Proceedings of the Vertebrate Pest Conference

Since the mid-1980s, there has been a steady rise in the numbers of great cormorants in all Eurasia, and in the number over-wintering annually in Israel. Winter counts in recent years show about 15,000 - 20,000 great cormorants in Israel; they arrive in October and stay until March. Over the years, colonies of over-wintering great cormorants, which can have over 5,000 individuals each, come into conflict at commercial fish farms in Israel, which are in the form of local concentrations of open earthen ponds, in which are grown very high concentrations of food fish, mainly carp, tilapia, grass carp, and mullet. Over the years, many attempts have been made to reduce the negative impact of over-wintering great cormorants on the commercial fish farms in Israel, utilizing lethal and non-lethal methods. Over 50 banding returns from the last 2 decades showed that the great cormorants over-wintering in Israel originated in the area around the northern Black Sea and Sea of Azov, around the Crimean Peninsula in southern Ukraine (about 1400 km or 850 miles due north). This overabundant species causes considerable damage around its nesting sites in Ukraine by interfering with endangered waterbirds, and by conflicting with fishermen. Israel has recently been exploring ways to utilize international cooperation for management of the nesting population in Ukraine, in order to reduce the size of the wintering population in Israel and also to prevent damage to endangered waterbirds in Ukraine. The major instruments are the European Union’s project INTERCAFE (Interdisciplinary Initiative to Reduce Pan-European Cormorant-Fisheries Conflicts: www.intercafeproject.net), and the African-Eurasian Waterbird Agreement (AEWA) under UNEP’s Convention on Migratory Species (CMS): www.unep-aewa.org, as well as other International Environmental Agreements. An experimental program is proposed for reducing the nesting success of the Ukrainian population. A smaller great cormorant population should impact less upon nesting waterbirds in Ukraine and also decrease the intensity of the conflict with both Ukrainian and Israeli fishermen, thereby lessening the extent of lethal control used against great cormorants in both countries. The proposed experimental program includes egg-oiling of ground-nesting birds and hazing tree-nesting birds with green lasers.