Growth of black bullheadAmeiurus melas(Rafinesque, 1820) in Corbara Reservoir (Umbria – Italy)

Abstract

The age and growth of the invasive black bullhead Ameiurus melas (Rafinesque, 1820) were studied in the Corbara Reservoir, an artificial lake located on the River Tiber in central Italy. The results of the research revealed that the population was made up of eight cohorts, the oldest specimens being spawned in 1999. The sex ratio appears to be balanced, although females predominate in the younger cohorts, while the percentage of males increases among older specimens. The differences between sexes in the slope of the length-weight relationship were not statistically significant; the slope for the whole sample (b = 3.055) was significantly greater than 3, indicating an allometric growth pattern of the black bullhead. There were no significant differences in mean back-calculated lengths at age between the sexes. Analysis of Lee's phenomenon revealed the existence of differential mortality among younger individuals (1 and 2 years old) that favours larger individuals. The Von Bertalanffy growth function was TL t = 35.69 {1 -exp[-0.18 (t + 0.27)]}. The specimens caught displayed mean relative weight (W r ) values distinctly below 100 at all ages, while no significant difference emerged between the sexes with regard to condition. RÉSUMÉCroissance du poisson-chat Ameiurus melas (Rafinesque, 1820) dans le Lac Corbara (Ombrie -Italie) L'âge et la croissance du poisson-chat invasif Ameiurus melas (Rafinesque, 1820) ont été étudiés dans le Lac Corbara, un lac artificiel situé le long du cours du fleuve Tevere, en Italie centrale. Les résultats de la recherche ont révélé que la population était composée de huit classes d'âges, les spécimens les plus âgés provenant de la fraie de 1999. Le sex-ratio semble être équilibré, bien que les femelles prédomi-nent dans les classes d'âges plus jeunes, tandis que le pourcentage de mâles augmente parmi les spécimens plus âgés. Les différences entre les sexes en matière de pente du rapport longueur-poids n'étaient pas significatives ; la pente de tout l'échantillon (b = 3.055) était significativement supérieure à 3, indiquant que le poisson-chat a un modèle de croissance allométrique. Aucune différence significative n'a été constatée entre les longueurs rétromesurées moyennes des différents sexes au même âge. L'analyse du phénomène de Lee a révélé l'existence d'une

Boom‐bust like dynamics of invasive black bullhead (Ameiurus melas) in Lake Sava (Serbia)

“…The estimated upper TL limit (9 cm) for YOY observed in Sava Lake was in accordance with the results of Pedicillo et al. (), whereas Cucherousset, Paillisson & Carpenter () and Cucherousset, Paillisson, Carpenter, Eybert et al. () reported a threshold value of 7 cm TL.…”

“…This suggests good recruitment and a rapid recovery of the black bullhead population within the timeframe of a single year. The estimated upper TL limit (9 cm) for YOY observed in Sava Lake was in accordance with the results of Pedicillo et al (2008), whereas and Cucherousset, Paillisson, Carpenter, Eybert et al (2006) reported a threshold value of 7 cm TL. By autumn of 2012, a high number of these YOY had achieved 11-12 cm TL.…”

“…Whereas estimated CPUE for Lake Sava black bullhead fluctuated during the summer and autumn of 2009, 2010 and 2012, there was a significant and uniform decline in CPUE over 2011. Data on CPUE reported for other water bodies, such as the Corbara Reservoir in Italy (Pedicillo et al., ) and native populations in North America (Brown, Willis & Blackwell, ; Mork, Bisping, Fisher & Quist, ; Phelps, Ward, Paukert, Chipps & Willis, ) cannot be compared directly with the results from Lake Sava due to the different sampling methodologies used.…”

“…Reservoir in Italy (Pedicillo et al, 2008) and native populations in North America (Brown, Willis & Blackwell, 1999;Mork, Bisping, Fisher & Quist, 2009;Phelps, Ward, Paukert, Chipps & Willis, 2005) cannot be compared directly with the results from Lake Sava due to the different sampling methodologies used.…”

Risk assessment of non-native fishes in the catchment of the largest Central-European shallow lake (Lake Balaton, Hungary)

“…pollution, low dissolved oxygen levels), this nest-guarding species is omnivorous and aggressive (Braig and Johnson 2003;Novomenská and Kováč 2009). Black bullhead was first reported in Europe, in France, in 1871, where it was imported for aquaculture (Coucherousset et al 2006), and it has since expanded its invasive range to become the most widespread North American ictalurid catfish of Europe (Pedicillo et al 2008). The species' expansion has been human mediated and fast in some cases (e.g.…”