engleski

Seasonal changes of the hepatosomatic indices in the noble crayfish (Astacus astacus) and the stone crayfish (Austropotamobius torrentium)

A comparative study was conducted on two autochthon species of Astacidae in Croatia, the noble crayfish, Astacus astacus (Linne, 1758) and the stone crayfish, Austropotamobius torrentium (Schrank, 1803). Hepatosomatic indices (wet and dry hepatosomatic index) and hepatopancreas moisture content (HM) are considered useful to describe the physiological condition of wild crayfish populations. Noble crayfish were trapped from the Vukovina gravel pit and the stone crayfish from the Kraljevec Stream. Each month five to ten animals were sacrificed and dissected. Hepatopancreases were weighed, dryed for 24 hours on 80oC and weighed again. Seasonal changes of the hepatosomatic indices and HM in two populations were observed.Hepatopancreas mean weight varied from 2% of wet body weight after winter starvation period to 6% during spring and summer period. HM was higher during autumn and winter periode (70-80%) and lower during spring and summer periode (50-60%). Wet hepatosomatic indeks (Hiwet) was between 4, 0 and 6, 5% and changed from month to month, while dry hepatosomatic indeks (Hidry) varied between 0, 6 and 2, 8%. All investigated parameters indicated nutritional status of the animals and differences between two species were evident.

noble crayfish; stone crayfish; hepatosomatic indices; Croatia

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