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SCALE CHARACTERISTICS OF THE Leuciscus illyricus, Hechel and Kner 1858 OF THE RIVER CETINA
Josip Popović
; Gradski sekretarijat za poljoprivredu i šumarstvo, Grad Zagreb
Sažetak
Investigations of scale characteristics of endemic Leuciscus illyricus of the river Cetina were carried out on a sample of fish of both sexes, 0+ to 8+ months old having a standard average length of 115-312 mm.
The scale shape (F) in the average range of 115-259 mm, shows its greater length growth rate which is followed by a general growth trend of fish body length. For the average size of 290 mm, the scale shape is F - 10/10, which gives the scales a completely cycloid shape. From a standard length greater than 295 mm, the scales grow slower in length which results in an increase in tis diagonal diameter.
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An indicator of the covering scale Kd, to the standard average length of 259 mm is 0.49. With an increase in av the values of Kd decrease, so that the average range is 295-312 mm, Kd = 0.35.
Using the method of Vukovic (1958) types of spawning rings were investigated which appeared in the Leuciscus illyricus. At 3+ to 5+, an intercalaran type (B) appears in mid September. In older ones, there is a decreased intensity of length growth rate, with an earlier maturing of reproductive products and the occurence of spawing rings very close to the winter, the so-called adjunct posthiberal of the Cb type. The formula for spawning rings for the Leuciscus illyricus is defined as Bcb. The first spawning rings occur in males at 1+, and in females at 2+ and only in individuals with a longer body length than average for its size.
Determination of the correction factor with which we correct the real body lenght in the analysis of the length growth rate of fish in the previous years, was carried out through the ventrodiagonal radius relation of the scale (D=and the standard body length of the fish (av). For the average range of 30-320 mm, the following formula can be used:
Dm m = 0.43 (av) x - 2.378 E - 0.5 (av) 2 - 0.062
The estimated standard length (av), that is the correction factor, is when the first occurence of the scale is 15 mm a D = 0.04 mm.
The total number of radail canals of scales is found within a wide interval of from 25-61, which in a great depends on the influence of the environment and their number need not be taken as characteristics to this species, as is mentioned in fish systematics (Vukovic, Ivanovic, 1971).
Based on the obtained data certain rules in dynamics and morphological¬meristic characteristics were determined of the Leuciscus illyricus scales. With this it is possible to reconstruct the reaction of the fish organism in certain ecological conditions and certain growth periods.
Ključne riječi
scale; shape; Leuciscus illyricus
Hrčak ID:
70471
URI
Datum izdavanja:
29.12.1994.
Posjeta: 1.278 *