Naturalization of Channel Catfish in the Country of Georgia

摘要

The channel catfish Ictalurus punctatus was first introduced from the United States to the Soviet Union in 1972-1979. From the Krasnodar region of Russia, it was introduced into Georgia during 1976-1978. Ecological studies of channel catfish were initiated along with the naturalization of this new species. Channel catfish were initially reproduced and reared in aquaculture ponds, and offspring from these ponds were used to stock natural water bodies, in particular lakes, where natural populations were formed. The climatic conditions of Georgia are close to the natural habitat of channel catfish. The number of days with water temperature higher than 20°C is about 120-140, and the accumulated heat reaches up to 2,400-2,792 degrees/d. They were also introduced into Lake Paliastomi (open marine lagoon) where the salinity fluctuates up to 8-14%o. These fish were caught in areas with salinity up to 14%o and were often encountered in waters of 4-5%o salinity or greater. Channel catfish grew well in the low-lying warm water bodies: they reached, on average, 19 g at age 1, 310 g at age 2,1,300 g at age 3,2,900 g at age 4, and 4,600 g at age 5. The fish became sexually mature in 3 years. Spawning occurred from May to June, when water temperature reached 24°C or higher. Channel catfish fed on a variety of insects, crustaceans, other bottom-dwelling arthropods, and fishes, especially crucian carp Carassius carassius, which is a strong competitor and is widely spread in the local water bodies. Channel catfish were considered a valuable introduction because they grew well, were adaptable to a wide range of conditions, were highly palatable, and provided important recreational sport fisheries, commercial fisheries, and aquaculture industries. There was concern that channel catfish were being overharvested, and consequently, in 2005, Georgia passed a bill that provided for more restrictive fishing regulations to protect this species from overharvest. The role of society and private entrepreneurs in the protection of channel catfish and regulation of its fisheries is important.