Abstract

A comparative study was conducted on two autochthonous species of Astacidae in Croatia, the noble crayfish, Astacus astacus (Linné, 1758) and the stone crayfish, Austropotamobius torrentium (Schrank, 1803). Hepatosomatic indices (wet and dry hepatosomatic index) and hepatopancreas moisture content (HM) were measured and used to describe the physiological condition of crayfish populations during an annual cycle. Noble crayfish were trapped from Vukovina gravel pit and the stone crayfish from Kraljevec Stream. Each month five to six animals were sacrificed and dissected. Hepatopancreata were weighed, dried for 24 hours on 80°C and weighed again. Approximately half of each hepatopancreas was prepared for histological analysis. Seasonal changes of hepatosomatic indices and moisture content in crayfish from the two populations were measured. Hepatopancreas moisture content was higher during the reproductive period than during the moulting period. The proportion of hepatopancreas in body weight (Hiwet) was not statistically different between males and females of both species. Changes in proportion of R-, B- and F-cells in tubule epithelium of hepatopacreas during a year cycle were measured. Analysis of variance showed no statistically significant differences in hepatosomatic indices and moisture content of the two species investigated.

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