [salmon] catches?” Panel (b) shows responses to the question, “Suppose using a recovery bag was mandatory for reviving fish before
releasing it what are your thoughts on that?”
Donaldson et al. 95
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Fig. 4. Plasma variables measured in adult pink salmon (Oncorhynchus gorbuscha) following an exercise treatment and a variable recovery
period (15, 30, or 60 min) in portable recovery gears under no (black bars), low (light grey) or high (dark grey) water velocity and controls
(white bars). Different recovery bag types were pooled for analyses as bag type did not emerge as a significant effect in whole model
MANOVAs. Asterisks (*) denote the group differs significantly from control values. Dissimilar letters denote differences among groups at each
recovery period.
96 Can. J. Fish. Aquat. Sci. Vol. 70, 2013
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supporters may still not agree unanimously with using recovery
bags, that group was also more positive towards the use of recov-
ery bags if they were presented with evidence of their effective-
ness. Collectively, the social science survey showed that while
some stakeholders were directly supportive of recovery bags,
most respondents would like to see scientific evidence of their
effectiveness before supporting their use. The rationale behind
conducting the social science surveys was to determine whether
anglers would even be willing to use recovery gear if evidence
existed that such techniques could be beneficial to released fish.
This is important because conflict between recreational angling
communities and managers have been described previously (e.g.,
Danylchuk et al. 2011), and determining whether the bags would
even be hypothetically used in practice was a necessity before
proceeding with the physiology and telemetry components. Given
the generally positive attitudes, the laboratory and field experi-
ments discussed below are certainly relevant towards assessing
the utility of recovery gear in practice.
Facilitated physiological recovery
The capture simulation resulted in pink salmon mounting a
major stress response, typical of exercise stress (Milligan 1996).
The combined exercise and air exposure treatment resulted in
fish generally showing signs of fatigue, including equilibrium loss
and inability to burst swim following the treatment. As a conse-
quence many fish were unable to engage in normal swimming
after treatment and likely would have drifted downstream of the
study area if they had not been placed immediately in recovery
bags. At 15 min, the high velocity resulted in reduced plasma
cortisol concentrations relative to the non-recovery group, a re-
sult consistent with previous studies of rainbow trout (Milligan
et al. 2000) and coho salmon (Farrell et al. 2001a, 2001b). Recovery
using high water velocity was the only treatment where sodium
and chloride concentrations consistently remained unchanged,
further supporting the superiority of this velocity for recovery.
This is an important result for anadromous fish that had recently
undergone a shift in osmoregulatory physiology upon transition
from marine to freshwater environments. Impaired osmoregula-
tory function has been linked with the initiation of rapid senes-
cence and premature death in sockeye salmon (Hruska et al. 2010),
and plasma chloride concentrations can correlate strongly with
longevity for this species (Jeffries et al. 2011). Plasma potassium did
not differ between control and recovery treatments for the 15 and
30 min recovery periods. Exercise can result in increased plasma
potassium as this ion is lost from muscle (Sejersted and Sjøgaard
2000), but we found that plasma potassium was unchanged rela-
tive to treatment. Likewise, plasma glucose was the same among
groups and recovery periods and fell in the range measured in
adult coho salmon captured by dip net from hatchery raceways
(56 mmol·L
, Donaldson et al. 2010a) and sockeye salmon cap-
tured by hook-and-line or net and sampled rapidly (6–7 mmol·L
Donaldson et al. 2011), both in freshwater. These results suggest
that facilitated recovery was generally effective at reducing the
cortisol response and maintaining ion–osmoregulatory balance
and metabolic state, although plasma lactate remained elevated
Despite a positive effect of recovery bags for some parameters
measured, recovery was not complete to the extent observed for
rainbow trout in the laboratory by Milligan et al. (2000). Kieffer
et al. 2011 reported that metabolic recovery of brook trout was not
expedited for fish swimming at certain speeds, although they did
observe that fish with access to higher flows swam for longer
periods of time during a swimming challenge and that fish had a
tendency to move towards areas of higher flow after exercise
stress. Likewise, Farrell et al. (2001b) found that adult coho salmon
placed in Fraser recovery boxes for 1 or 2 h had only a partial
recovery of muscle metabolites and that plasma metabolites and
indices of stress and ion–osmoregulatory balance did not recover.
Increased plasma osmolality and lactate as observed in our study
are typical postexercise, owing to a decrease in muscle and blood
pH caused by lactic acid dissociation (Wang et al. 1994), which in
turn disrupts ion–osmoregulatory balance as water shifts from
blood to muscle (Wood 1991). Plasma cortisol concentration, even
in our most effective high-velocity treatment, was still 2.5-fold
higher than in controls, but still much lower than in our no-
velocity group. Plasma cortisol concentration in the present study
was also lower than that for coho salmon followinga1or2h
recovery in a Fraser box (i.e., 380–1270 ng·mL
(Farrell et al.
2001b). The generally high plasma cortisol values are expected,
since this parameter tends to be higher in the final stages of
reproductive maturation for Pacific salmon and can vary greatly
by sex, with females typically having higher circulating values
(Sandblom et al. 2009; Donaldson et al. 2010a).
Facilitated recovery and survival to reach spawning areas
Aside from the beach seine only treatment that was included
for reference, the air exposed recovery treatment represents the
highest survival of the angling groups. These survival results must
be interpreted cautiously, since the significant differences ob-
served in this comparison appear to have been driven by the
beach seine group, likely owing to the low number of individuals
reaching spawning areas for some of the angling groups. Even
still, the recovery bag treatment resulted in >20% higher survival
relative to immediately released fish for the air exposure group,
suggesting that this method could benefit fish exposed to air. The
nearly twofold decrease in survival for the non-air exposed group
suggests that care must be exercised when determining which
fish require facilitated recovery and which would instead benefit
from immediate release. This may lend further support to the
recommendations of Farrell et al. (2001b), who suggest immediate
release of individuals in vigorous condition (e.g., capable of main-
taining equilibrium and burst swimming) or perhaps individuals
that underwent less stressful handling (i.e., short duration of air
exposure). In the present study, following the air exposure treat-
Fig. 5. Survival to reach natal subwatersheds for adult sockeye
salmon (Oncorhynchus nerka) captured and released by recreational
anglers in the lower Fraser River, British Columbia, Canada. Angled
fish were either immediately released, placed in a recovery bag for
15 min prior to release, air exposed and immediately released, or air
exposed and placed in a recovery bag for 15 min prior to release.
Beach seine survival is included for comparison and all individuals
from this treatment were immediately released (i.e., none were
given a recovery treatment). Sample sizes for each treatment appear
within the vertical bars.
Donaldson et al. 97
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ment in particular, fish were incapable of burst swimming and
many had difficulty maintaining equilibrium, suggesting that
these individuals may have had short-term difficulty accessing
locations of suitable velocity for recovery of their own volition.
The increased survival for the air-exposed recovery group relative
to the air-exposed immediate release group may be the result of
expedited physiological recovery and reduced metabolic costs as-
sociated with the stressor, as observed by Farrell et al. (2001b).
The survival of beach seine and angling capture groups (52.2%
and 36.3%, respectively) in a study by Donaldson et al. (2011) com-
pare favourably with those identified in our study, which used the
exact same telemetry and experimental methods, but without an
experimental air exposure treatment and without facilitated re-
covery. Interestingly, the beach seine group had higher survival
than either the angling or angling and air exposure groups that
were not given the recovery treatment, providing additional evi-
dence that release following beach seine capture can result in
higher survival for sockeye salmon relative to angling (Donaldson
et al. 2011). To put our survival proportions in context, Martins
et al. (2011) found that sockeye salmon captured in freshwater
environments by either fish wheel or tangle net had survival to
spawning areas ranging between 30% and 50%. However, sockeye
salmon captured and released by purse seine in the marine envi-
ronment had >70% survival from their first detection in the lower
Fraser River to spawning areas (Martins et al. 2011). These marine
tagged individuals may represent the best available telemetry sur-
vival data that approach true baseline survivorship values for the
freshwater migration, since tracking them from river entry (i.e.,
excluding mortalities that occur in the marine environment) en-
ables the exclusion of capture and handling effects that occur in
freshwater environments. Based on this 70% baseline survival
value, we conclude that beach seine capture and release resulted
in 12.5% reduced survival relative to baseline, recovery bag follow-
ing angling and air exposure resulted in 20% reduced survival
relative to baseline, and other treatments resulted in approxi-
mately 40% or greater reduced survival relative to baseline.
Facilitated recovery has the potential to increase postrelease
survival (Farrell et al. 2001a, 2001b), which has great relevance to
freshwater fisheries, where fish may be released or escape from
various fisheries sectors and gear types. While angler response
was not unanimous, respondents were generally supportive of the
possibility of recovery bag use, particularly if there is evidence of
their effectiveness. Engaging anglers early is important because
the method by which the bags are used by anglers will undoubt-
edly influence their effectiveness for recovery. Our physiology
results suggest that the type of bag is less important than the
water velocity itself, since several bag designs resulted in a re-
duced physiological disturbance relative to no velocity, particu-
larly for the 15 min high-velocity group. We found that the 15 min
recovery period with a high water velocity was most effective, and
this seems like a pragmatic time point for anglers. However, in-
ability to find suitable velocity water could be problematic. For
our telemetry study, bags were placed in the highest available
velocity at the site of the study area, but these velocities were still
lower than the optimal “high velocity” treatment from the phys-
iology study. The observed benefit of recovery bags to air-exposed
fish survival suggests that velocities of 0.1 m·s
could still im-
prove survival for fish in poor condition; however, more research
is required to further elucidate the optimal conditions for recov-
ery and the minimum velocities required to promote survival.
Fish in vigorous condition may benefit from immediate release,
whereas those in poor condition (i.e., unable to burst swim or
maintain equilibrium) are more likely to benefit from a short-
duration facilitated recovery, provided that suitable water veloci-
ties can be located.
Directions for future research
Given the promising but not unequivocal results presented
here, additional studies are required to further optimize recovery
methods before such techniques could be used as a conservation
tool in freshwater fisheries. A comparative study that tests differ-
ent water temperatures, water velocities, timing, and recovery
gear type is warranted. With the importance of water velocity in
enhancing recovery, future work might focus on determining op-
timal velocities and exploring bag designs that optimize water
velocity within the bag. Combining laboratory-based (e.g., under
different temperature conditions and water velocities) and field-
based (e.g., telemetry) study designs as we have done here would
be likewise beneficial, since it provides mortality as an endpoint
but also enables greater insight into the mechanisms that may
contribute to mortality.
Use of a light-weight, collapsible bag remains beneficial for this
purpose, since it can be easily transported. However, modifying
Fraser boxes (Farrell et al. 2001b) for portability could be useful for
certain fisheries that are easily accessed by roads and have a high
density of anglers or on-shore net fisheries. Using light-weight
construction materials and portable pumps (e.g., battery or solar
operated) could provide sufficient flow even in low-flow areas.
Given the species-specific nature of the stress response in fish
(Black 1955; Turner et al. 1983), many research opportunities exist
to determine the most effective methods of facilitating recovery
depending on the physiological needs of different species. For
example, low-velocity swimming appears to not enhance recovery
from exhaustive exercise in centrarchids in the way it does for
salmonids. Even within the salmonid family there can be impor-
tant species-specific responses to stress (Pottinger 2010) and recov-
ery (Donaldson 2012), and swimming during recovery from
exercise has been shown to not expedite physiological recovery
for brook trout (Salvelinus fontinalis; Kieffer et al. 2011). Even so, the
general principles of expedited recovery first observed for rain-
bow trout (Milligan et al. 2000) seem to be applicable to at least
some other salmonid species (e.g., Farrell et al. 2001a, 2001b). Fu-
ture work needs to explore how, or whether, facilitated recovery
would be beneficial for species other than the closely related sal-
monid species examined here.
Together, these three studies suggest that recovery bags hold
promise for facilitating physiological recovery and promoting sur-
vival of Pacific salmon captured in fresh water. The generally
positive attitudes towards recovery bag use by anglers, particu-
larly if such techniques were found to be effective, provides ratio-
nale for further exploration of facilitated recovery methods. Our
physiology and telemetry studies provide evidence that recovery
bags have potential for promoting physiological recovery and sur-
vival, respectively, and lay a foundation for enhancing facilitated
methods. Given that recovery bags can be a simple, inexpensive,
and portable means of facilitating recovery, they could be condu-
cive for use in the recreational fishery and, owing to this sector's
similarities with many commercial fisheries (Cooke and Cowx
2006), other small-scale inland fisheries that operate from shore.
Our results provide an important step forward in identifying
methods for promoting recovery from fisheries capture stress,
which has consequences for increasing the sustainability of fresh-
water catch-and-release. This work provides a unique example
where conservation physiology and social science can be inte-
grated to address a management concern, and we hope that other
researchers seek out similar opportunities in the future.
Experiments were approved by The University of British
Columbia Animal Care Committee and the Canadian Council of
Animal Care. Human dimensions surveys were approved by Car-
leton University's Research Ethics Board. Special thanks to
A. Lotto, M. Drenner, C. Whitney, J. Hills, V. Ives, M. Hague,
J.O. Thomas, F. Kwak, D. McKay, and J. Carter for field and lab
98 Can. J. Fish. Aquat. Sci. Vol. 70, 2013
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assistance. We thank R. Stitt, W. Charlie, and Fisheries and Oceans
Canada Weaver Creek Spawning Channel staff. Thanks also to
S. Tyerman and A. Blakely for telemetry logistic support. This
project was funded by a Natural Sciences and Engineering Re-
search Council of Canada (NSERC) Strategic Grant. Additional sup-
port was provided by The University of British Columbia, Carleton
University, Fisheries and Oceans Canada, the Pacific Salmon Com-
mission, the Pacific Salmon Foundation, Public Utility District 2 of
Grant County, Public Utility District 1 of Douglas County, and the
B.C. Ministry of Environment. M.R.D. was funded by an NSERC
Alexander Graham Bell Canada Graduate Scholarship-D3.
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... Support for the efficacy of assisted recovery of fish after capture is mixed. Some studies have demonstrated that retention in recovery RAINBOW TROUT RECOVERY IN COLD WATER devices can facilitate physiological recovery in angled fish (Farrell et al. 2001;Brownscombe et al. 2013;Donaldson et al. 2013), whereas others have not found evidence of improved recovery (Robinson et al. 2013(Robinson et al. , 2015Brownscombe et al. 2017aBrownscombe et al. , 2017b. These differences could be due to variation in angling contexts, species-specific stress tolerances, and the length of time for which the fish are held in recovery devices (Suski et al. 2007;Nguyen et al. 2014;Raby et al. 2015). ...
... Anglers may be hesitant to adopt practices if they are inconvenient or if they require additional costs. Donaldson et al. (2013) conducted a survey of anglers and found that anglers were generally supportive of the usage of recovery bags, a simple assisted-recovery method, and their support increased if research showed that the method was effective. In our case, recovery in the flow box was considerably more involved compared to recovery in the cooler, but the outcomes for fish that were released did not differ significantly provided that recovery was conducted in cool water. ...
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The effectiveness of catch‐and‐release as a conservation practice assumes minimal impacts to released fish. In most cases, angling‐related stressors can be mitigated via changes to angler behavior that reduce fight duration, handling, and air exposure. In some cases, stressors may significantly impact the ability of fish to engage in normal swimming behavior upon release. In these scenarios, it may be beneficial for anglers to assist recovery or retain fish until they are adequately recovered. In our study, we investigated the effectiveness of two assisted‐recovery devices at facilitating behavioral recovery in angled Rainbow Trout (Oncorhynchus mykiss): 1) retention in a flow box or 2) retention in a water‐filled cooler. Additionally, we compared the effects of assisted recovery in surface water (24 ºC – 27 ºC) or cool water pumped from the hypolimnion (17 ºC – 19 ºC). From July to mid‐September of 2020, 169 fish were angled from five stocked lakes at Kenauk Nature (Montebello, QC). Trout were air exposed for 30 s, 15 s, or not at all (0 s) and held in a flow box or a water filled cooler for 3 minutes, while fish in a control group were immediately released. Tri‐axial acceleration and temperature biologgers were temporarily fixed around the trunk of the fish with Velcro® to observe post‐release swimming behavior for 10 minutes. Trout that were held in assisted recovery devices regained equilibrium significantly quicker compared to those that were immediately released, and fish that were held in 17 ºC – 19 ºC water regained equilibrium the most rapidly. In fish that were air exposed for 30 s, individuals that were held in recovery devices exhibited greater swimming activity compared to those that were immediately released. Our study demonstrates that for Rainbow Trout, assisted recovery devices can reduce equilibrium impairment, especially when water in the recovery devices is significantly cooler than the relatively warm surface water temperature. Global water temperatures are expected to rise as a result of anthropogenic climate change, and best practices for angling should be adapted to reflect increased thermal stressors for many game fish species. Ensuring fish are vigorous upon release is imperative for reducing post‐release mortality through predation or thermal stress.
... The recovery of migratory adult fish was certainly facilitated with the recovery box, but it did not translate to higher levels of post-release survival assessed with biotelemetry, likely because dermal injuries enable opportunistic pathogens to take hold in freshwater more so than seawater ). Further tests with portable and inexpensive fish holding bags that were more suited to river fishing came to a similar conclusion (Donaldson et al. 2013;Raby et al. 2014); short-term holding suppressed the cortisol stress response, but unless the salmon was completely exhausted, there was little benefit in terms of post-release survival (Donaldson et al. 2013). Lastly, efforts to facilitate recovery by hand (just by holding fish into the flow) also seemed to generate minimal benefits except for the most exhausted individuals (Robinson et al. 2013(Robinson et al. , 2015. ...
... The recovery of migratory adult fish was certainly facilitated with the recovery box, but it did not translate to higher levels of post-release survival assessed with biotelemetry, likely because dermal injuries enable opportunistic pathogens to take hold in freshwater more so than seawater ). Further tests with portable and inexpensive fish holding bags that were more suited to river fishing came to a similar conclusion (Donaldson et al. 2013;Raby et al. 2014); short-term holding suppressed the cortisol stress response, but unless the salmon was completely exhausted, there was little benefit in terms of post-release survival (Donaldson et al. 2013). Lastly, efforts to facilitate recovery by hand (just by holding fish into the flow) also seemed to generate minimal benefits except for the most exhausted individuals (Robinson et al. 2013(Robinson et al. , 2015. ...
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Pacific salmon undertake iconic homeward migrations where they move from ocean feeding grounds to coastal rivers where they return to natal spawning sites. However, this migration is physiologically challenging as fish have to navigate past predators, nets, hooks, and dams while dealing with variable flows, warm water temperatures, and pathogens. These challenges often interact in synergistic ways that can sometimes lead to migration failure. The conservation physiology toolbox has led to new understanding of how salmon deal with different challenges with a goal of generating management-relevant science. Given the sensitivity of Pacific salmon to warm temperatures, much research has focused on identifying thermal thresholds. In addition, physiology has informed the development of methods for recovering fish that are exhausted from fisheries interactions and for enhancing passage success at fishways. These successes have arisen in part due to the extent to which we partnered with fisheries managers and other stakeholders to ensure that we were conducting relevant research.
... Slow swimming helped accelerate recovery of Rainbow Trout Oncorhynchus mykiss from anaerobiosis, so providing a gentle current may be helpful (Milligan et al. 2000). Specialized devices for holding fish and facilitating recovery have been developed for Pacific salmon Oncorhynchus spp. that consider their specific physiological needs (Farrell et al. 2001;Donaldson et al. 2013). ...
Each year, thousands of fishes are tagged with electronic devices to study their biology and inform fisheries management. Such research assumes that the process of capturing, tagging, and then holding fish to allow them to recover before release (i.e., the “tagging process”) does not alter the physiology, behavior, and survival of these fish. However, the fish can experience physiological challenges during the tagging process that may affect their behavior and survival. We have observed that the rationale used to establish protocols for holding durations and conditions of fish before and following surgery has received little attention. Here, we provide a perspective that: (1) provides an overview of the tagging process and its effects on the physiology, behavior, and survival of fish; (2) highlights the diverse holding conditions and durations used by researchers (that are often inadequately described and seem arbitrary); and (3) identifies key research needs. We conclude that decisions of whether, how, and for how long to hold tagged fish before release depend on diverse circumstances that need to be evaluated by researchers. We recommend that researchers explicitly report the details of how, when, where, and why tagged fish are held to facilitate protocols that benefit fish welfare, science, and management.
... In this study, only an air exposure of 420 s influenced reflex impairment score. A large body of research has previously demonstrated the effects of holding (Cooke et al. 2002;Donaldson et al. 2013;Chhor et al. 2022b), fish size (Loftus et al. 1988;McLean et al. 2020), fight time Blyth and Bower 2022), and air exposure (Gingerich et al. 2007;Donaldson et al. 2014;Logan et al. 2019;Chhor et al. 2022a) on reflex impairment. For example, brook trout > 328 mm with air exposure times >10 s exhibit higher reflex impairment measures (Brownscombe et al. 2022). ...
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We examined behaviour and physiology of lake trout (Salvelinus namaycush) following ice-angling. Fish were ice-angled and placed in a water-filled tub for 0.5, 4, and 6h to recover (n=19). Reflex impairment and physiological status were assessed repeatedly for every individual. Longer fight times lead to higher lactate and glucose, and lower extracellular pH 0.5h post-angling. Loss of orientation was the most common reflex impairment (84% of fish) 4h post-angling. Mortality (36.8%) was observed during the study; however, variation in handling, barotrauma, and issues with sampling may have confounded angling effects. To determine if barotrauma impacted impairment and mortality, lake trout at a later sampling date (n=29) were exposed to air for either 60, 120, 180, 240, 300, or 420s before assessment (3.4% mortality). For fish air exposed for 300s or more, 14% lost orientation during immediate assessment. Bloating occurred in 20% of fish air exposed for 60s. An air exposure duration of 420s significantly impaired reflexes. Recreationally caught lake trout show behavioural and physiological impairment with such impairments magnified by extended air exposure.
... Addressing physiological and behavioral metrics together can provide valuable insight into the relationship between biochemical and organismal stress responses as well as the potential impacts on population-level processes (Fefferman and Romero 2013;Cooke et al. 2016;Louison et al. 2017;Balasch and Tort 2019). Biologging and telemetry technologies have provided researchers with the tools necessary to monitor the fine-scale activity of wild animals in 2 of 21 their natural environments and to avoid the influences of chronic stress from confinement impacting normal behavior (Lowe and Kelley 2004;Donaldson et al. 2008Donaldson et al. , 2013Cooke et al. 2012Cooke et al. , 2016Brooks et al. 2019;McGarigal et al. 2020). ...
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Game fish populations in North America face increasing pressure from recreational anglers, yet sublethal effects from mandatory catch‐and‐release regulations remain unknown for many targeted species. In southern California, Kelp Bass Paralabrax clathratus populations have significantly declined in recent decades, prompting changes in management and increasing release rates. To assess acute effects of current fishing regulations, we collaborated with recreational anglers to evaluate short‐term, sublethal impacts of capture stress on Kelp Bass physiology and behavior. To evaluate the timeline and magnitude of physiological stress, blood samples were collected at time points (10–120 min) after angling and confinement and compared to control fish sampled in less than 3 min. Postrelease recovery was determined by comparing biomarker levels between control fish and recaptured fish that were rapidly sampled after a time at liberty ranging from 3 h to 186 d. Biomarker levels in fish recaptured multiple times were compared to previous samples to evaluate repetitive angling effects on physiological responses. Circulating cortisol, glucose, and lactate were elevated and steadily increased in the hour after capture, although angling duration and handling duration were not correlated with biomarker response. Fish size significantly affected fish stress, with larger fish experiencing less stress and rapid recovery within 24 h. Behavioral control fish, which ingested acoustic accelerometers hidden inside bait, exhibited strong diel activity that was reduced for 30 h in angled fish. Tracked individuals exhibited high individual variation in rate of movement and area use, with no noticeable postrelease impacts. Although this study found Kelp Bass to be resilient to angling stresses, evaluation of long‐term effects from catch and release is warranted. This fishery may also benefit from slot limit regulations, improved angler engagement programs, and education on best practices that minimize fish stress during catch and release.
... Interest is growing among movement ecologists to engage with social scientists and social research to better understand the implications of their research to society, promote evidence-based decisions and practices, as well as engage in a more holistic approach to a problem or research question. For example, Donaldson et al. (2013) combined biotelemetry, physiological assessments, and social surveys to illustrate effectiveness of and positive attitudes towards 'recovery bags' as means to facilitate recovery of sockeye salmon after recreational angling capture. Similarly, a study by Raby et al. (2014) combined biotelemetry and social surveys to explore solutions for bycatch mortality of an endangered population of coho salmon caught in a Indigenous beach seine fishery in British Columbia. ...
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methods used, as well as the outcome or objectives targeted for each method. In addition to summarizing the use of complementary methods and their outcomes, we discuss how they supplement acoustic telemetry and other tracking approaches. Our review shows that using additional methods to support telem-etry data helps expand the breadth of research questions that can be addressed regarding the complex and assorted factors influencing movement patterns. Doing so enables greater value in movement ecology research and adjacent fields such as population dynamics, physiology, trophic ecology, reproduction, and health and survival, to underpin management decisions. This review serves as a primer and guide for bolstering data collection and multidisciplinary Abstract Tracking the movements of aquatic animals is a primary means of understanding movement ecology and interactions with human activities such as fisheries. Despite the diverse spatiotemporal scales that various underwater tracking tools (e.g., acoustic, satellite, PIT, radio, archival telemetry) enable, there are still limitations associated with their application and ability to address diverse research questions. In many cases, supplementary methods are used to complement tracking approaches either to overcome such limitations or to optimize the data that can be collected in a study. In this review, we synthesize relevant literature between 2010 and 2019 to evaluate the different types of complementary methods used with one of the main approaches for tracking fishes-acoustic telemetry. We categorize broad and specific
... Despite many cogent arguments available in the scientific literature on the value of using mechanistic physiological measures for determining cause-effect relationships (Carey, 2005;Pörtner and Peck, 2010;Ellis et al., 2011;Blaustein et al., 2012;Seebacher and Franklin, 2012), we believe explicit success stories (e.g. Tracy et al., 2006;Cooke et al., 2012;Donaldson et al., 2013;Madliger et al., 2016;Madliger et al. 2021) will speak more loudly than theoretical arguments. ...
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Conservation physiology represents a recently emerging arm of conservation science that applies physiological tools and techniques to understand and solve conservation issues. While a multi-disciplinary toolbox can only help to address the global biodiversity crisis, any field can face challenges while becoming established, particularly highly applied disciplines that require multi-stakeholder involvement. Gaining first-hand knowledge of the challenges that conservation physiologists are facing can help characterize the current state of the field and build a better foundation for determining how it can grow. Through an online survey of 468 scientists working at the intersection of physiology and conservation, we aimed to identify characteristics of those engaging in conservation physiology research (e.g. demographics, primary taxa of study), gauge conservation physiology’s role in contributing to on-the-ground conservation action, identify the perceived barriers to achieving success and determine how difficult any identified barriers are to overcome. Despite all participants having experience combining physiology and conservation, only one-third considered themselves to be ‘conservation physiologists’. Moreover, there was a general perception that conservation physiology does not yet regularly lead to tangible conservation success. Respondents identified the recent conceptualization of the field and the broader issue of adequately translating science into management action as the primary reasons for these deficits. Other significant barriers that respondents have faced when integrating physiology and conservation science included a lack of funding, logistical constraints (e.g. sample sizes, obtaining permits) and a lack of physiological baseline data (i.e. reference ranges of a physiological metric’s ‘normal’ or pre-environmental change levels). We identified 12 actions based on suggestions of survey participants that we anticipate will help deconstruct the barriers and continue to develop a narrative of physiology that is relevant to conservation science, policy and practice.
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Catch-and-release (C&R) angling is a conservation-oriented practice intended to reduce the impact recreational angling has on fish populations. Even though most recreationally angled fish are released, little is known about how C&R angling impacts fish at the cellular or tissue level. As the first to explore the impacts of C&R angling on mRNA abundances, our study aimed to identify how the stress of angling influenced metabolism, acid–base regulation and cellular stress in the gills of lake trout (Salvelinus namaycush). Because gills are responsible for metabolic gas exchange, are crucial sites of acid–base homeostasis and respond to stressors quickly, we hypothesized that the relative mRNA abundance of genes related to these three physiological processes would be altered after angling. We took gill samples of live lake trout at 0, 2 or 48 h after fish were angled by rod and reel, and then used quantitative PCR (qPCR) to measure the relative abundance of nine candidate mRNA transcripts. Heat shock protein 70 (hsp70) mRNA levels significantly increased over 5-fold 2 h after angling, indicating a potential activation of a cytoprotective response. However, contrary to our hypothesis, we observed no change in the relative mRNA abundance of genes related to metabolism or acid–base regulation in response to C&R angling within a 48-h period. As C&R angling can negatively impact fish populations, further use of transcript-level studies will allow us to understand the impact C&R has on specific tissues and improve our knowledge of how C&R influences overall fish health.
The cardiorespiratory system distributes oxygen and other factors (nutrients, wastes, hormones etc.) around the body and thus plays a central role in mediating many physiological processes such as digestion, locomotion, and reproduction. Building from a rich body of foundational research, cardiorespiratory physiology techniques are now being used for applied, conservation purposes. These techniques can evaluate performance at the whole animal, organ, or cellular levels. At the whole animal level, metabolism and energetic capacities are routinely measured. Aerobic scope (the maximum energetic capacity of a fish beyond maintenance; absolute aerobic scope = maximum metabolic rate − standard metabolic rate) is used to identify optimal conditions for fish. At the level of the heart, heart rate biologging and biotechnology techniques enable researchers to monitor performance in free-ranging fish, while Arrhenius breakpoint tests can measure the optimal and upper thermal limits for the heart. At the cellular level, blood sampling is an easy and effective way to gain a wealth of information about the physiological status of the fish. Several case studies are presented to illustrate how cardiorespiratory physiology techniques have been effectively put into practice (Pacific salmon conservation, shark fisheries-induced mortality, pelagic fishes responding to oil). We conclude with some recommendations to continue moving the field forward and advance fish conservation.
Fishery discard survival depends on multiple conditions; caution is essential when survival study outputs are employed to support management decisions. The study presents a stepwise procedure, devised to estimate discard survival, that accounts for the variability characterizing commercial fishing practices. The procedure was applied to the first survival study performed onboard rapido trawlers targeting Solea solea in the Mediterranean Sea. Undersized specimens collected during sorting were assessed for vitality; some were retained for captive observation. The main drivers affecting discard survival at the time of catch sorting (immediate survival) were identified and used to outline four different operational conditions set (scenarios). Immediate survival in each scenario was subsequently modified by applying a hazard coefficient of survival after 5 days of captive observation in relation to each vitality class, thus obtaining relative survival estimates following discarding. Temperature and air exposure duration were found to exert a major effect on survival, with catch weight and seabed type being additional important factors. The relative survival rate showed an aggregate value of 22.9% (10.5-33.4%). Scenario approach can enhance our understanding of the stressors influencing discard survival. The outcomes are discussed to explore the potential applications of the procedure to the identification of mitigation strategies.
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Approximately 200 km from the mouth of the Fraser River, British Columbia, Canada, adult sockeye salmon Oncorhynchus nerka, were gastrically implanted with radio transmitters without anaesthetic. Subsets of the transmitter implanted fish were also biopsied which included drawing blood from the caudal peduncle (3 ml), removal of gill tissue (0·03 g) and quantification of energetic status using a microwave fat meter. Several experiments were used to test the hypothesis that the biopsy had a negligible effect on the subsequent survival and migratory behaviour of transmitter implanted fish. In the first experiment, no difference was found in the survival (both 100%) or tag retention (both 100%) between the two treatment groups (transmitter implanted with and without biopsy) when fish were held in pens for 24 h in the marine environment. Similarly, in other experiments where fish were released to the ocean to resume their migratory journey, no statistical differences were found in the travel times of fish in the two treatment groups, or in the proportion of fish that passed in‐river telemetry checkpoints. These results indicated that the handling and biopsy methods produced similar levels of mortality and tag retention as the telemetry treatment alone and that any changes in behaviour between the two treatment groups did not adversely affect migration time. Based upon the evidence provided from the biotelemetry of >300 adult sockeye salmon, it was felt that this general type of approach could be applicable to other fish species.
Widely renown for his work and publications on qualitative and mixed methods research, John W. Creswell recently published the third edition of Research Design: Qualitative, Quantitative, and Mixed Methods Approaches. The book is structured around 2 parts and 10 chapters that mirror the main stages of development of a research project. Although a plethora of books covering research design exist, this book is especially interesting because it very simply and clearly discusses the subject, mainly bringing useful comparisons between qualitative, quantitative and mixed methods approaches that aid the researcher in planning a research endeavour. While Creswell's book covers the essential questions and concerns enabling the operation-alization of a research project, it furthermore addresses issues that, to our knowledge, having read many books on the subject, are scarcely found elsewhere. These issues are presented in the first part of the book under the heading Preliminary Considerations and include an overview of the main uses and modes of presentation of the review of the literature in a research protocol or report, as well as the use of theory. As an example, in Chapter 3 entitled Use of Theory, Creswell explicitly discusses the roles of theory that differ according to the types of research design (e.g. theory generation, theory verification), acknowledging that there are many possible variations within each research approach. Hence, this expanded and restructured edition of John Creswell's Research Design is a user-friendly and rich scientific resource, and appears as a must for any researcher wanting to tackle the indispensable subject of research design by contrasting qualitative, quantitative, and mixed methods approaches.
To reduce mortality in the by-catch of commercial salmon fisheries, techniques are being explored to revive fish before live release and improve survival. By measuring blood and muscle variables, we demonstrated that capture of coho salmon (Oncorhynchus kisutch) by commercial trolling methods resulted in severe exhaustion and stress, e.g., muscle lactate reached 46.1 mmol·kg-1 while muscle phosphocreatine (PCr) decreased to 6.1 mmol·kg-1. Nevertheless, coho salmon recovered rapidly by swimming in a cage alongside the vessel while fishing activity continued. In particu- lar, there were significant increases in muscle glycogen and PCr levels, and a decrease in muscle lactate after two hours. Notably, and in contrast to when exhausted fish are held stationary during recovery, plasma lactate remained low (
Successful application of fish-revival techniques in commercial fishing prior to release of nontarget species requires clear evidence that recovery devices do indeed improve physiological status and minimize postcapture delayed mortality. This study provides such evidence for a newly designed recovery box (Fraser box) that assisted gill ventila - tion. Immediately after capture by gillnet, adult coho salmon (Oncorhynchus kisutch) were in a state of severe meta- bolic exhaustion and stress, based on a comprehensive analysis of plasma and muscle tissue. However, when placed in a Fraser recovery box for 1-2 h, both lethargic and vigorous fish showed significant metabolic recovery and their abil - ity to swim was also quickly restored. An emphatic demonstration of the benefit of the Fraser box was the successful revival of >90% of fish that appeared dead at capture. Furthermore, postcapture delayed mortality was only 2.3% after a 24-h observation period. Therefore, in the context of commercial salmon gillnet fishing, revival of nontarget coho salmon in a Fraser box, in combination with a soak time (total time the gillnet is in the water) 70 min and careful fish handling to minimize physical trauma, could improve physiological status, restore swimming ability, and markedly reduce postcapture delayed mortality. Farrell et al.
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.