Directory UMM :Data Elmu:jurnal:A:Aquaculture:Vol185.Issue1-2.May2000:

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Ž .

Aquaculture 185 2000 159–173

www.elsevier.nlrlocateraqua-online

The effect of PIT tags on growth and physiology of

age-0 cultured Eurasian perch Perca flu

Õ

iatilis of

variable size

Etienne Baras

a,)

_{, Christelle Malbrouck}

, Marc Houbart

,

Patrick Kestemont

, Charles Melard

´

UniÕersity of Liege, Laboratory of Fish Demography and Aquaculture, 10 Chemin de la Justice, B-4500`

Tihange, Belgium b

( )

Facultes Uni´ Õersitaires N.D. de la Paix, Unite de Recherches en Biologie des Organismes URBO , 61 Rue´

de Bruxelles, B-5000 Namur, Belgium Accepted 20 October 1999

Abstract

For many biological reasons, it is often necessary to tag and monitor fish from a very early age. However, tagging can adversely affect fish, especially for high tag to body weight ratios. To

Ž .

determine the minimum size for passive integrated transponders PIT tagging in juvenile perch

Ž Perca fluÕiatilis, surgical implantation was evaluated in fish ranging from 1.67 to 10.62 g 55–96

mm FL . The survival, gonadal development, and capacity of tagged perch to store abdominal fat was affected neither by the tagging procedure, tag presence, nor tag to body weight ratio. Four months after tagging, no tag had caused internal damage or had been expelled, despite about 95% of them becoming encapsulated by host tissues. Negative effects from tagging were restricted to slower healing rates, and depressed growth of fish with high tag to body weight ratios during the first post-tagging days, which was compensated for by catch-up growth within less than 2 weeks. Surgical PIT tagging can be confidently applied to perch weighing less than 2 g, but the collection of biological data should be delayed by about 2 weeks after tagging. X-ray photographs revealed

Ž . Ž .

variable orientations of tags 95% CI: 268 and slight ca. 48 changes of orientation over time. These discrepancies may affect the probability that the tag is detected by automatic data entry

stations, and should be compensated for by using smaller antennas F87% of maximal antenna

)_{Corresponding author. Tel.:}_q_{32-85-27-41-56; fax:}_q_{32-85-23-05-92.}

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E-mail address: [email protected] E. Baras .

Ž .

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1. Introduction

It is important that fish be individually identified because performance varies

substantially among individuals of different or the same size e.g., Jobling et al. 1989;

Alanara and Brannas 1993; McCarthy et al. 1994 . This should ideally be done from the

¨ ¨

youngest possible age and extend over long periods of time. Passive integrated

transpon-Ž .

ders PITs; Prentice et al. 1984, 1990a are among the best candidates for tagging small

Ž .

fish. These are low weight F100 mg tags, with unlimited functional life and billions of individual codes, and can thus be applied to large samples of fish. The use of data entry stations allows the automatic detection of PIT tagged fish passage or presence at

Ž . Ž

close range within 20 cm of detecting antennas Prentice et al. 1990b,c; Brannas and

¨

Alanara 1993; Brannas et al. 1994; Armstrong et al. 1996 .

¨ ¨

PIT tags have been applied mainly to large fish in husbandry management e.g.,

Jenkins and Smith, 1990 . The tag is inserted into the dorsal musculature of broodfish, represents a tiny proportion of their body weight, and has no marked effect on their physiology. Few studies have documented the feasibility of implanting PIT tags into the

body cavity of small juveniles, and most of these concerned salmonids Prentice et al.,

1990a; Brannas and Alanara, 1993; Peterson et al., 1994 . Behavioural and physiological

¨

¨ ¨

reactions to identical tagging procedures may differ substantially between species

Ž_{Winter, 1983; Summerfelt and Smith, 1990; Baras et al., in press , and feasibility}.

studies on tag acceptance are strongly encouraged when no detailed data are available on the species of interest, both for ethical considerations and validation of results. This

Ž .

becomes crucial when using high tag ratios tag weightrfish weight , close to or above

the mean adjustment capacity of the swimbladder in teleost fish ca. 1.75%, Alexander,

. Ž

1966 , as most tagging biases were reported in these circumstances Greenstreet and

Morgan, 1989; Summerfelt and Smith, 1990; Baras et al., in press . More recent studies with carefully tailored procedures suggest that higher tag ratios can be used without

causing substantial biases in the long run Claireaux and Lefranc

¸

ois, 1998; Martinelli et

al., 1998; Baras et al., 1999 .

This paper is a component of research programmes on the biology of cultured juveniles of the Eurasian perch Perca fluÕiatilis, which rely on monitoring the activity of PIT tagged individuals through the use of automatic data entry stations. To evaluate the adequacy of the tagging technique and to determine the minimum size at which perch can be tagged successfully, the intensity and duration of the perturbation caused by the tagging procedure and tag presence were measured based on tag retention, survival, growth, healing progress and physiology of juvenile perch of different body

Ž .

weights 1.67–10.62 g, 55–96 mm fork length . As the detection of PIT tags is governed by the laws of inductive coupling, the orientations of implanted tags and their stability over time were also examined to test whether all tagged fish would have the same chances of being detected by automatic stations.

2. Material and methods

2.1. Fish origin and experimental infrastructure

The fish used in the experiment were hatchery reared age-0 perch obtained from natural spawning by captive breeders in the rearing facilities of the Tihange Aquaculture

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E. Baras et al.rAquaculture 185 2000 159–173 161

Ž .

Station of the University of Liege Belgium . Larvae and young juveniles were reared

`

Ž . 2 _Ž 3_.

over 6 weeks at constant temperature 22"18C in 10 m 4 m outdoor flow through

tanks, then were transferred into an indoor recirculating circuit 250-l aquarium,

12L:12D . Water temperature was maintained at 22"18C and monitored by a data

Ž .

logger TidBit, ONSET Comp. . Oxygen concentration in the aquarium was measured once a day and was never -5.5 mg ly1_{. Water was supplied from well water, and the} infrastructure was deemed to be pathogen-free, except when fish from outdoors facilities were transferred for establishing experimental groups. The first experiment was con-ducted in a non-pathogen-free environment to test for the effect of pathogens on the survival of tagged fish, and whether survival and retention were affected by the tagging protocol.

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2.2. Comparison between tagging protocols Experiment 1

Three protocols were assayed on groups of 30 fish each 2.78–8.54 g, 65–90 mm

. Ž

fork length , using alcohol sterilised TROVAN transponders model ID100, 11=2.2

mm in diameter, 100 mg in the air, 58 mg in the water . In all three protocols, juvenile

Ž y1_.

perch were anaesthetised with tricaine methanesulfonate 90 mg l and placed ventral side up in a support made of wet paper. In the first group, the tag was injected into the body cavity, using a standard 12-gauge needle injector passed through the midventral body wall. In the second and third groups, the tag was inserted through a 3-mm long incision made with a scalpel on the linea alba, ca. 2–3 mm anterior to the papilla. In the second group, the incision was left open, as it normally is, following the injection of the tag with a syringe. In the third group, it was closed with a single stitch of polyamide

Ž .

monofilament suture material 0.7 Dec fixed to a 12-mm curved cutting needle. On average, the surgical implantation was completed within 60 s, and suturing required further 60–80 s. The syringe injection procedure never took more than 30 s.

The 90 tagged fish were reared over 4 weeks in the same aquarium, together with 30

Ž .

control handled but not tagged fish of similar body weight, so control and tagged fish

were exposed to the same pathogens. Formulated feeds 50% protein, 11% lipid

contents were distributed during daytime by an automatic feeder, starting ca. 1 h after

Ž .

illumination. The daily food ration DFR, % BWm was close to the optimum ration at

y0 .24 _{Ž .} _Ž

22–238C, and was 3.30 Wm , where Wm is the mean body weight g of fish Melard

´

et al., 1996 . The aquarium was searched twice a day for dead fish and lost tags. Fish were examined once a week to measure individual growth rates; specific growth rates

Ž . y1 _w _x_Ž _.y1

SGR , % d s100= ln W2yln W1 t2yt2 , where W and W2 1 were the body weights at times t and t , respectively. Upon the first examination and weighing, the₂ ₁ stitch was removed to avoid any detrimental long term effect inherent to the presence of

a transcutaneous foreign body Knights and Lasee, 1996; Thoreau and Baras, 1997;

Baras et al., in press .

Ž .

Prentice et al. 1990a provided evidence for a good correspondence between visual observation and histological examination when evaluating the healing progress in PIT tagged salmonids. The incision was considered as completely healed when the external layers of the body wall had closed up, and the perch was regarded as having recovered

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its physical integrity when the incision was covered by regenerated scales. The mean healing time for each treatment was deduced from the distribution frequency of healed fish at each inspection.

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2.3. Determination of minimum fish size for pit tagging Experiment 2

Approximately 2000 juvenile perch were acclimatized for 10 days to the experimental infrastructure and no pathology was observed prior to tagging. Two hundred and twelve

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fish 1.67–10.62 g, 55–96 mm fork length were tagged with transponders, using

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surgical implantation and suturing see justification in Table 1 . No fish smaller than 55

Ž .

mm was tagged because the length of its body cavity excluding the pericardial cavity was similar to the length of the tag. Analyses were made on eight weight classes,

corresponding to mean tag ratios in the water from 0.75% to 2.62% corresponding

ratios in the air from 1.29% to 4.52%; Table 2 .

Table 1

Comparison of SGR, survival, tag expulsion, and healing progress of PIT tagged age-0 perch P. fluÕiatilis,

Ž y1 _.

depending on the tagging protocol 30 fish in each group; 250-l aquarium;G5.5 mg l O ; 22–232 8C

Ž .

For each line of the table, the categories sharing at least one common superscript a, b, c are not significantly

different, whereas the other comparisons differ at P-0.05 Fischer PLSD comparison of means for growth

. Ž .

and body weight, contingency tables for tag expulsion, mortality and healing progress . ‘‘ 3D 5’’ in the expelled tags lines means that tags were expelled by five fish, of which three eventually died.

Syringe Surgery, Surgery, Control

injector no suture suture

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Body weight BW, mean"SD, g

a a a a

d 0 4.78"0.97 5.06"1.37 5.01"1.08 4.88"1.47

a a a a

d 42 7.30"1.78 7.58"2.63 7.05"1.98 7.88"2.77 y1

( )

SGR mean"SD, % BW d

ab ab a b

dd 1–7 1.60"0.85 1.58"1.09 1.30"1.34 2.00"1.39

a a a a

dd 8–14 1.38"0.72 1.52"0.87 1.66"0.79 1.67"0.72

a a a a

dd 15–21 1.66"0.60 1.90"0.76 1.68"0.56 1.92"0.49

a a a a

dd 22–28 1.20"0.66 1.13"0.61 1.27"0.46 1.39"0.66

( )

Dead fish running sum

a ab a b

d 7 8 3 7 0

a ab ab b

d 14 12 6 7 3

a ab ab b

d 21 12 7 7 3

a ab ab b

d 28 12 7 7 3

a ab b a

Initial body weight of dead fish 4.43"0.80 4.95"0.79 5.62"1.00 3.56"1.73

Žmean"SD, g.

( )

Expelled tags running sum

a a b

Ž .

d 7 3D 5 4 0 –

a a b

Ž .

d 14 6D 7 6 0 –

a a b

d 21 7 6 0 –

a a b

d 28 7 6 0 –

a a b

Ž .

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()

Baras

al.

Aquaculture

185

2000

159

–

173

163

Table 2

Comparisons between SGR, survival and healing progress of juvenile P. fluÕiatilis tagged with surgically implanted PIT tags, depending on the initial body weight

Ž_{250-l aquarium;}_{G5.5 mg l}y1 _{O ; 22–23}₈_{C except from days 22 to 32: 20–21}₈_C_. 2

Tag retention was 100%. Tag ratio stands for tag weightrfish weight. Growth rates were independent of tag ratio on any of the four controls between days 43 and 126, and are not illustrated separately.

Ž .

For each line of the table, the categories sharing at least one common superscript a, b, c are not significantly different, whereas the other comparisons differ at

Ž .

P-0.05 Fischer PLSD comparison of means for growth and body weight, contingency tables for mortality and healing progress .

Ž .

Weight class g -2.5 2.5–3.0 3.0–3.5 3.5–4.0 4.0–4.5 4.5–5.5 5.5–6.5 G6.5

( )

Mean tag ratio % BW

In air 4.52 3.65 3.09 2.69 2.35 1.97 1.66 1.29

In water 2.62 2.12 1.80 1.56 1.37 1.15 0.97 0.75

Initial numbers 34 29 34 31 27 21 17 19

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Dead fish running sum

a a a a a a a a

d 42 1 0 0 1 1 1 1 1

b a a a a a a a

d 126 11 2 3 4 3 1 1 1

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Sex ratio F:M

d 0 22:12 12:17 17:17 12:19 14:13 12:9 10:7 12:7

d 126 18:5 11:16 15:16 10:17 13:11 12:8 10:6 11:7

( ) ( )

Body weight BW mean"SD, g

d 0 2.21"0.24 2.74"0.16 3.24"0.12 3.72"0.17 4.26"0.14 5.08"0.26 6.03"0.23 7.73"1.03 d 42 3.95"0.65 5.07"1.13 5.76"1.22 6.22"0.99 7.08"0.77 8.47"1.35 9.74"1.60 11.83"2.83 d 126 13.53"4.07 17.22"6.42 19.43"5.65 21.59"7.25 25.89"8.08 27.60"7.26 34.39"11.41 44.40"14.20

( ) ( )

SGR % BW d mean"SD

a a a a a b b b

dd 1–11 1.00"1.07 1.17"0.66 1.10"0.76 1.12"0.86 1.00"0.67 1.62"0.87 1.72"0.64 1.58"0.46

a a a ab b bc c c

dd 11–21 1.95"0.80 1.82"0.68 1.81"0.51 1.58"0.67 1.42"0.53 1.31"0.44 0.98"0.62 1.06"0.62

a a a a a a a a

dd 22–32 0.91"0.60 1.04"0.45 1.00"0.54 0.97"0.44 1.06"0.31 0.91"0.35 1.05"0.38 1.15"0.35

a a a a a a a a

dd 33–42 2.36"1.95 1.99"1.58 1.88"0.77 1.69"0.75 1.88"0.37 1.70"0.48 1.64"0.51 1.93"0.39

a a a a a a a a

dd 43–126 1.48"0.21 1.50"0.29 1.50"0.32 1.51"0.37 1.60"0.32 1.49"0.55 1.55"0.38 1.66"0.14

b a a a a a a a

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Perch were reared over 126 days in groups initially three groups of 344 fish each, rearranged on day 43 into nine groups of 114–115 each, containing fish of all weight classes, at a ratio of ca. one tagged to three untagged fish. Food distribution, search for dead fish or expelled tags, assessment of healing progress and growth were as above,

except for the periodicity of the assessments twice every 3 weeks until day 42, then

once every 2 weeks .

The remote detection of transponders relies on inductive coupling, and is dependent on the orientations of the detecting loop and tag coil. Maximum coupling is obtained when the tag crosses perpendicular to the plane of the loop, and other angles cause a reduction in detection range, which is inversely proportional to the cosine of this angle with the ideal trajectory. Tags that are misplaced at the time of tagging or become disorientated during fish growth, may compromise coupling, reduce the detection range

Ž w x.

and the probability that the fish be detected i.e., reductions1ycos angular deviation . X-ray photographs of all tagged fish were made under anaesthesia on days 73, 94 and

Ž .

115 using an X-ray TR 80r20 Todd Research, UK and films Kodak X-OMAT MA, developed with Fuji Film FPM 100 A. Tilt angles to the sagittal axis of the body were measured to the nearest degree, assuming that this axis was the ideal trajectory for a fish crossing perpendicular to the antenna. Associated risks of detection failure were calculated as above. Photographs were used to determine the positions and migrations of the tags in the body cavity, using five classes of horizontal and vertical coordinates.

At the end of the experiment, all fish were dissected, and examined visually for gross

Ž .

morphological effects from surgery e.g., muscle necrosis, erythema and host tissue

Ž .

response to the tag e.g., embedded in adipose tissue, encapsulation . In all tagged fish and in a sample of 50 control fish, the abdominal adipose tissue was extracted with

Ž .

forceps and weighed. The gonado-somatic index GSI was measured and the sex of all

fish was determined from visual examination of gonads single ovary in female perch

and two testes in male perch; Mallison et al., 1986; Craig, 1987 . The aceto-carmin

Ž .

squash technique Guerrero and Shelton, 1974 was also used on randomly sampled fish to validate the visual assessment of their sex.

2.4. Statistical analyses

Contingency analyses were used to compare fish survival, tag retention rates and healing progress in both experiments, and to test for the effect of initial body weight at tagging on host tissue reaction and tag positioning in Experiment 2. Analyses of

Ž .

variance one-way ANOVA and Fischer PLSD comparisons of means were used to compare the orientations of tags, the body weights and growth rates of fish. The growth rates of controls were calculated from the ordinated distributions of their body weights at the beginning and end of each rearing period. This calculation relied on the assumption of the primacy of early size differences, which is not an invalid assumption

Ž .

for short term experiments see Baras, 1999 . Factorial ANOVA was used to test for differences between the GSI and proportion of perivisceral fat, depending on fish sex and weight class. Student’s t-test and simple regressions tests were also used when appropriate. Null hypotheses were rejected at P-0.05.

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E. Baras et al.rAquaculture 185 2000 159–173 165 3. Results

3.1. Comparison between tagging protocols

At the end of the 28-day rearing period in a non-pathogen-free environment, fish

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mortality amounted up to 24.2% Table 1 . The mortality was lower in controls than in

Ž .

tagged perch, especially in those tagged with syringe injectors 40% . Tag retention by sutured fish was 100%, whereas it was F80% in the two other groups. Suturing also favoured healing: it was about 1 week faster than in the other groups. Sutured fish grew at a slower rate than controls over the first week, whereas other tagged fish were less affected. From the second week onwards, after the stitch was removed, the growth rate of sutured fish was similar to those in other groups. Sutured fish ended up with the smallest body weight of all groups, but essentially because fish dying in other groups tended to be the smallest individuals. These preliminary results showed that surgical implantation and suturing was more favourable than other protocols to tag perch in an environment with pathogens.

3.2. Determination of minimum fish size for pit tagging

Over the first 6 rearing weeks, the mortality of tagged perch was low six of 212

. Ž 2 _.

fish , similar to that of controls 28 of 820 fish; x s0.12; Ps0.7274 and

indepen-Ž .

dent of the initial tag ratio Table 2 . After the fish had been regrouped into nine groups,

Ž y1_.

mortality was slightly higher than before 0.95% vs. 0.77‰ d , but did not differ

significantly between control and tagged fish 47 of 630 and 20 of 206 fish, respectively;

2 _.

x s1.07; Ps0.3020 . There was a higher proportion of males among the dead tagged

fish than among the survivors, but the same was observed among controls 15 M:11 F

2 _.

and 29 M:18 F, respectively; x s0.02; Ps0.8876 .

Tagging and tag ratio did not affect the development of gonads, which was only

dependent on fish sex ANOVA: Ps0.2697 and P-0.0001 for initial body weight

and sex, respectively; Fig. 1a . The mean GSIs of tagged females and males were 0.51%

and 3.10%, and were similar to those of controls 0.56% and 3.05%, respectively;

unpaired t-tests, P)0.95 . The proportion of perivisceral fat in tagged fish on day 126

Ž .

was also similar to that in controls 2.97% vs. 3.04%; unpaired t-test, Ps0.8948 , but

Ž .

differed significantly with respect to fish size and initial tag ratio ANOVA: Ps0.0007 . Large males and females accumulated more than 4.0–5.0% of fatty reserves, whereas

Ž .

small fish rarely accumulated more than 3.0% Fig. 1b .

There was no long term detrimental effect of tagging and transponder presence in the body cavity on the growth performance of female and male perch, as tagged fish

outweighed slightly control fish at the end of the experiment 24.52 vs. 23.62 g and 23.21 vs. 22.43 g, for females and males, respectively; ANOVA: Ps0.1474 and

Ps0.2680 for fish sex and treatment, respectively . Fish with tag ratios in the water

higher than 1.25% grew first at a slower rate than controls or larger tagged fish Table

. Ž .

2 . However, this detrimental effect was restricted to a short period only ca. 11 days , then was compensated by much higher growth rates over the following period. During the rest of the study, growth was no longer dependent on the initial tag ratio, even in the weight classes that still had a tag ratio higher than 1.25% at that time. Tag ratio affected healing rate too, as small fish took significantly longer to heal their incisions than larger

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Ž . Ž .

Fig. 1. Variation of gonado-somatic index a and storage of perivisceral fat b by PIT tagged age-0 perch 126 days after tagging, depending on their body weight at tagging. Error bars stand for the standard deviation of

the mean in each weight class. Open bars: tagged females; closed bars: tagged males; dashed bars: control ctl,

handled but untagged females and males. In each graph, bars sharing at least one common superscript are not

significantly different, whereas the other comparisons differ at P-0.05 Fischer PLSD comparison of

means .

Ž .

individuals 15.8 vs. -12 days, in fish -2.5 g and )4.5 g, respectively . The covering of incision by regenerated scales also took longer in smaller fish, but differences vanished after day 33.

No perch expelled its transponder over the 126-day study period. X-ray photographs

showed most tags near the abdominal musculature and none higher than midgut Fig.

. Ž

2a . Tags showed no vertical migration but moved slightly anterior as fish grew Fig.

2b . Few tags were found close to the anterior or posterior edge of the body cavity

Ž7.7%, 4.8% and 5.3%, on days 73, 94 and 115, respectively . On average, the tags.

Ž .

deviated from the sagittal axis of the fish by less than 108 Fig. 2c , causing a reduction of coupling of ca. 1%. However, angles as high asy188andq408were observed, and

Ž .

the 95% confidence intervals of distributions ranged over ca. 268 10% reduction . The

deviation diminished slightly over time, as tags changed their orientation Figs. 2d and

3 . Changes of orientation of individual tags at 3-week intervals were less than 48 on average, and rarely cumulated over time. Neither the weight of fish at tagging nor the longitudinal position of the tag influenced its orientation and stability over time

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( )

E. Baras et al.rAquaculture 185 2000 159–173 167

Ž . Ž . Ž .

Fig. 2. Horizontal a , vertical positions b , and orientations c of PIT tags in the body cavity of age-0 perch, j days after tagging. Negative and positive orientations refer to tags heading ventral and dorsal, respectively.

w Ž .x

The reductions of detection range are calculated as 1ycos angular deviation , assuming that fish crosses

Ž .

perpendicular to the plane of the detecting antenna. Changes of orientations over time d are calculated for individual tags.

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Fig. 3. Illustration of the variable fate of PIT tags in the body cavity of perch. Plates a and b illustrate the same individual 73 and 115 days after tagging respectively and show a strong deviation of the PIT tag axis over time. Plates c and d illustrate another individual on the same dates, but with no deviation of PIT tag axis over time.

Ž_P)0.10 . Tags near midgut showed significantly P. Ž -0.0001 stronger deviations and. Ž

changes over time than those located near the abdominal body wall mean deviations of

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( )

E. Baras et al.rAquaculture 185 2000 159–173 169 Dissection on day 126 revealed no muscle necrosis, erythema, infection nor damage

Ž .

to internal organs. Most tags had become embedded in the adipose tissue 21.7% , or

Ž .

encapsulated into a fibrous capsule inside the adipose tissue 60.3% . Capsules adhered

Ž . Ž .

to the parietal 7.4% or visceral peritoneum 4.8% , but never to the intestine. The

Ž .

remaining tags 5.8% were free in the body cavity of individuals with less adipose

Ž 2 tissue than others. The host tissue response to the tag was independent of fish sex x ,

. Ž 2 _.

Ps0.7930 and was unaffected by the tag ratio x , Ps0.4851 .

4. Discussion

Surgery was adequate for PIT tagging juvenile perch, as the mortality of sutured tagged fish did not differ from that of controls, and was low compared to standards in

Ž .

perch culture Grignard et al., 1996b . Syringe injectors were less adequate than surgery techniques in an environment with fish pathogens, and this corroborated recent results in

another warmwater Percomorph, the Nile tilapia Oreochromis niloticus Baras et al.,

. Ž .

1999 . Prentice et al. 1990a reported that injectors did not compromise the survival of salmonids, even in waters containing pathogens. Compared to salmonids, perch in this study were reared at higher temperatures, which are known to favour microbial outbreak. Cultured perch are sensitive to numerous pathogens, and quite prone to

Ž .

develop pathologies in temperate or warm waters Grignard et al., 1996a,b . Open incisions increased the risk of microbial outbreak whereas sutured incisions did not. Suturing permitted a more rapid repair of the epidermis, which is critical for maintaining

Ž .

osmotic balance Anderson and Roberts, 1975 but the presence of the stitch compro-mised the growth of perch. This is a further example to the potential detrimental effect

of transcutaneous foreign bodies reported previously by several authors Roberts et al., 1973; Baras, 1992; Collins et al., 1994; Thoreau and Baras, 1997; Baras and Jeandrain,

1998 , and indicates that the stitch should be removed as soon as the fish has healed its incision. Considering the risks of microbial outbreak, the use of antibiotic powders

Ž_{terramycin, oxytetracycline, penicillin G, etc. that are injected into the caudal pedun-}.

cle, body cavity or applied as a mudpack over the incision, may be worth considering for PIT tagging perch.

On average, tagged perch healed their incision within 12–13 days at 22–238C. This is

Ž .

slower than juveniles of tropical species 7–10 days; Baras et al., 1999, in press ,

slightly faster than juveniles of cold-water species ca. 14 days; Moore et al., 1990;

Prentice et al., 1990a and about twice as fast as adults of temperate species healing an

incision of a similar relative length 4–6 weeks; Pedersen and Andersen, 1985; Baras,

1992; Knights and Lasee, 1996 . The dynamics of wound healing, which involves tissue resorption then reconstitution, is a function of the main variables that influence fish

growth, including species, life stage, metabolism and temperature Anderson and

Roberts, 1975; Marty and Summerfelt, 1990; Baras et al., in press . Small perch, which have higher growth potentialities than larger individuals, were expected to heal their incisions at a faster rate. However, the opposite was found, probably because the standard incision length for PIT tagging was proportionally more severe to them than to

Ž .

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days incisions representing less than 0.5% of their body length, whereas longer incisions took longer to heal. Additionally, it can not be excluded that hierarchies established in the groups of perch, restricted the access of the smallest fish to food, slowed down their growth and healing progress.

A clear difference between the growth of perch with tag ratios in the water above and

Ž .

below 1.25% was observed. Ross and McCormick 1981 found that yellow perch

Perca flaÕescens tagged with ratios higher than 1.5% could no longer maintain their

equilibrium or swim normally. However, we observed that small perch showed catch-up growth over the following days, then growth rates similar to those of larger fish and controls, although their tag ratio was still higher than 1.25%. This indicates that juvenile perch can adapt very rapidly to tag ratios lower than this value, need longer time to adapt to higher ratios, but apparently can adapt completely to these within less than two weeks. This interpretation agrees with the conclusions of Claireaux and Lefranc

¸

ois

Ž_{1998 , Martinelli et al., 1998 and Baras et al., 1999 that high tag ratios can be used}. Ž . Ž .

without causing substantial biases in the long run. The observation that the development of gonads and capacity of perch to store reserves of abdominal fat, were unaffected by tagging or tag presence in all weight classes, also supports this statement.

Implanted tags caused no internal damage, presumably because their midventral location excluded most contacts with organs, and associated risks of erosion. The encapsulation of most tags by host tissue, and the resulting limited migration of tag

inside the cavity may have contributed to reduce this risk too see Pedersen and

Andersen, 1985; Lucas, 1989 . Tag encapsulation has often been associated with a

Ž .

higher risk of expulsion since Marty and Summerfelt 1986, 1990 have showed that tag capsules contain myofibroblasts, which contract and add to the gravity pressure by the negatively buoyant tag over the fish tissue, resulting into the eventual expulsion of the tag. In this study, as in other studies with PIT-tags or epoxy dummies, which eventually

became encapsulated Thoreau and Baras, 1997; Baras and Jeandrain, 1998; Baras et al.,

1999 , tag retention was 100%. Considering that the gravity pressure by the tag rapidly decreases in a fast growing juvenile, the risk of later expulsion through the body wall is

deemed to be minimal. Similarly, there was little risk of transintestinal expulsion see

Marty and Summerfelt, 1986; Baras and Westerloppe, 1999 , as no capsule adhered to the intestinal peritoneum of perch.

Tag readability by hand detectors was 100% throughout the study. However, we found that tags had different orientations and thus variable chances of being

automati-Ž .

cally detected by fixed antennas F40=40 cm for TROVAN tags connected to data entry stations. This was also noted for tags inserted into the isthmus of Arctic char

Ž .

SalÕelinus alpinus Brannas and Alanara, 1993 . We observed some changes in the

¨ ¨

orientation of individual tags, which could also compromise the consistency of auto-matic detection over a long period. Considering that most tags that were, or became disorientated were near midgut, care should be taken at the time of tagging to position the tag as close as possible to the abdominal body wall. However, this additional accuracy can hardly be achieved without making a longer incision, which requires longer to heal. Assuming the combination of initial misplacement and change of orientation over time, 95% of the perch tagged with the methodology above would suffer from reductions of coupling that would not exceed 13%. Therefore, the confident

(13)

( )

E. Baras et al.rAquaculture 185 2000 159–173 171 automatic detection of perch passage could be achieved by slightly reducing the size of

Ž .

detecting antennas i.e., from 40=40 cm to 35=35 cm .

5. Conclusions

These different elements indicate that a reliable technique has been developed to PIT tag juvenile perch as small as 2 g, and permit to schedule more accurately studies relying on the use of PIT tags and data entry stations. Basically, the only shortcomings refer to the early growth impairment and time for healing, which suggest that the collection of biological data from tagged perch be postponed by 2–3 weeks after tagging. This would still permit to investigate the behaviour of juvenile perch weighing less than 3.0 g, and opens promising perspectives for the studies of their activity rhythms, access to food and social interactions.

Acknowledgements

Ž .

This study was part of EU contract FAIR CT96-1572 DG XIVrC2 . The authors wish to thank Electrabel s.a. for supporting the fish culture programmes at the University of Liege.

`

References

Alanara, A., Brannas, E., 1993. A test of the individual feeding activity and food size preference in rainbow¨ ¨ ¨ ¨ trout using demand feeders. Aquacult. Int. 1, 47–54.

Alexander, R.M., 1966. Physical aspects of swim bladder function. Biol. Rev. 41, 141–176.

Anderson, C.D., Roberts, R.J., 1975. A comparison of the effects of temperature on wound healing in a tropical and temperate teleost. J. Fish Biol. 7, 173–182.

Armstrong, J.D., Braithwaite, V.A., Rycroft, P., 1996. A flat-bed passive integrated transponder antenna array for monitoring behaviour of Atlantic salmon parr and other fish. J. Fish Biol. 48, 539–541.

Ž .

Baras, E., 1992. Time and space utilisation modes and strategies by the common barbel, Barbus barbus L. . Cah. Ethol. 12, 125–442.

Baras, E., 1999. Sibling cannibalism among juvenile vundu under controlled conditions: I. Cannibalistic behaviour, prey selection and prey size-selectivity. J. Fish Biol. 54, 82–105.

Baras, E., Birtles, C., Westerloppe, L., Thoreau, X., Ovidio, M., Jeandrain, D., Philippart, J.C., in press. A critical review of surgery techniques for implanting telemetry devices into the body cavity of fish. In: Y.

Ž .

Le Maho Ed. , Proceedings of the 5th European Conference on Wildlife Telemetry. CNRS, Strasbourg, France, 12 pp.

Baras, E., Jeandrain, D., 1998. Evaluation of surgery procedures for tagging eel Anguilla anguilla with telemetry transmitters. Hydrobiologia 371–372, 107–111.

Baras, E., Westerloppe, L., 1999. Transintestinal expulsion of surgically implanted tags in African catfishes Heterobranchus longifilis of different size and age. Trans. Am. Fish. Soc. 128, 737–746.

Baras, E., Westerloppe, L., Melard, C., Philippart, J.C., Benech, V., 1999. Evaluation of implantation´ ´ procedures for PIT tagging juvenile Nile tilapia. N. Am. J. Aquacult. 61, 246–251.

Brannas, E., Alanara, A., 1993. Monitoring the feeding activity of individual fish with a demand feeding¨ ¨ ¨ ¨ system. J. Fish Biol. 42, 209–215.

(14)

Brannas, E., Lundqvist, H., Prentice, E., Schmitz, M., Brannas, K., Wiklund, B.S., 1994. Use of the passive¨ ¨ ¨ ¨

Ž .

integrated transponder PIT in a fish identification and monitoring system for fish behavioural studies. Trans. Am. Fish. Soc. 123, 395–401.

Claireaux, G., Lefranc¸ois, C., 1998. A method for the external attachment of acoustic tags on roundfish. Hydrobiologia 371–372, 113–116.

Collins, M.R., Smith, T.I.J., Heyward, L.D., 1994. Effectiveness of six methods for marking juvenile shortnose sturgeons. Prog. Fish-Cult. 56, 250–254.

Craig, J.F., 1987. The Biology of Perch and Related Fish. Croom Helm, Beckenham.

Greenstreet, S.P.R., Morgan, R.I.J., 1989. The effects of ultrasonic tags on the growth rates of Atlantic salmon, Salmo salar L., parr of varying size just prior to smolting. J. Fish Biol. 35, 301–309.

Grignard, J.C., Melard, C., Baras, E., Poirier, A., Bussers, J.C., Philippart, J.C., 1996a. Occurrence and impact´

Ž .

of Heteropolaria Protozoa: Ciliophora , on intensively cultured perch Perca fluÕiatilis. Ann. Zool. Fenn.

33, 653–657.

Grignard, J.C., Melard, C., Kestemont, P., 1996b. A preliminary study of parasites and diseases of perch in an´ intensive culture system. J. Appl. Ichthyol. 12, 195–199.

Guerrero, R.D., Shelton, W.L., 1974. An aceto-carmin squash method for sexing juvenile fishes. Prog. Fish-Cult. 36, 56.

Jenkins, W.E., Smith, T.I.J., 1990. Use of PIT tags to individually identify striped bass and red drum brood stocks. Am. Fish. Soc. Symp. 7, 341–345.

Jobling, M., Baardvik, B.M., Jorgensen, E.H., 1989. Investigations of food-growth relationships of Arctic char SalÕelinus alpinus L., using radiography. Aquaculture 81, 367–372.

Knights, B.C., Lasee, B.A., 1996. Effects of implanted transmitters on adult bluegills at two temperatures. Trans. Am. Fish. Soc. 125, 440–449.

Lucas, M.C., 1989. Effects of implanted dummy transmitters on mortality, growth and tissue reaction in rainbow trout, Salmo gairdneri Richardson. J. Fish Biol. 35, 577–587.

Mallison, J.A., Kayes, T.B., Best, C.D., Amundson, C.H., Wentworth, B.C., 1986. Sexual differentiation and

Ž .

the use of hormones to control sex in yellow perch Perca flaÕescens . Can. J. Fish. Aquat. Sci. 43,

26–35.

Martinelli, T.L., Hansel, H.S., Shively, R.S., 1998. Growth and physiological responses to surgical and gastric

Ž .

radio transmitter implantation techniques in subyearling Chinook salmon Oncorhynchus tshawytscha . Hydrobiologia 371–372, 79–87.

Marty, G.D., Summerfelt, R.C., 1986. Pathways and mechanisms for expulsion of surgically implanted dummy transmitters from channel catfish. Trans. Am. Fish. Soc. 115, 577–589.

Marty, G.D., Summerfelt, R.C., 1990. Wound healing in channel catfish by epithelialization and contraction of granulation tissue. Trans. Am. Fish. Soc. 119, 145–150.

McCarthy, I.D., Houlihan, D.F., Carter, C.G., 1994. Individual variation in protein turnover and growth

Ž .

efficiency in rainbow trout, Oncorhynchus mykiss Walbaum . Proc. R. Soc. London, Ser. B 257, 141–147.

Melard, C., Kestemont, P., Grignard, J.C., 1996. Intensive culture of juvenile and adult Eurasian perch P.´

fluÕiatilis : effect of major biotic and abiotic factors on growth. J. Appl. Ichthyol. 12, 175–180.

Moore, A., Russell, I.C., Potter, E.C.E., 1990. The effects of intraperitoneally implanted dummy acoustic transmitters on the behaviour and physiology of juvenile Atlantic salmon, Salmo salar L. J. Fish Biol. 37, 713–721.

Pedersen, B.H., Andersen, N.G., 1985. A surgical method for implanting transmitters with sensors into the

Ž .

body cavity of the cod Gadus morhua L. . Dana 5, 55–62.

Peterson, N.P., Prentice, E.F., Quinn, T.P., 1994. Comparison of sequential coded wire and passive transponder tags for assessing overwinter growth and survival of juvenile coho salmon. N. Am. J. Fish. Manage. 14, 870–873.

Prentice, E.F., Flagg, T.A., McCutcheon, C.S., 1990a. Feasibility of using implantable passive integrated

Ž .

transponder PIT tags in salmonids. Am. Fish. Soc. Symp. 7, 317–322.

Prentice, E.F., Flagg, T.A., McCutcheon, C.S., Brastow, D.F., 1990b. PIT-tag monitoring systems for hydroelectric dams and fisheries. Am. Fish. Soc. Symp. 7, 323–334.

Prentice, E.F., Flagg, T.A., McCutcheon, C.S., Brastow, D.F., Cross, C.S., 1990c. Equipment, methods and an automated data-entry station for PIT tagging. Am. Fish. Soc. Symp. 7, 335–340.

(15)

( )

E. Baras et al.rAquaculture 185 2000 159–173 173 Prentice, E.F., Park, D.L., Sims, C.W., 1984. A study to determine the biological feasibility of a new fish

Ž .

tagging system. Report contract DE-A179-83BP1192, project 83-19 to Bonneville Power Administration, Portland, OR.

Roberts, R.J., MacQueen, A., Shearer, W.M., Young, H., 1973. The histopathology of salmon tagging: I. The tagging lesion in newly tagged parr. J. Fish Biol. 5, 497–503.

Ross, M.J., McCormick, J.H., 1981. Effects of external radio transmitters on fish. Prog. Fish-Cult. 43, 67–73. Summerfelt, R.C., Smith, L.S., 1990. Anesthaesia, surgery, and related techniques. In: Schreck, C.B., Moyle,

Ž .

P.B. Eds. , Methods for Fish Biology. American Fisheries Society, Bethesda, MD, pp. 213–272. Thoreau, X., Baras, E., 1997. Evaluation of surgery procedures for implanting telemetry transmitters into the

body cavity of blue tilapia Oreochromis aureus. Aquat. Liv. Resour. 10, 207–211.

Ž .

Winter, J.D., 1983. Underwater biotelemetry. In: Nielsen, L.A., Johnsen, D.L. Eds. , Fisheries Techniques. American Fisheries Society, Bethesda, MD, pp. 371–395.

(1)

Ž_P)0.10 . Tags near midgut showed significantly P. Ž -0.0001 stronger deviations and. Ž

changes over time than those located near the abdominal body wall mean deviations of

(2)

Dissection on day 126 revealed no muscle necrosis, erythema, infection nor damage

Ž .

to internal organs. Most tags had become embedded in the adipose tissue 21.7% , or

Ž .

encapsulated into a fibrous capsule inside the adipose tissue 60.3% . Capsules adhered

Ž . Ž .

to the parietal 7.4% or visceral peritoneum 4.8% , but never to the intestine. The

Ž .

remaining tags 5.8% were free in the body cavity of individuals with less adipose

Ž 2

tissue than others. The host tissue response to the tag was independent of fish sex x ,

. Ž 2 _.

Ps0.7930 and was unaffected by the tag ratio x , Ps0.4851 .

4. Discussion

Surgery was adequate for PIT tagging juvenile perch, as the mortality of sutured tagged fish did not differ from that of controls, and was low compared to standards in

Ž .

perch culture Grignard et al., 1996b . Syringe injectors were less adequate than surgery techniques in an environment with fish pathogens, and this corroborated recent results in

another warmwater Percomorph, the Nile tilapia Oreochromis niloticus Baras et al.,

. Ž .

Ž .

osmotic balance Anderson and Roberts, 1975 but the presence of the stitch compro-mised the growth of perch. This is a further example to the potential detrimental effect

of transcutaneous foreign bodies reported previously by several authors Roberts et al., 1973; Baras, 1992; Collins et al., 1994; Thoreau and Baras, 1997; Baras and Jeandrain,

1998 , and indicates that the stitch should be removed as soon as the fish has healed its incision. Considering the risks of microbial outbreak, the use of antibiotic powders

Ž_{terramycin, oxytetracycline, penicillin G, etc. that are injected into the caudal pedun-}.

cle, body cavity or applied as a mudpack over the incision, may be worth considering for PIT tagging perch.

On average, tagged perch healed their incision within 12–13 days at 22–238C. This is

Ž .

slower than juveniles of tropical species 7–10 days; Baras et al., 1999, in press ,

slightly faster than juveniles of cold-water species ca. 14 days; Moore et al., 1990;

Prentice et al., 1990a and about twice as fast as adults of temperate species healing an

incision of a similar relative length 4–6 weeks; Pedersen and Andersen, 1985; Baras,

1992; Knights and Lasee, 1996 . The dynamics of wound healing, which involves tissue resorption then reconstitution, is a function of the main variables that influence fish

growth, including species, life stage, metabolism and temperature Anderson and

Ž .

(3)

A clear difference between the growth of perch with tag ratios in the water above and

Ž .

below 1.25% was observed. Ross and McCormick 1981 found that yellow perch

Perca flaÕescens tagged with ratios higher than 1.5% could no longer maintain their

¸

ois

Ž_{1998 , Martinelli et al., 1998 and Baras et al., 1999 that high tag ratios can be used}. Ž . Ž .

inside the cavity may have contributed to reduce this risk too see Pedersen and

Andersen, 1985; Lucas, 1989 . Tag encapsulation has often been associated with a

Ž .

became encapsulated Thoreau and Baras, 1997; Baras and Jeandrain, 1998; Baras et al.,

1999 , tag retention was 100%. Considering that the gravity pressure by the tag rapidly decreases in a fast growing juvenile, the risk of later expulsion through the body wall is

deemed to be minimal. Similarly, there was little risk of transintestinal expulsion see

Marty and Summerfelt, 1986; Baras and Westerloppe, 1999 , as no capsule adhered to the intestinal peritoneum of perch.

Tag readability by hand detectors was 100% throughout the study. However, we found that tags had different orientations and thus variable chances of being

automati-Ž .

cally detected by fixed antennas F40=40 cm for TROVAN tags connected to data

entry stations. This was also noted for tags inserted into the isthmus of Arctic char

Ž .

SalÕelinus alpinus Brannas and Alanara, 1993 . We observed some changes in the

¨ ¨

(4)

automatic detection of perch passage could be achieved by slightly reducing the size of

Ž .

detecting antennas i.e., from 40=40 cm to 35=35 cm .

5. Conclusions

Acknowledgements

Ž .

This study was part of EU contract FAIR CT96-1572 DG XIVrC2 . The authors

wish to thank Electrabel s.a. for supporting the fish culture programmes at the University of Liege.

`

References

Alanara, A., Brannas, E., 1993. A test of the individual feeding activity and food size preference in rainbow¨ ¨ ¨ ¨ trout using demand feeders. Aquacult. Int. 1, 47–54.

Alexander, R.M., 1966. Physical aspects of swim bladder function. Biol. Rev. 41, 141–176.

Anderson, C.D., Roberts, R.J., 1975. A comparison of the effects of temperature on wound healing in a tropical and temperate teleost. J. Fish Biol. 7, 173–182.

Ž .

Baras, E., 1992. Time and space utilisation modes and strategies by the common barbel, Barbus barbus L. . Cah. Ethol. 12, 125–442.

Baras, E., 1999. Sibling cannibalism among juvenile vundu under controlled conditions: I. Cannibalistic behaviour, prey selection and prey size-selectivity. J. Fish Biol. 54, 82–105.

Ž .

Le Maho Ed. , Proceedings of the 5th European Conference on Wildlife Telemetry. CNRS, Strasbourg, France, 12 pp.

Baras, E., Jeandrain, D., 1998. Evaluation of surgery procedures for tagging eel Anguilla anguilla with telemetry transmitters. Hydrobiologia 371–372, 107–111.

Baras, E., Westerloppe, L., 1999. Transintestinal expulsion of surgically implanted tags in African catfishes

Heterobranchus longifilis of different size and age. Trans. Am. Fish. Soc. 128, 737–746.

Baras, E., Westerloppe, L., Melard, C., Philippart, J.C., Benech, V., 1999. Evaluation of implantation´ ´ procedures for PIT tagging juvenile Nile tilapia. N. Am. J. Aquacult. 61, 246–251.

Brannas, E., Alanara, A., 1993. Monitoring the feeding activity of individual fish with a demand feeding¨ ¨ ¨ ¨ system. J. Fish Biol. 42, 209–215.

(5)

Brannas, E., Lundqvist, H., Prentice, E., Schmitz, M., Brannas, K., Wiklund, B.S., 1994. Use of the passive¨ ¨ ¨ ¨

Ž .

integrated transponder PIT in a fish identification and monitoring system for fish behavioural studies. Trans. Am. Fish. Soc. 123, 395–401.

Claireaux, G., Lefranc¸ois, C., 1998. A method for the external attachment of acoustic tags on roundfish. Hydrobiologia 371–372, 113–116.

Collins, M.R., Smith, T.I.J., Heyward, L.D., 1994. Effectiveness of six methods for marking juvenile shortnose sturgeons. Prog. Fish-Cult. 56, 250–254.

Craig, J.F., 1987. The Biology of Perch and Related Fish. Croom Helm, Beckenham.

Greenstreet, S.P.R., Morgan, R.I.J., 1989. The effects of ultrasonic tags on the growth rates of Atlantic salmon,

Salmo salar L., parr of varying size just prior to smolting. J. Fish Biol. 35, 301–309.

Grignard, J.C., Melard, C., Baras, E., Poirier, A., Bussers, J.C., Philippart, J.C., 1996a. Occurrence and impact´

Ž .

of Heteropolaria Protozoa: Ciliophora , on intensively cultured perch Perca fluÕiatilis. Ann. Zool. Fenn.

33, 653–657.

Grignard, J.C., Melard, C., Kestemont, P., 1996b. A preliminary study of parasites and diseases of perch in an´ intensive culture system. J. Appl. Ichthyol. 12, 195–199.

Guerrero, R.D., Shelton, W.L., 1974. An aceto-carmin squash method for sexing juvenile fishes. Prog. Fish-Cult. 36, 56.

Jenkins, W.E., Smith, T.I.J., 1990. Use of PIT tags to individually identify striped bass and red drum brood stocks. Am. Fish. Soc. Symp. 7, 341–345.

Jobling, M., Baardvik, B.M., Jorgensen, E.H., 1989. Investigations of food-growth relationships of Arctic char

SalÕelinus alpinus L., using radiography. Aquaculture 81, 367–372.

Knights, B.C., Lasee, B.A., 1996. Effects of implanted transmitters on adult bluegills at two temperatures. Trans. Am. Fish. Soc. 125, 440–449.

Lucas, M.C., 1989. Effects of implanted dummy transmitters on mortality, growth and tissue reaction in rainbow trout, Salmo gairdneri Richardson. J. Fish Biol. 35, 577–587.

Mallison, J.A., Kayes, T.B., Best, C.D., Amundson, C.H., Wentworth, B.C., 1986. Sexual differentiation and

Ž .

the use of hormones to control sex in yellow perch Perca flaÕescens . Can. J. Fish. Aquat. Sci. 43,

26–35.

Martinelli, T.L., Hansel, H.S., Shively, R.S., 1998. Growth and physiological responses to surgical and gastric

Ž .

radio transmitter implantation techniques in subyearling Chinook salmon Oncorhynchus tshawytscha . Hydrobiologia 371–372, 79–87.

Marty, G.D., Summerfelt, R.C., 1986. Pathways and mechanisms for expulsion of surgically implanted dummy transmitters from channel catfish. Trans. Am. Fish. Soc. 115, 577–589.

Marty, G.D., Summerfelt, R.C., 1990. Wound healing in channel catfish by epithelialization and contraction of granulation tissue. Trans. Am. Fish. Soc. 119, 145–150.

McCarthy, I.D., Houlihan, D.F., Carter, C.G., 1994. Individual variation in protein turnover and growth

Ž .

efficiency in rainbow trout, Oncorhynchus mykiss Walbaum . Proc. R. Soc. London, Ser. B 257, 141–147.

Melard, C., Kestemont, P., Grignard, J.C., 1996. Intensive culture of juvenile and adult Eurasian perch P.´

fluÕiatilis : effect of major biotic and abiotic factors on growth. J. Appl. Ichthyol. 12, 175–180.

Pedersen, B.H., Andersen, N.G., 1985. A surgical method for implanting transmitters with sensors into the

Ž .

body cavity of the cod Gadus morhua L. . Dana 5, 55–62.

Prentice, E.F., Flagg, T.A., McCutcheon, C.S., 1990a. Feasibility of using implantable passive integrated

Ž .

transponder PIT tags in salmonids. Am. Fish. Soc. Symp. 7, 317–322.

Prentice, E.F., Flagg, T.A., McCutcheon, C.S., Brastow, D.F., 1990b. PIT-tag monitoring systems for hydroelectric dams and fisheries. Am. Fish. Soc. Symp. 7, 323–334.

Prentice, E.F., Flagg, T.A., McCutcheon, C.S., Brastow, D.F., Cross, C.S., 1990c. Equipment, methods and an automated data-entry station for PIT tagging. Am. Fish. Soc. Symp. 7, 335–340.

(6)

Prentice, E.F., Park, D.L., Sims, C.W., 1984. A study to determine the biological feasibility of a new fish

Ž .

tagging system. Report contract DE-A179-83BP1192, project 83-19 to Bonneville Power Administration, Portland, OR.

Roberts, R.J., MacQueen, A., Shearer, W.M., Young, H., 1973. The histopathology of salmon tagging: I. The tagging lesion in newly tagged parr. J. Fish Biol. 5, 497–503.

Ž .

body cavity of blue tilapia Oreochromis aureus. Aquat. Liv. Resour. 10, 207–211.

Ž .

Winter, J.D., 1983. Underwater biotelemetry. In: Nielsen, L.A., Johnsen, D.L. Eds. , Fisheries Techniques. American Fisheries Society, Bethesda, MD, pp. 371–395.

Directory UMM :Data Elmu:jurnal:A:Aquaculture:Vol185.Issue1-2.May2000:

The effect of PIT tags on growth and physiology of

age-0 cultured Eurasian perch Perca flu

Õ

iatilis of

variable size

Etienne Baras

, Christelle Malbrouck

, Marc Houbart

,

Patrick Kestemont

, Charles Melard

´

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¨ ¨

¨

¨

¨ ¨

¨ ¨

¨

¨

¨ ¨

¸

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´

¸

¨ ¨

¨ ¨

`

¸

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