Morphological variation among four strains of common
carp Cyprinus carpio in Croatia
Tomislav TREER1*, Roman SAFNER1, Ivica ANIČIĆ1, Andrea KOLAK1 and Maja DRAŽIĆ2
1Department
of Fisheries, Beekeeping and Special Zoology, Faculty of Agriculture
University of Zagreb, Svetošimunska 25, 10 000 Zagreb Croatia;e-mail:treer@agr.hr
2Department
for Data Processing, Croatian Livestock Selection Centre, Kačićeva
9/III, 10 000 Zagreb, Croatia
Received 2 April 1998; Accepted…
A b s t r a c t . Variation in morphology among four strains of common carp in
Croatia (436 specimens) was expressed using variance (ANOVA) and cluster
analyses. Three sets of data were compared: truss network, traditional plastic
and meristic data. The results of cluster analyses were very similar for all
three data sets and were supported by ANOVA of plastic and meristic
characters. The strains differ significantly (ANOVA, P<0.05) in up to 6 plastic
and one meristic characters from all the others. It appears that there are still
some distinctive strains (one of them being from Našice farm), but also that
the lost of identity exists, probably due to uncontrolled crossbreeding and
insufficient selection work. Furthermore, these results confirm the usefulness
of the three morphologic methods in ichthyological research, as they all gave
the similar results in differentiating the strains.
Key words: morphological traits, strains, plastic characters, meristic characters,
truss network.
*
Corresponding author
Introduction
The culture of common carp (Cyprinus carpio f. domestica) in Croatia developed
considerably at the turn of 19th to 20th century. The first carp stocks were
introduced primarily from Germany and other parts of the Austro-Hungarian
empire (presently Czech Republic and Hungary). During the decades, with greater
or lesser intensity the efforts on selection evolved into well-known Našice and
Poljana strains, which are kept in the live gene bank in Szarvas (Treer & Kolak
1994; Gorda et al. 1995). The hybrids between Našice and Israeli Dor-70 strains
happen to be the most successful crossbreeds in Israel (Wohlfarth & Moav, 1990).
However, following discussions at a Budapest conference and due to uncontrolled
crossbreeding, Flajšhans & Gall (1995) supposed that the Našice strain had
disappeared from its original fish-farm.
Although artificial propagation helped the uncontrolled mixing of strains,
with young of the year from one farm being sold to several others, the fish farmers
tried to keep their own stocks (Treer et al. 1996). The purpose of the present study
was to undertake a preliminary examination of the differences in Croatia using
three types of morphological methods in ichthyology - traditional plastic, truss
network and meristic ones, using cluster analysis.
Material and Methods
The fish were taken from the following fish farms: Našice, Grudnjak, Končanica
and Draganići. These farms are situated in eastern, central and western parts of
the Croatian section of the Pannonian valley. The semi-intensive way of culturing
carps is characteristic of all of these farms. In fact, it resembles that developed in
Hungary and other central European countries (Horvath et al. 1985a; Horvath et
al. 1985b). A total of 436 marketable carp were collected during the winter harvest
season in February 1993. The fact that the gonads had not been yet fully
developed reduced their influence in discriminant function analysis. The number of
carp sampled from each farm was: Našice 110, Grudnjak 101, Končanica 109 and
Draganići 116. The carp were in their third year of life, with the following structure
of sexes and scalification types among the strains: Našice (36 scaled males, 35
scaled females, 23 mirror males, 16 mirror females), Grudnjak (14 scaled males,
10 scaled females, 43 mirror males, 34 mirror females), Končanica (19 scaled
males, 9 scaled females, 42 mirror males, 39 mirror females), Draganići (73 mirror
males, 43 mirror females).
Twenty-four
traditional plastic measurements (1 mm) were made on each
specimen (Table 1, Appendix 1), according to Baruš et al. (1998). To remove size
effects, all body length measurements were adjusted to the ratios of standard
length (SL), whereas the measurements of the head were adjusted to the ratios of
head length. Measurements for truss network analysis (Bookstein et al., 1985)
were made out of 30 distances between 16 homologous landmarks on the body
outline (Fig. 1). In the third group of morphological parameters, seven meristic
characters were counted (Table 2). Statistica for Windows (StatSoft, Inc. 1993)
was used in order to perform statistical analyses. Analysis of variance (ANOVA)
evaluates the traditional plastic and meristic characters measurements and the
significant differences (P<0.05) among them. Cluster analysis was used to
distinguish populations according to all three groups of morphological characters.
We assumed that all plastic characters grow linearly for only a short part of a
specimen’s life (Vilizzi & Walker 1999). Thus, the ratio of the particular character to
the standard length (SL) or the head length (HL) is the same for the different sized
fish from each locality. Therefore, we selected only the specimens of same age
group for this study.
Results and Discussion
Combining the results of all three methods used, it is possible to differentiate the
strains of common carp in Croatia and to explain the differences among them. In
all three cases, cluster analysis distinguished three groups of carp - the first being
Draganići, the second Grudnjak and the third one Našice and Končanica together,
which appeared to be very close (Figs. 2, 3 and 4). The results of traditional plastic
and meristic parameters were confirmed by the use of truss network. This method
proved to be very useful in the differentiation of fish populations (Edge et al. 1991;
Winemiller 1991), together with biochemical method (e.g. Karakousis et al. 1993;
Li et al. 1993; Taniguchi et al. 1996). The truss network has the advantage over
mere conventional sets of measurements that equal coverage is given to the entire
body (Swain & Holtby 1989). However, great proportion of these differences is due
to environmental conditions and disappear if two strains are cultured together
(Swain et al. 1991).
The strains of Draganići and Našice had 6 plastic parameters that differed
significantly (ANOVA P<0.05) from all the others. The strain of Grudnjak differs in
2 of them and Končanica in none of them (Table 1). Only one of meristic variables
in the strains of Draganići (no. of forked rays in D) and Našice (gill rakers) was
significantly different from all the others (ANOVA P<0.05, Table 2). Despite
indicating the lowest differences, meristic variables were of great importance
because of their high heritability characteristics, which enable them to define
different genetic origins (Tave 1993). The strain of Draganići expressed high
separation from all the others. This fish farm is situated westernmost and is the
most remote from the other three farms. It has well-organised hatchery which is a
part of the Fishery Centre.
Although cluster analysis showed great similarity between Našice and
Končanica carp strains, the carp from Našice were significantly different from the
other strains with respect to the number of gill rakers. This variable a has strong
genetic base, and differences in its number suggest genetic separation among the
strains (Lindsey et al. 1970; Loch 1974; Ihssen et al. 1981a,b). Našice farm is
situated in the easternmost part of Croatia and also uses its own hatchery.
Obviously, the original strain from this farm was maintained, although the efforts
on selection were not very intensive. Hence, the great height-length ratio
difference, typical for this strain, was slightly reduced through many generations.
This character, which can be quickly changed by selection (Ankorion et al. 1992),
is influenced by environmental conditions (Balon 1995) and transforms rapidly
towards lower values if the carp are released or escape back to nature (Treer et al.
1995).
However, the intention of keeping the height-length ratio high is obvious in
all of the farmed strains of common carp in Croatia. As a proportion of SL, the
values are: 0,440,03 for Draganići; 0,420,04 for Našice; 0,420,04 for Grudnjak
and 0,420,03 for Končanica (Table 1). Although only Draganići strain differs
significantly (P<0.05) from all the others, all four strains still fit into the up selects,
according to Ankorion et al. (1992).
The characteristics of the carp from Končanica were very close to those from
Našice strain. Encircled by other farms geographically, for years the farm
Končanica had the best organised hatchery in former Yugoslavia. However, after a
flood about ten years ago, it was closed down. Since then, some natural spawning
has been going on at that farm, but many of the young-of-the-year are being
bought every year. The Končanica and Našice farms also belonged to the same
organisation for many years. Although Grudnjak farm is in the neighbourhood of
the Našice farm, its carp stock differs a great deal from other strains. That
confirms the independent approach to culture and selection at this farm.
The results of this study indicate that there are still some well-defined
common carp strains in Croatia. On the other hand, uncontrolled mixing possibly
made some strains disappear, as it probably happened with the stock of
Končanica. Furthermore, these results confirm the usefulness of the three
morphologic methods in ichthyological research, as they all gave the similar
results in differentiating the strains. Baruš et al. (1998) stated the same
conclusion, that the classical methods in biometry still provide many useful data,
which could be used in co-ordination with more modern methods.
Appendix 1. Codes and numbers for the plastic characters measured
1. standard length (SL), 2. fork length (FL), 3. total length (TL), 4. preanal distance
(dPA), 5. preventral distance (dPV), 6. predorsal distance (dPD), 7. head length
(HL), 8. V-A distance (V-A), 9. caudal peduncle length (LPC), 10. maximum body
height (MBH), 11. minimum body height (mbH), 12. maximum body width (MbW),
13. minimum body width (mbW), 14. length of A (lA), 15. height of A (hA), 16.
length of D (lD), 17. height of D (hD), 18. prepectoral distance (dPP), 19. length of
V (lV), 20. preorbital distance (prOd), 21. postorbital distance (POd), 22.
interorbital distance (iOd), 23. eye diameter horizontal (Edh), 24. head height
(HH).
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Table 1. Mean and standard deviation of measured traditional plastic characters of common carp.
Končanica
Draganići
Grudnjak
Našice
(n = 109)
(n = 116)
(n = 101)
(n = 110)
TL
121.5  2.5 a
121.5  2.6 a
122.2  4.2 a
122.2  4.8 a
FL
109.4  1.0a
109.8  1.0a
109.5  1.0a
109.8  3.0a
Characters
In % of standard length
LPC
18.7 
dPA
75.1  2.9bc
1.7 a
17.0 
2.6b
76.4  2.8 a
3.4 a
18.6 
18.6  3.0 a
75.5  3.0ab
74.4  2.3c
lA
6.3  2.3b
6.6  1.1ab
5.9  1.7b
7.0  2.7a
lV
3.7  0.6 a
3.8  1.8 a
3.6  0.8 a
3.9  0.9 a
dPV
46.0  2.0 b
47.8  3.5 a
46.0  3.7 b
45.7  2.5 b
HL
25.7 
27.6 
26.9 
1.6b
26.0  1.7c
lD
37.4  1.6ab
37.8  4.7a
36.3  2.6b
37.6  3.1a
dPD
43.5  1.9 ab
44.4  4.6 a
44.4  2.0 a
43.1  2.5 b
V-A
25.3  2.9 ab
24.8  3.3 b
25.9  3.5 a
24.8  2.5 ab
dPP
25.1 
27.7 
25.9 
2.5 b
25.2  2.1 b
HH
22.4  1.3b
24.6  1.5a
22.4  2.3b
21.4  2.3c
MBH
42.1  2.7 b
43.9  2.8 a
42.1  3.7 b
42.4  3.9 b
hD
13.4  1.4 b
13.6  1.8 b
13.1  1.7 b
14.4  2.2 a
mbH
15.0 
15.0 
15.1 
1.2 a
15.0  1.0 a
hA
12.0  1.4 c
12.5  1.6 c
13.4  2.4 b
14.9  2.8 a
MbW
20.2  1.3 b
20.3  1.3 b
19.7  1.7 b
20.9  2.3 a
mbW
5.7  0.6 b
1.7c
1.8 b
0.9 a
1.7a
2.8 a
0.8 a
6.3  0.7 ab
6.3  0.9 ab
6.7  4.8 a
In % of head length
POd
53.9  2.4 b
53.9  2.3 b
54.0  3.6ab
55.0  3.6 a
prOd
26.2 
26.5 
26.6 
24.5  3.0b
HH
87.1  6.0a
89.1  6.0a
83.4  9.0b
82.6  10.0b
iOd
47.7  3.0b
48.0  3.0b
48.3  4.0b
50.0  4.0a
Edh
19.9  2.1 ab
19.6  2.5 ab
19.4  2.7 b
20.4  3.2 a
3.0a
3.0a
3.0a
Means in the same row with different superscript letters are significantly different (P<0.05).
Table 2. Mean and standard deviation of measured meristic characters of common carp.
Končanica
Draganići
Grudnjak
Našice
(n = 109)
(n = 116)
(n = 101)
(n = 110)
2.982  0.23a
2.957  0.33a
2.980  0.14a
2.936  0.39a
20.697  1.42b
21.353  1.30a
20.198  1.46b
20.355  1.91b
No. of unforked rays in A
2.000  0.00a
1.991  0.09a
2.010  0.17a
2.027  0.16a
No. of forked rays in A
5.835  0.42a.b
5.862  0.37a
5.723  0.49a.b
5.700  0.48b
Characters
No. of unforked rays in D
No. of forked rays in D
No. of forked rays in P
No. of forked rays in V
No. of gill rakers
15.367 
0.72a.b
15.026 
0.79b
15.287 
1.17b
15.645  1.27a
8.761  0.53a
8.784  0.52a
8.792  0.59a
8.855  0.49a
30.415  1.89b
30.643  1.77b
30.074  2.08b
31.594  1.52a
Means in the same row with different superscript letters are significantly different (P<0.05).
Fig. 1. Truss network of distance measures applied to the common carp.
Morphological landmarks are numbered and morphometric distances between
landmarks are shown by thin solid lines.
Fig. 2. Dendrogram of cluster analysis on four carp strains based on 24
traditional plastic characters.
Fig. 3. Dendrogram of cluster analysis on four carp strains based on 7
meristic characters.
Fig. 4. Dendrogram of cluster analysis on four carp strains based on 30 truss
network distances.