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Noble crayfish is an endangered species. However, at the same time it is an appreciated object of fishery and consumption in Northern Europe. Aquaculture could solve this controversy. Several crayfish farms have been established in Estonia too. They intend to produce crayfish both for consumption and for stocking into the nature to support the wild populations. To perform the crayfish farming into profitable branch of aquaculture and enhance and protect the natural resources of crayfish, several issues of farming technology have to be solved. This project is focused on two topics: 1. Estimation of the results of different reproduction technologies. Survival, growth and sex ratio of juveniles hatched from separated from females eggs in artificial hatching system will be compared with the results of incubation of eggs under females. The genetic background (origin, coloration, DNA markers) of broodstock will be analysed and taken into account. The database of stocked water bodies will be created and effect of size and origin of stocked crayfish on the production and success of restoration of crayfish stocks will be estimated. 2.Methods for reliable estimation of crayfish stock size in semiextensive ponds and newly established populations in natural waters by testfishing will be developed. For this data about CPUE of testfishing, results of mark-recapture experiments and real crayfish numbers in ponds which can be emptied will be combined. The experiments will be carried out in three Estonian crayfish farms mainly by postgraduate students. |