First record of brown bullhead, Ameiurus nebulosus (Lesueur), in the Łyna River drainage basin (northeast Poland)

Abstract

This paper presents the first records of the occurrence of brown bullhead, Ameiurus nebulosus (Lesueur), in the £yna River drainage basin. In February 2010, 77 brown bullhead were collected in Lake Czarne, and one in July 2010 was caught by angling method in Lake D³ugie in Olsztyn (northeast Poland). The specimens collected in Lake Czarne range from 72 to 154 mm total length (TL) and weighed from 3.9 to 36.8 g. Among measurable characters, the greatest variability was noted in head width, preanal distance, and snout length. The least variability in measurable characters was noted with regard to dorsal fin length, eye diameter, and preventral distance. Because of the adverse impact brown bullhead would have on the indigenous ichthyofauna of the £yna drainage basin, its spreading occurrence in this region is an ecological and economic threat. The brown bullhead, Ameiurus nebulosus (Lesueur), is native to eastern and central North America from Nova Scotia and New Brunswick to the Great Lakes region and south to Alabama. It has also been intro- duced throughout the United States (Scott and Crossman 1973). A. nebulosus is found in lakes, ponds, oxbow lakes, reservoirs, canals, and