(l.) from lakes morzyczko and pe£cz (nw poland)

1Zoologica
59
VENDACE-C.-ALBULA-FROM-LAKE-MORZYCZKO-AND-PE£CZ
Poloniae
(2004) 49/1-4: 159-170
159
AGE, GROWTH AND CONDITION OF VENDACE
COREGONUS ALBULA (L.) FROM LAKES
MORZYCZKO AND PE£CZ (NW POLAND)
P RZEMYS£AW C ZERNIEJEWSKI and R OBERT C ZERNIAWSKI
Department of Fisheries Management in Inland Waters, Agricultural University
of Szczecin, Kazimierza Królewicza 4, 71-550 Szczecin, Poland
Abstract. Comparative biological studies on 110 individuals of vendace from
Lake Morzycko and 104 specimens from Lake Pe³cz, collected in autumn, concerning
individual weight, total length, condition and growth rate, showed some statistically
significant differences in particular biological characters. The vendaces from Lake Pe³cz
had the average individual weight lower by 38%, total length lower by 11.7% and were
clearly in a worse condition. The results of back-calculations and parameters of von
Bertalanffy's equation reveal distinct disproportions in the total length in particular
age groups. Slower growth rate in terms of both length and weight was found in the
sample from Lake Pe³cz. Lower values of the condition coefficient and growth rate
of fish from this area resulted probably from worse environmental conditions in this
lake.
INTRODUCTION
Out of the 1594 lakes of Western Pomerania region, vendance inhabits only
43 (CZERNIEJEWSKI and F ILIPIAK , 2001). Lake Pe³cz, situated in the Choszczeñskie
Lake District and Morzycko in the Myœliborskie Lake District, have been considered to be of major economic importance for fisheries and the vendace-type
lake management model is implemenced there; vendace constitutes over 50% of
fish captured. In last years, in spite of stocking, in both lakes a considerable
decrease of vendace captured was recorded, which probably resulted from the
X V I I I C o n g r e s s o f P o l i s h Z o o l o g i c a l S o c i e t y, 1 5 - 1 8 S e p t e m b e r 2 0 0 3 , To r u ñ , P o l a n d
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P.-CZERNIEJEWSKI-and-R.-CZERNIAWSKI
160
progressive eutrophication as well as deteriorated physical and chemical water
conditions. It is evident particularly in Lake Pe³cz, where within 1998-2000 a
severe collapse of commercial catches was noted, in consequence of the complete depletion of oxygen contents in the layer of water at 7 m of depth down
to the bottom, during the summer and autumn period (P IASECKI , 2000). Taking
this phenomenon into consideration, biological studies were carried out, aimed
at estimating the age, condition and growth rate of harvestable part of vendace
population from these lakes.
MATERIAL AND METHODS
Fishes examined were captured during the autumn catches in 2000, performed in lakes Pe³cz (104 individuals) and Morzycko (110). The samples were
collected in the night's time commercial fishing with the gillnets of mesh size 24
mm. The material collected was immediately transported in ice to the labolatory
of the Departament of Fisheries Management in Inland Waters of the University of Agriculture in Szczecin, where all specimens were examined biologically:
total length with the accuracy of 1 mm was established, individual weight (W 1 )
and - so called- the second weight- without entrails (W 2), estimated on the
electronic balance (type AXIS), with the accuracy of 0.1 g. Condition of fish was
estimated on the basis of condition coefficients: Fulton's K and Clark's K c
(R ITTERBUSCH -N AUWERCK , 1995). The first parameter was established according to
the formula:
K=
W1 * 100000
L3
where: W 1- total weight of fish (g); L- total length of fish (mm).
When calculating Clark's coefficient (Kc) in the above formula, the weight
of gutted fish (W 2) was applied instead of total weight (W 1).
The above condition coefficients were calculated for each fish separately,
then their relation to the total length was displayed as a linear function with the
step of length of 10 mm assumed.
The comparison of nutritional status was performed also by estimating the
total length individual weight of fish (W1) relationship, with the aid of exponential function (S ZYPU£A et al., 2001): W=kL n; where W- total weight of fish (g);
L- total length of fish (mm); k, n - constant parameters, calculated based on
empirical datas.
Age of fish and growth rate in terms of length and weight were estimated
based on the scales. The scales were sampled followig B ERNATOWICZ (1952), next
they were cleaned from of mucus in ammonia water and prepared for examination. Age reading as well as measurements of scale radii were performed on their
oral parts, using the computer image analysis system "MultiScan" (the accuracy
of measurements 0.001 mm).
Since the relationship R-L was found to be linear, back calculations were
made in the Rosa-Lee variant, with regard to the standard amounted to 30 mm
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VENDACE-C.-ALBULA-FROM-LAKE-MORZYCZKO-AND-PE£CZ
161
- the length at which in vendace the scales start forming (G RUDNIEWSKI , 1970).
Data obtained with the above method were then used to show a theoretical
growth rate of length and weight of vendace as well as to estimate the parameters of mathematical models of growth, with the aid of von Bertalanffy's equation, 2nd degree polynomial and GL parameters (SZYPU£A et al., 2001).
RESULTS
Out of the total number of 214 individuals from both lakes, fish aged 2 +
predominated (185 specimens- 86.4%). In Lake Pe³cz fish aged 1 + were represented by 23 fish individuals aged 2 + by 78, 3 + by 3. The sample from Lake
Mokrzycko contained 107 individuals aged 2 + , and only 3 aged 3 +. The analysis
of samples with regard to the sex, in both lakes, showed a considerable prevalence of females (85.6% in Pe³cz, and 82.7% in Morzycko). The higher number
of females was observed in particular age groups, as well (Table 1). The mean
total length of vendace studied differed significantly (p < 0.05) between the two
lakes. Despite the selective fishing equipment (gillnets of the same mesh size
- 24 mm), the higher value of this parameter - by 11.7% - was recorded for
specimens from Lake Pe³cz (Table 1). A much greater disproportion between the
samples examined was displayed by mean weight. Fish from Lake Morzycko were
characterised by a higher value of this parameter, when compared to the sample
from Lake Pe³cz (72.81 g and 45.15 g, respectively). A similar tend as in the
whole sample, was observed in particular age groups (Table 1).
A wide range of total length and body weight of the fish studied is
noteworthy. This phenomenon probably results from fact, that in spite of the
material being caught "correctly" in the gillnets, ca 10% of all fishes were
constitutes much bigger individuals to the net with their external body parts.
In the whole material from Lake Morzycko length classes 190.1-200 mm and
200. 1- 210 mm predominated, while in that from Lake Pe³cz - 160.1-170 mm and
190.1-200 mm (Fig. 1). In the particular lakes in the length classes mentioned
above, 87 specimens (79.1%) and 44 (42.3%) were classified jointly.
The differences in average body length and size structure of fish from both
lakes are reflected in the values of indices of nutritional status: condition
coefficient and length/weight relationship. The values of Fulton's (F) and Clark's
(K c ) coefficients for fish Lake Morzycko were by 5.1% and 5.5% higher, respectively. Indirectly, the parameters of total length and individual weigth relationship, point at better condition of fishes from the lake mentioned (Fig. 2).
In both lakes the coefficients K and K c decrease with increasing total
length (Fig. 3); the correlation coefficients are statistically significant at the
level of 0.05.
Table 2 presents total lengths in the particular age groups obtained by
back calculations, as well as values of parameters of 2nd degree polynomial
determining the coefficient of fish growth (GL) in the two lakes. Vendace from
both lakes displayed the highest growth rate in the first year of life (12.05 and
Coefficients of
Sex
Total length (mm)
Body weight (g)
condition
structure
Lake
Age
n
?
Mean
Range
Mean
Fulton’s
Clark’
Mean
Mean
Range
total
19
91
110
200.63
185.60 – 225.00
72.81
54.00 – 91.20
1.18
0.90
1+
-
-
-
-
-
-
-
-
-
2+
19
88
107
200.04
185.80 – 221.75
70.10
54.00 – 89.50
1.18
0.91
3+
-
3
3
221.74
219.23 – 225.00
88.87
86.30 – 91.20
1.18
0.85
15
89
104
177.16
149.02 – 213.85
45.15
21.50 – 85.30
1.12
0.85
1+
3
20
23
156.34
149.02 – 163.49
31.24
21.50 – 39.50
1.16
0.87
2+
11
67
78
181.78
163.78 – 204.22
47.82
26.00 – 80.10
1.08
0.87
3+
1
2
3
212.89
210.59 – 213.89
70.10
61.1 – 85.30
0.94
0.82
?
total
?
L. Pe³cz
P.-CZERNIEJEWSKI-and-R.-CZERNIAWSKI
?
L. Morzycko
162
Table 1
Basic biological data of the vendace from Lake Morzycko and Lake Pe³cz (n- number of individuals)
162
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VENDACE-C.-ALBULA-FROM-LAKE-MORZYCZKO-AND-PE£CZ
163
Table 2
Growth rate of vendace from Lake Morzycko and Lake Pe³cz. Length, backcalculations and values of growth coefficient GL
Length (Tl, mm) in consecutive
years of life
Lake
GL
L1
L2
L3
Morzycko
12.05
18.80
21.50
46.83
Pe³cz
10.16
17.19
19.07
34.58
Table 3
Variation of growth rate in vendace from Polish lakes
Total length (Tl, cm) in consecutive years of life
Author
Lake
l1
l2
l3
l4
l5
l6
Maróz
9.5
13.7
15.8
19.2
-
-
Lutry
10.7
14.6
15.6
-
-
-
Narie
9.5
14.5
16.6
17.1
-
-
Is¹g
11.4
16.7
19.1
21.4
-
-
Gorzyñ
11.2
17.9
23.2
-
-
-
Mastyñski (1978)
Wdzydze
8.0
14.5
19.6
23.1
26.1
28.4
Marsza³ek (1961)
P³êsno
13.2
19.7
23.0
-
-
-
Cieszêcin
9.9
18.1
22.9
25.9
27.4
-
£êtowo
15.8
20.5
22.5
-
-
-
¯erdno
14.9
21.3
24.7
26.7
-
-
Iñsko
13.7
20.5
23.5
26.3
-
-
Morzycko
12.1
18.8
21.5
Pe³cz
-
-
-
10.2
17.2
19.1
Christianus (1995)
Marciak (1970)
This study
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P.-CZERNIEJEWSKI-and-R.-CZERNIAWSKI
164
Number of individuals
60
50
40
Pe³cz Lake
Morzycko Lake
30
20
Total length classes (mm)
10
0
140,1-150
150,1-160
160,1-170
170,1-180
180,1-190
190,1-200
200,1-210
210,1-220
220,1-230
Fig. 1. Distribution of total length (Tl) of vendace from Lake Morzycko and Lake
Pe³cz.
Weight (g)
100
90
80
70
60
50
2.0631
y = 0.0013x
2
R = 0.62
Morzycko Lake
40
30
2.4051
y = 0.0002x
2
R = 0.76
Pe³cz Lake
20
10
Total length (m m)
0
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
Fig. 2. Relationship between the total length (Tl) and weight of vendace from Lake
Morzycko and Lake Pe³cz.
VENDACE-C.-ALBULA-FROM-LAKE-MORZYCZKO-AND-PE£CZ
Condition of fish
165
165
1,4
y = -0.0041x + 2.0493
R2 = 0.906
Fulton's coefficient
1,3
1,2
1,1
1
0,9
0,8
0,7
Condition of fish
0,6
180
y = -0.0042x + 1.7713
R2 = 0.9276
Clark's coefficient
Total lenght (mm)
190
200
210
220
230
1,4
y = -0.0038x + 1.8372
R2 = 0.934
Fulton's coefficient
1,3
1,2
1,1
1
0,9
0,8
0,7
0,6
130
y = -0.0021x + 1.2436
R2 = 0.867
Clark's coefficient
150
Total length (mm)
170
190
210
230
Total lenght (cm)
Fig. 3. Relationship between the condition and total length (Tl) of vendace from
Lake Morzycko (A) and Lake Pe³cz (B).
30
Loo= 24.88cm (Morzycko Lake)
25
20
Loo= 22.56cm (Pe³cz Lake)
15
Pe³cz Lake
Morzycko Lake
10
5
Age of fish (years)
0
0
1
2
3
Fig. 4. Growth rate of vendace from Lake Morzycko and Lake Pe³cz, length, von
Bertalanffy's equation.
166
P.-CZERNIEJEWSKI-and-R.-CZERNIAWSKI
166
120
Woo= 98.56g (Morzycko lake)
Body weight (g)
100
80
Woo= 81.2g (Pe³cz lake)
60
40
Pe³cz Lake
20
Morzycko Lake
Age of fish (years)
0
0
1
2
3
Fig. 5. Growth rate of vendace from Lake Morzycko and Lake Pe³cz, weight, von
Bertalanffy's equation.
10.16 mm, respectively). In subsequent years the length increments were observed decrease slowly (increments are nearly twice smaller, compared to the
values from the preceding year).
The lengths calculated with the Rosa-Lee method, were used to estimate
parameters of mathematical model of growth rate, according to von Bertalanffy's
equation. The models are as follows:
Lake Morzycko : Lt=24,88[1-e -0.666955(1+0.032883)]
Lake Pe³cz: Lt=22,65[1-e -0.623784(1+0.061946)]
It should be stressed that the average absolute difference between empirical data (obtained from back calculations) and theoretical data (from von
Bertalanffy's equation) amounted to 0.25 mm and 0.61 mm, respectively. The
inconsiderable difference indicates a good fit of the mathematical model of
growth rate to the empirical data.
Figs 4 and 5 show curves of length and weight growth as well as key
parameters of von Bertalanffy's equation. Fishes from Lake Morzycko were
characterised by faster growth rate in terms of both length and weight in
particular age groups, as shown by higher total lengths and average individual
weights in the succeeding years of life. It can be visible indirectly in the
differences of the growth coefficient values - GL (Lake Mokrzycko- 46.83 and
Lake Pe³cz 34.58).
The mathematical model of growth in term of weight can be presented as
follows: Lake Morzycko: Wt=98.56[1-e -0.666955(1+0.032883)] 2.0631
Lake Pe³cz:
Wt=81.20[1-e -0.623784(1+0.061946)] 2.4051
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VENDACE-C.-ALBULA-FROM-LAKE-MORZYCZKO-AND-PE£CZ
167
DISCUSSION
Vendace is a pelagic fish of a short life span. Two- and three-year-old
individuals predominate in the catches (BERNATOWICZ et al., 1975), while maximum age recorded in the water bodies of Poland was 9+ (M ARCIAK , 1970). The
age structure of the harvestable part of vendace population from lakes Morzycko
and Pe³cz did not diverge from the data presented above. In both lakes vendace
aged 2 + predominated (97.3% and 75.0%, respectively). The absence of older
specimens (above 3+) in the catches may result from the high selectivity of the
gillnets (of constant mesh size 24 mm) used in the vendace catches. This mesh
size enables a catch of fish of length from 17.8 to 24.2 cm, with the highest
efficiency for 21.0 cm (C IEPIELEWSKI , 1974). However, the samples from the two
lakes differed significantly in the average total length and body weight. This
fact, as well as the relatively high values of these parameters, higher compared
to data given in C IEPIELEWSKI (1974), resulted from the presence of markedly
bigger specimens in the gillnets.
Fish condition is estimated by means of the mathematical formulas or
parameters of the length-weight relationship (LE CREN, 1951; BOLGIER and CONNOLLY,
1989; R ITTERBUSCH -N AUWERCK , 1995). Condition of fish from the two lakes estimated with Fulton's and Clark's coefficients, is within the range of values (1970
given in S ZYPU£A . 1998), W INFIELD et al. (1996), C ZERNIEJEWSKI et al. (2002). The
slight differences in the average values between our own data and these available in the literature, may result from the different period of catches as well as
disregard of the effect of length fish on the results of the analysis. However,
the increase of condition coefficient with the length and age was observed in
pikeperch (S ZYPU£A , 1998), roach (WIÊSKI , 1998) and perch (SZYPU£A and R YBCZYK ,
2001). Our results indicate a relationship between the condition of vendance and
their total length, however along with increase of this second parameter, a
gradual, small decrease of values of Fulton's and Clark's coefficients was
recorded. The second index of fish condition is the length - weight relationship,
which is usually expressed as an exponential function. The value of the exponent of this function for vendace is ca. 3 (C HRISTIANUS , 1995; S ANDLUND , 1992),
which indicates isometric character of growth in this species. In some lakes,
abounding with crustacean plankton, this parameter reaches the value close to
3.5 (WINFIELD et al., 1996), however in lakes where environmental conditions are
unfavorable for vendace, the value of the exponent is below 2.5 (C ZERNIEJEWSKI
et al., 2002). The mean values of "n" parameter of the length-weight relationship
vendace populations examined were low, indicating that that lakes do not support a sufficiently abundant (quantitatively and qualitatively) plankton food for
vendace. Except for some specific environmental conditions, the growth rate of
vendace is influenced by the richness of crustacean plankton (B AUCH , 1961).
Due to a large diversity of habitat conditions in lakes, a high diversity of
vendace growth is recorded (Table 3). Fishes originating from Lake Morzycko
and Lake Pe³cz exhibit higher growth rate when compared to data given in
C HRISTIANUS (1995) for Mazovian lakes: Maróz, Lutry, Narie and Is¹g and similar
168
P.-CZERNIEJEWSKI-and-R.-CZERNIAWSKI
168
to the growth rate of vendace from Pomeranian lakes (M ARCIAK , 1970) as well
as from Lake Gorzyñ of Wielkopolska (MASTYÑSKI, 1978). According to SZCZERBOWSKI
(1978) vendace of the length of 183 mm and weight of 55 g in the second year
of life (l2) has a high growth rate, whereas B ERNATOWICZ et al. (1975) regard the
growth of vendace aged 2 + of over 200 mm length only as good. When analysing
literature data it should be stated that vendace from Lake Morzycko was
characterised by a good growth rate, while in Lake Pe³cz - the growth rate was
average. The low condition and average rate of length and weight growth of
vendace from Lake Pe³cz reflect the unfavourable hydrochemical conditions of
the lake. As shown by P IASECKI (2000) the lack of oxygen deficit in Lake Pe³cz
confines migrations and foraging of vendace to the water layer of thickness of
7 m, which on the one hand limits the feeding grounds, and on the other,
facilitates a parasite infestation and infection with fish diseases. The next step
of our investigationswill be an assessment of health status of vendace from the
two lakes.
WIEK, WZROST I KONDYCJA SIELAWY COREGONUS ALBULA (L.)
Z JEZIORA MORZYCKO I PE£CZ (PÓ£NOCNO-ZACHODNIA POLSKA)
STRESZCZENIE
Sielawy do badañ pochodzi³y z jesiennych po³owów gospodarczych
dokonywanych wontonami o œrednicy oczka 24 mm z zachodniopomorskich jezior:
Pe³cz (104 szt.) i j. Morzycko (110 szt.). Na œwie¿ym, nie mro¿onym materiale
wykonano pomiary d³ugoœci (l.t.), masy jednostkowej (W 1 ), masy ryb po
wypatroszeniu (W 2 ), wykreœlono zale¿noœæ L-W oraz okreœlono kondycjê
(wspó³czynnik Fultona i Clark). Dodatkowo przy pomocy ³usek ustalono wiek
pozyskanych sielaw. Wzrost d³ugoœci analizowano metod¹ odczytów wstecznych
w wariancie Rosy- Lee oraz matematycznym modelem wzrostu von Bertalanffy'ego.
Badania struktury p³ci wykaza³y dominacjê samic zarówno w próbie z j. Pe³cz, jak
i j. Morzycko (odpowiednio 85,5 i 82,7%). Sielawy z tego pierwszego zbiornika
charakteryzowa³y siê mniejszymi wartoœciami d³ugoœci ca³kowitej (œrednia 177,2 mm;
zakres 149,0-213,9 mm) i masy jednostkowej (œrednia 45,15 g; zakres 21,5-85,3 g)
w porównaniu do ryb z j. Morzycko (odpowiednio œrednia 200,6 mm; zakres
185,6-225,0 mm oraz 72,81 g; zakres 54,0-91,2 g). Zale¿noœæ pomiêdzy mas¹
jednostkow¹ a d³ugoœci¹ ca³kowit¹ dla próby z j. Pe³cz wyra¿a³a siê wzorem
Y = 0,0002x 2,4051 , a dla ryb pozyskanych z j. Morzycko Y = 0,0013x 2,0631 .
Równoczeœnie u tej pierwszej grupy sielaw zanotowano ni¿sze o blisko 6%
wspó³czynniki kondycji Fultona i Clark. Z przeprowadzonych analiz wieku wynika,
i¿ w obu grupach pozyskanych ryb stwierdzono wyraŸn¹ dominacjê osobników
w wieku 2+. W próbie z j. Pe³cz udzia³ osobników w wieku 1+ wyniós³ 22,1%,
2+ - 75% a 3+ - 2,9%, natomiast w j. Morzycko sielawy w wieku 2+ stanowi³y
97,3%, a 3+ - 2,7%. Ryby z tego pierwszego zbiornika charakteryzowa³y siê
gorszym tempem wzrostu zarówno d³ugoœci jak i masy. Tempo wzrostu sielaw
z j. Morzycko oceniono jako dobre, natomiast z j. Pe³cz- przeciêtne.
169
VENDACE-C.-ALBULA-FROM-LAKE-MORZYCZKO-AND-PE£CZ
169
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