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INTRODUCTION
Solea impar (Pleuronectiformes-Soleidae) is a sand sole species and it is
common on the South-West coast of Sicily. This species is present in Atlantic and
Mediterranean waters (Tortonese, 1970).
Scarce literature on is available, and it is mainly taxonomic.Solea impar
Solea impar lives in demersal waters on sand and mud at depths of 30-100 m,
this species eats mainly crustaceans (amphipods, mysids shrimps, decapods,
isopods), also polychaete worms and bivalve molluscs. The reproduction is in
spring and summer, with a peak in May (Fishes of the North-eastern Atlantic
and the Mediterranean, 1986).
Knowledge of growth parameters is fundamental for study of population
dynamics.
This poster describes age, growth and spawning seasons for .Solea impar
MATERIALS AND METHODS
Sampling was carried out by artisanal fishery in the port of Selinunte (South-West coast of Sicily) over the
whole year (April 2000 - March 2001). This species was generally caught by trammel nets and gill nets and samples
were taken from commercial landings. This species was recorded over the whole year, but it was really scarce
during Autumn-Winter months, while its abundance was significative between March and August.
Fish total length was recorded to the half centimetre below, weight to the nearest gram. A total of 230 pairs of
sagittae otoliths were collected from specimens of 132-223 mm total length.
CONCLUSIONS
The present study on age and growth in showed a not significant difference between males and females.Solea impar
The literature regarding age and growth for this species is poor, although numerous studies had been developed about inSolea vulgaris
Adriatic Sea and in another species such as: brill ( ), turbot ( ). In these species, formation of opaque andScophtalmus rhombus Psetta maxima
hyaline rings in the otoliths is opposite to another cases. As a matter of fact, wide hyaline ring is formed in summer months and an opaque ring
is formed in the Winter months (C. Froglia and G. F. Giannetti, 1985). On the other hand, the marginal increment in for spring andSolea impar
summer is opaque as generally described in the literature.
As described in the literatura the spawing season is in spring. The maximun GSI values were recorded in April for females. The values of
the GSI showed a not significant difference between males and females.
The relationship between weight and length showed positive allometric growth in both sexes. Females showed a greater allometric
Weight-Length relationship than males. Nevertheless the length increment in female is less than the gain weight (b =3,269 b =3,011) in
female male
according to Abd el Missih, 1984.
Probably the hypothesis developed from De Groot, 1971 about a period of hibernation facilitated through the attitude to the hollow,
observed from Sorbe (1973) in , is reasonable in because it is catch alone in the heat seasons.Solea vulgaris Solea impar
REFERENCES
Abd El Missih , S. (1984) Contribution à la connaissance des Soléidés (Poissonss
Téléostéens) du Golfe du Lion. Systématique, écobiologie. Thése Univ.
Montpellier:
311p.
De Groot, S.J. (1971) On the interrelationship between morphology of the alimentary
tract, food and feeding behaviour in flat-fishes (Pisces Pleuronectiformes). Netherl.
J. Sea Res. (2) : 121-196.5
Deniel, C. (1989) Comparative study of cycles, oogenesis and spawning of two Soleidae,
Solea lascaris Solea impar(Risso, 1810) and (Bennet,1831), on the western coast
of Brittany. J. Fish Biol. , 49-58.35
Froglia, C. & Giannetti G.F. (1985) Remarkes on formation in otoliths of Solea vulgaris
and other flatfishes from the Adriatic sea. FAO Fisheries Report No. 345 (Annex E)
pp. 121-122.
Fishesof the North-Eastern Atlantic and Metiderranean (FNAM)2: 884.
Holden, M.J. & Raitt, D.F.S. 1974. Manual of fisheries science. Part 2. Methods of recourse
investigation and their application. , (Revision 1), pp.127-FAO Fish. Tech. Pap.,115
135.
Sorbe, J.C. (1973) Ecologie et éthiologie alimentaire de l'ichthyofaune chalutable du
plateau continental sud Gascogne. Thése Univ. Aix-Marseille : 125p.
Tortonese, E. (1975) - Osteichthyes.Pesci ossei.Fauna d'Italia vol. XI. Ed. Calderoni.
Age determination and growth of Solea impar (Bennett, 1831)
L. Cannizzaro, G. Bono, S. Vitale, A. Milazzo, P. Rizzo
Istituto di ricerche sulle Risorse Marine e l'Ambiente - Consiglio Nazionale delle Ricerche
via Luigi Vaccara, 61 - 91026 Mazara del Vallo (TP) - Italy
RESULTS
The growth parameters were estimated separately for male and female and
for all specimens together in according to Von Bertalanffy model. Table 1 shows
the estimated growth parameters.
Generally, maximum length was
greater for females than males. The K
values were almost equal for both sexes.
The Von Bertalanffy growth curve fitted to
the age-length data and it is displayed in
Fig. 2. The t absolute values were high,
0
most probably due to the absence of
juveniles individuals smaller than 10 cm.
The GSI values followed a similar pattern
between males and females (Fig. 3). The
GSI value is very small in malse because the
gonad weight is low. In both seasons,
mature females were found, probably, it is
due to a prolonged spawning strategy of
this species and to the capacity of each
mature female to breed twice during the
spawning season (C. Deniel, 1989). The GSI
values are given in table 2.
The Weight-Length relationship was
calculated separately for sexes (Fig .4). The
length and weight ranges were,
respectively, 132-207 mm and 18-76 g for
males, 132-223 mm and 19-119 g for
females. The a and b parameters are
showed in table 3.
Solea impar Linf. K to
Female 234,62 0,29 -2,39
Male 223,81 0,25 -3,14
Female + Male 240,14 0,246 -2,76
Table1 Values of growth parameters of
Soleaimpar from South-West coast of Sicily.
G.S.I. Females Males
March 3.12 0.17
April 4.46 0.18
May 4.39 0.18
June 4.04 0.18
July 1.11 0.07
Table 2 Mean monthly GSI
values in fromSolea impar
South-Westcoast of Sicily.
Solea impar ab
Female 2*10-6 3.269
Male 8*10-6 3,011
Table 3 Parameters a and b of the
Weight-Length relationship of Solea
impar from South-West coast of
Sicily.
Age was read from whole otolith (Fig. 1)
immersed in alcohol and viewed through a
binocular microscope under reflected light and
on a black background. A difference of size
between left and right otoliths were recorded on
some specimens. The otoliths were examined
whole. The interpretation of growth zones
proved fairly difficult, in particularly in the
thickening of older otoliths. Separately, two
readers had examined all the otoliths for three
times. The results were compared and critical
readings discarded.
The Von Bertalanffy equation was used to
calculate the growth parameters.
For each fish, gonads were weighed and a
macroscopic scale was used (Holden and Raitt,
1974) to distinguish the maturation stages
during the spawning period. The macroscopic
identification of mature fish did not present any
significant problem, but the identification of
immature individuals was uncertain. During
the spring-summer season, changes in gonads
development were followed by calculating the
gonado-somatic-index (GSI).
The parameters a and b of the Weight-
Length relationship (W=aL^b) were estimated
by least square method.
(a)
0
50
100
150
200
250
012345678
Age (year)
Length (mm)
Linf.=240.14; K=0.246; t0=-2.76;
0
50
100
150
200
250
012345678
Age (year)
Length (mm)
Linf=234.622; K=0.29; T0=-2.39
(b)
0
50
100
150
200
250
012345678
Age (year)
Length (mm)
Linf=223.81; K=0.25; T0= -3,14
(c)
y = 2E-06x3,2691
R2= 0,9159
0
20
40
60
80
100
120
140
0 50 100 150 200 250
Weight (g)
(a)
y = 8E-06x3,0109
R2= 0,8614
0
20
40
60
80
100
120
140
0 50 100 150 200 250
Length (mm)
Weight (g)
(b)
0%
20%
40%
60%
80%
100%
March April May June July
Stage 5
Stage 4
Stage 3
Stage 2
Stage 1
(a)
0
0,1
0,2
0,3
0,4
0,5
012345678
Months
GSI
(c)
0%
20%
40%
60%
80%
100%
March April May June July
Stage 5
Stage 4
Stage 3
Stage 2
Stage 1
(b)
0
2
4
6
8
10
12
012345678
Months
GSI
(d)
Fig. 2 Growth curve for combined sexes a),
females b) and males c) of Solea impar
Fig. 4 Weight-Length relationship for females
a) and males b) of Solea impar
Fig. 2 Growth curve for combined sexes a),
females b) and males c) of Solea impar
Fig. 3 Monthly aturation stages for males a) and females b); Mean monthly Gonado Somatic Indexm
for males c) and females d) of Solea impar