The invasive Ameiurus nebulosus (Lesueur, 1819) as a permanent part of the fish fauna in selected reservoirs in Central Europe: long-term study of three shallow lakes

Abstract

The invasive brown bullhead ( Ameiurus nebulosus (Lesueur, 1918)) has been present in Europe since the late 19th century, but there is still a lack of reliable information about its distribution in Europe and the condition of its population. A long-term study (from 2000 to 2011) in three shallow lakes in Central Europe (eastern Poland) was carried out to determine the occurrence of the brown bullhead and its participation in the fish community. The brown bullhead was present in almost all the sampling fishing in all the lakes studied (C i " role="presentation"> i i _{i} = 72%-82%). Its mean abundance and share in the fish biomass ranged from 4.2% to 13.6% and from 9.4% to 18.9%, respectively. The relative numbers of the brown bullheads ranged from 6.4 to 9.1 NPUE (ind. net − 1 " role="presentation"> − 1 − 1 ^{-1} 12 h − 1 " role="presentation"> − 1 − 1 ^{-1} ) and relative biomass from 197.9 to 430.2 WPUE (g net − 1 " role="presentation"> − 1 − 1 ^{-1} 12 h − 1 " role="presentation"> − 1 − 1 ^{-1} ). In total, the brown bullheads with a total length from 12 to 20 cm were the most common in the surveyed lakes. The results showed that the brown bullhead, because of the constancy of occurrence and the size class structure of specimens, had stable populations in the selected lakes in Poland.