DISTRIBUTION, RECENT MORTALITIES AND CONSERVATION MEASURES OF CRAYFISH IN HELLENIC FRESH WATERS

Abstract

Freshwater crayfish are found in 20 out of 53 Prefectures of Greece (38%) and they form isolated populations in relatively pristine water bodies. Three indigenous crayfish species (ICS) occur in Greek waters: Astacus astacus , Astacus leptodactylus and Austropotamobius torrentium , as well as one non-indigenous crayfish species (NICS) Pacifastacus leniusculus . Greece represents probably the most southern natural distribution limit for A. astacus and A. torrentium in the world. Concerning NICS, P. leniusculus was imported, at least in two cases, from Sweden and Germany during the early and late 1980’s respectively, in order to replace A. astacus stocks impoverished by human activities. Recently, Cherax quadricarinatus specimens have been seen in a restaurant’s aquarium and pet shop, raising fears about uncontrolled imports of alien pet species. During our 2004-2005 survey, we found that P. leniusculus established not only a thriving population in the artificial Lake Agra (Region of Central Macedonia), but also they co-occur with A. torrentium there. It is also suspected that A. astacus may co-occur there with these two species, as three large male specimens of A. astacus were caught in a creek close to the lake. Concerning A. leptodactylus , there are three sets of preserved samples from the River Evros (state border with Turkey in Thrace today), dated back to the 19th century, but no recent information about occurrence was available. But the accidental catch of six specimens of A. leptodactylus during May 2005 in that river re-documented the occurrence of the species. Finally, a deep-dwelling A. torrentium population with bluish legs was found to live in depths up to 7,800 meters inside the Aggitis Cave in northeastern Greece. There is a lot of work to be done on geographic distribution, population dynamics, genetics, reproduction, nutrition, diseases, and farming of crayfish species in Greece. Moreover, several actions should be undertaken to reform the existing legislation, in order to protect the native species and their habitats.