engleski

The relationship between female size and egg size in stone crayfish Austropotamobius torrentium

The stone crayfish (Austropotamobius torrentium) is the smallest species in Astacidae family and little is known about its ecology, biology and life cycle so the aim of our research was to gather information about it’ s reproduction cycle. In crayfish reproduction, one of the main factors affecting fecundity is egg size. It is known that an increase in egg size causes decrease in fecundity, but it is not known what is the relation between female size and egg size. The research was conducted from October 1998 until April 2000 in streams on Medvednica Mountain. We caught 767 females, from which 92 (11, 99 %) were berried. Berried females were found from the beginning of November till the mid June next year. The total length (from the top of the rostrum till the end of telson) of the smallest female with pleopodal eggs was 5, 4 cm, while the longest one was 9, 29 cm. Diameter of pleopodal eggs varied from 0, 24 mm to 0, 36 mm (mean &plusmn ; SD = 0, 28 &plusmn ; 0, 02) and their number per females from 1 to 104. We found positive correlation between female size and number of eggs (r = 0, 39) and between female size and egg diameter (r = 0, 30), while negative correlation was recorded between number of eggs and their diameter (r = -0, 04). In order to have an accurate fecundity estimate, which is used in the estimation of recruitment, in addition to the relation between egg number and female size, the relation between female size and egg size should also be considered.

Austropotamobius torrentium; Croatia; reproduction; external eggs

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