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PAPER
ICES 1992
Demersal Fish Committee
C.M. 19921G:66
Re/. F
SruDIES ON ASSOCIATIONS BETWEEN GENOTYPES AND
GROWTH RATE OF O·GROUP COD
By
Knut E. J~rstad
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Institute of Marine Research
P.O.Box 1872, Nordnes
N-5024 BERGEN - Norway
and
Gunnar Nrevdal
Department of Fisheries and Marine Biology
University of Bergen
Bergen High-Technology Center
N-5020 BERGEN - Norway
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ABSTRAcr
The aim of the present study was to investigate genotype dependent growth rate in young eod.
The material of O-group cod was colleeted from pond produced eod in western and northern
Norway, and analysed for genotype distribution of haemoglobins and several tissue enzymes.
The mean growth rate (meastlI'ed as size at sampling) of the different genotypes were
compared by analyses of variance. Associations between growth rate and haemoglobin type
were found in one sampIe, and likewise LDH genotype dependent growth rate was indieated
in one sampie. The results are discussed in relation to the biological significance of
biochemical genetic variation.
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INTRODUCTION
Studies on' blood types and blood proteins of eod, Gadus. morhua wer~ eondueted in Norway .
in the years' 1962- 1972 (FrydenbCrg' et al. 1965, Mpllcr 1968 and unpublished) for
appIleations on ideritificatiori of sclf-sustaining populations of this spccies. Sincc 1978
likewise tissue enzymes have 1>Cen siudicd by stareh gei cicetrophoresis (iprstäd 1984 arid
unpublished, J~rsiad & Nrevd1l11989, Gjpsreter et al. 199I). The more rceent studies have
bcen eoriducted as bascline studies in connection with aftlficial propagation and sca nmching
of eod. .'
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Kaipov & Novikov (1980) found that the furictional propeities of the haemoglobin genotyPes
of eod were differentially iriOueneed by environrriental ternperature. Likewise Mork~
GiskepdegäTd & Sundnes (1984, a,b) found that tbe three ~acmoglobin genotypes possessed ,
different growth rate .capacities, and Mork & Sundnes (1985) found different survival of
different Ldh-3 arid ,/>gi-1 genotypes of wild eaptured O-group eod which were kept in
captivitY.· Jßrstäd (1986) found no genotyPe depende'nt groWth rate in an extensive sarnpling,'
programme of eod produced in a marine pond. while Gjpsreter et al. (1992) fouod indieation.
although not eonsistently, of ge~oiyPc deperident growth rate in O-group cod from the
southeasi eoast of Norway.
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, ·Tbe aim of ihe prescnt stucty was to investigate poteritial genritypc depcrideöt growih riüe in
O-group eod raised in semi-natural ponds for usc in sea ranehing. The resultS will bc of value
for understanding the significance of biochemical genetic variation and for the application of
gerie frequencies or/and geriotype distributions in studies of populations structure in this and
other fish species.
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MATERIAL AND METHODS
Sarripling of blood and tissüe have been dcscribcd by MplIer (1968) arid j~rstad (1984). For
analysis of hacmoglobin. the method describcd by Siek (1965) ~as applied with modifieations
(Jprstad 1984). Starch,gel electfophoresis was used for analysis of tissue enzymes. After an
initial sCreening of a large numbcr of enzymes to identify polymorPhic loci, the following
were chosen for routine analyses; lactatC' dehydrogeöasc (LDH-3), phosphogluco-J!lutase
(PGM), glucose-6-phosphatri dehydrogenaSe (GPD). phosphoglucoSc isomerase (PGI-l),arid
.'isoeitraie dehydrogenasc (IDH-2). ,For the present änalYsis. the genetie systems with a
. reasonably high numbcr of sPccimens within two or more genotype groups withm sampIes
,were chosen i.e. haemoglobin, LDH and PGI. .
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An overview of thesamples is given inTable.L All sampIes were eoUected in the autllmn
when the flsh were 4-6 months old and chose to the time of release of the fish inti> the riatirral' .
environment. Sainples 1-3 were coIiected from eod produced in a porid near Tromsp while
the rest of the ·samples.were ~wn fro~.eod produced iri,ihc pond Parisvarine4located mi
island west of Bergen. In 1990 and 1991 two groups of fish were' produced iIi. the pond;
orie offspring of non-sciectCd broodfish. arid one, offspririg of geneiieally tagged broodfish~
11te productionof broodfishhomozygotous for the rare a1le~e Pgi-l(30ßO)is desenbed by
Skäala et ale (1990) and Svasand er al. (1990). Offspring of the geneiically tagged broodflsh;
(ealled 6a arid ja) are treated ~ iwo gioups.·
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Individu~ length were reeorded for all fish sampled. ,Lcngth at time of sampling is regarded
as a measuremcnt of realized growth rate from hatchirig to sampling. Mean lengths wiihin
frequent genotypes were coiriparcd, by ,one-way and two-ways ANOVA statistics.
RESULTS AND DISCUSSION
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, , Gene frequencies calculated from obse~ed genotype distributions are shown in Table 1.
. Considerable variations bCtween sainpJes were found. Frequencies of the gene Hb-I(1) in the
range 0.25 '-0.40 for coastal eod in northern NOrWay and in the ran'ge 0.50,-0.60 in western
Norway arC in aceordance with eadier findings (Frydenbcrg et al.' 1965. Mßller 1968. ]prstad
and Nrevdal 1989). whiJe the frequencies of the more eommon LDH and PGI genes wece
fOllnd io bc vcry' high in some of the present sampies eompared to earlier findings (Jprstad
1984. ]prstad and Nrevdal 1989). Likewise rare genes seemed io bC absent or extremely rare
in some sanipJes. As expeeted in the sampJes 6a and 7a only the POl gene Pgi-3(30) is
represented while the other genetic systems are unaffected. However. it is not at all sure that
the gene frequencies in pond produced fish afe representative for the populations from which
lhe broodfish were drawn. bCcausc these frequencies probably are influenced by genetic drift.
Although the numbC..s of spawning eod in the spawning pond are high (Sväsand et eil. 1990).
the 'actual numbcrs participaiing in the spawning the few days the eggs were collected. are
unknowri and'probably low. Thus genetic drift is IikeJy to take piace. and too much weight
should not bc pui on the variation bctween samjlles.
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Mean lengths' of fish of different gen~types within ~ampJes ~. shown in TabJ~s 2-4. These
vatues were tested by one-way ANOVA within sampies. arid by two-ways ANOVA for all
or groups of sampies. Conceming haemoglobins significant differences were found in sampie
No. 4; fish of genotype Hb-I(212) showing the highest mean lerigth. This is in aceordance with
tlle resuJts of Moik et al. (1984 a.b). and Nrevdai et al. (1992). fouod highest mean le~gths
of Hb-I(212) regardlesS of environmental temperature under experimental conditions. No trend
or tendencies were seen among the non-significant differences. and two-ways ANOVAgave
no indication of significant interactions bctween genotype and sampie conccinirig, mean
lengths.
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.Likewisc only orie sainpld (s~ple 6) showed significant differenc~s in mean length
concerning LDH genotype. No sign'of interactions were found arid no trend among the norisignificant differenees. cxcept that ihegenetically iagged eod (Pgi-3(30/30) were on average
smaller in 1990 and larger iri 1991 thanthe rest of the fish raised inthe same pond. This.
however. Me due to differences in age ai start of the pond experiment and not associated with
genotype (Biom 'et al. 1990).
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Thus the preserit study have shown indication of genotype dependent groWth rate in only two
.cases of totally 27 comparisons. However. the results ace not c·onsistent. 'and the differences
are showing up only'in a few Sarriph~s. This,is in accordaricc with earlier findings (GjPsreter
er al. 1992) and the biological significance of biochemical genetic .variation in fish still serims
obscure.·, .
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ACKNOWLEDGEMENTS
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want to thank Torstein pederSen. Oie lrigar Paulsen and Solve.ig Thorkiidscn for
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sampling and laboratoiy analyscs, and the NoiWegi~ Fish~ries Research Council for'Financial
'support.'
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REFERENCES
BIom, G., SvAsand, To, J~rsiad, K., Otterä, H.~ PauISen, O.I~ and Holm, J. Chr. i990.
eomparative growth and survival of lwo genetie strains of Atlantie eod (Gculus morhua
· L.) rcared through. the early' life stages in' a' marine pond iIi western NOrWay.
. Coun.Meet. Int.CC!ün.EXplor.Sea 1990 (F: 48), 19 pp.
.
Frydenbcrg, 0., M~ller, D., Nrevdal, G. and Siek, K. 1965. Haemoglobin p~lymOl.phism in.
· Norwegian eod populations. Hereditlis, '53: 257-271.. ,
. Gj~sreter, 1.. J~rstad, K. Nrevdal, G. and Thorkildscn~ S. 1992. Genotype distributions of eod
·
from the Norwegian Skag~iTak eoast. Sarsia 76: 255-259. ' .
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J~rsuid,K.1984:Geneiie äriaiyses of eod irinortherii Norway. In: E. Dahl, DoS. D~ielssen,
. " E. Mokiness tind P. SoleiiuJal (ed;ts), The Propagation
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0/ eod, GluJus morhua,' 1.
Fl;devigen rapportser.; 1'(1984): 745-760.
.
J~rstad, K. 1986. Growth studies on eod (Ga'dus morhua L.): eompansons bCtween gcnoiypes
identifled byelectrophorcsis. EIFAClFAO Symposium on Seleetion, Hybridization and
-Genetie Engineering- in .Aquaculture
Fish and SheÜfish. for Consumption and
Stcicking:-Bordeaux (Franee),' 27-30 Mciy, 1985(posie;)~', .
oe,
J~rStad, K. and Nrevdal; G. 1989. Genctlc variationand popuiaii~n strueture of'eod; GQdus
·
. mOrhua L;, in some fjords in northern Norway. J.Fish.Biolo; 35 (Supplement A): 245.' , 252.
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Kaipo, L.K. and Novikov, G.G. 1980. The häe~oglobin allofoJms in eod (GaduS morhua L.),
their functional eharacteristies arid distribution in' the populations (Trarislated from
rUssian). Voprosy iehtiologii (T.20), 6 (125): 82.3.827.
.
. Mork, J. t Giske~degärd and'Suridncs, G. 1984a, The hacmoglobin polymorphisnt'in Atlaniie .
eod (Giulus morhua L.): Gcnotype differences in somatlc growth arid in maiuiing age
in .riatiIral populations. In: E. 'Dahi, D.S. jjanielssen, E. Moksn,ess lUuJ P. Solemdal
.' (edits), The Propagation 0/ eod Gadus mOrhua, 1., FI;devige~ rapportser.;l (984):
721-732.
Mork, 1., Giske~degärd and Sundne~~ ci: i984b. Population gencitic' studics on coa '(GaduS
· mOrhua L) by means o(the hae~oglobin polyiri~iphislll; observation in a Norwegian
· emisiaI'population. fiskDir. Sf,..S~r.HavUnders.,! 7: 449~?1.,'
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Mork, i and Sundncs, G. 1985. O-group eOd (Gadus morhua) in eaptivity: differential s~v31
of eertain genotypes. HeIgoi. Meeresunters, 39: 63-70.
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'M~ller,ri~ 1968. Gcnetlc divecsity 'in spawning.cod along the N.o~egiari cOaSLHereditas, .
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60 (1):1-32. .. '
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Nrevdal, G., Folkvord, A., Otterlei E. and Thorkildsen, S. 1992. Growth rate related to
genotype of O-group eod at three environmental temperatures. Sarsia 77: 71-73.
Skaala,
0., Dahle, G., J~rstad, K.E. and Nrevdal, G. 1990. Interactions between natural and
farmed fish populations: infonnation from genetie markers. J.Fish.Biol. 36: 449-460.
Sväsand, T., J~rstad, K. and Kristiansen, T.S. 1990. Enhancement studies of eoastal eod in
western Norway. Part I. Reeruitment of wild and reared eod to a Iocal spawning stock.
J.Cons.lnt.Explor. Mer, 47: 5-12.
Table 1.
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Allele frequencies in samples of O-group cod produced in marine ponds for stocking
purposes. 6a and 7a represe~t samples of genetically tagged cod i.e. off spring of boodstock
homozygotous for the gene Pg~-l(30} .
Sample no.
Locality
Hb-I
2
70
.69
.76
.76
.39
.60
.41
.36
.3B
.26
.56
.61
.62
.74
.25
.74
1
TROMS0
1987
140
2
TROMS0
TROMS0
1988
1989
191
172
.31
.24
.24
19BB
19B9
1990
2B6
252
.5B
.47
145
.57
3
4
PARISVANNET
PARISVANNET
PARISVANNET
5
6a
Ldh-3
1
.42
.53
.43
100
150
Pgi-l
30
70
.01
.02
.03
.03
.03
.02
.01
.01
.01
6b
PAR I SVANNET
1990
160
.62
.38
.32
.68
7a
1. 00
.13
PARISVANNET
1991
243
.5B
.42
.32
.68
7b
1.00
PARISVANNET
1991
162
.55
.45
.43
.57
.02
100
150
.01
.63
.34
.02
.63
.61
.76
.02
.83
.34
.38
.21
.13
.71
.16
.70
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Table 2. Mean lengths (in mm) of cod of different haemoglobin types.
s: standard error. n: numbers
One sample showing significant genotype dependent
1ength variation is underlined.
Sample no.
Hb-I(1I1)
T
1
Hb-I(1I2)
T
Hb-I(2/2)
s
n
14
147.2
1.6
56
145.1
9
12
146.3
147.5
142.4
3.0
2.3
72
164.2
156.6
102.9
2
3
4
150.9
131. 7
143.3
3.6
8.7
5.4
.!!.1d
1.5
94
5
6
7
162.5
156.3
102.8
2.8
2.2
3.0
54
107
110
s
n
T
s
n
1.3
57
139
1.9
2.4
1.7
64
147.5
148.2
1.2Q..&
2.3
1.5
2.1
1.7
127
135
167
161.6
157.5
100.6
2.3
3.0
2.6
106
97
48
70
53
66
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Table 3. Mean lengths (in mm) of cod of different LDH genotypes. s: standard error.
n: numbers
One sample showing significant genotype dependent
length variation is underlined
Sampie no.
Ldh-] (70/70)
1:
Ldh-] (70/l00)
s
n
T
Ldh-] (lOO/lOO)
s
n
1
76
82
77
96.0
1
2
142.1
141.4
3.6
4.5
19
33
146.8
149.1
1.5
3.0
3
147.4
4.1
23
147.6
1.7
4
144.0
2.2
46
142.1
1.3
5
168.5
4.4
6
7
172.8
4.6
3.4
23
27
162.6
156.8
1.9
2.2
132
89
120
53
101.1
1.6
188
99.8
s
n
146.7
2.1
48
146.0
147.7
3.1
2.4
63
145.9
162.7
1.7
1.6
ill...1.
1.8
1.6
62
107
140
156
165
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Table 4. Mean lengths (in mm) of cod of different PGI-genotypes.
s: standard error. n: numbers
Sampie no.
Pgi-l (3D/30)
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s
n
Pgi -1 (100/1 GO)
T
Pgi-l (lOO/lOO)
Pgi-l (150/150)
s
n
1:
n
T
53
145.0
149.1
147.7
73
77
149.8
141.5
1
2
146.6
144.5
1.9
2.7
77
3
4
147.4
143.0
2.3
1.2
61
161
5
162.5
1.2
175
163.6
2.7
98.3
2.5
6a
155.9
1.8
146
6b
7a
102.8
1.5
243
7b
5
1.8
3.2
5
n
82
144.1
144.6
1.8
1.7
2.7
5.3
3.8
96
165.6
2.8
53
140.8
151.4
7.4
4.4
9
5
83
158.3
4.3
36
122.0
4.0
2
76
88.4
2.1
71
93.4
3.2
9
11
23
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