Feeding habits of the exotic black bullhead Ameiurus melas (Rafinesque) in the Iberian Peninsula: first evidence of direct predation on native fish species
Abstract:The feeding ecology of the exotic invasive black bullhead Ameiurus melas was conducted in the Iberian Peninsula for the first time. Dietary analysis based on the stomach contents of individuals caught in several Iberian basins was carried out as a first step to evaluate its potential threat for the native Iberian ichthyofauna. Aquatic macroinvertebrates (mainly Chironomidae) dominated the black bullhead’s diet in all size-classes and sites, irrespective of natural riverine or artificial lentic habitats. Secondary prey items were responsible for the observed between-sites (microcrustaceans in artificial lentic habitat; oligochaeta and caddisfly larvae in natural riverine habitats) and ontogenetic diet differences (from microcrustaceans to larger prey). These diet variations were also detected in trophic diversity values and feeding strategy plots. Black bullheads consumed plant material, terrestrial prey and co-occurring fish species (native or exotic) and thus they could be considered as generalist or opportunistic, foraging on the most abundant and available prey. There was no positive relationship between black bullhead size (total length) and fish prey size, probably indicating piscivory on dead or dying vulnerable fishes as well as predation on smaller-sized active fishes. The results showed that the black bullhead could negatively affect native Iberian ichthyofauna throughout direct predation and competition. Aspects of potential conservation and management implications of fishes resulting from the undesirable presence of the black bullhead in Iberian water bodies are discussed.
Document Type: Regular Paper
Affiliations: 1: Department of Zoology & Ecology, University of Navarra, P. O. Box 177, E-31080 Pamplona/Iruña, Navarra, Spain 2: Department of Zoology and Physical Anthropology, Faculty of Biology, Complutense University of Madrid, E-28040 Madrid, Spain 3: Department of Biodiversity, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, E-28006 Madrid, Spain 4: Gestión Ambiental Viveros y Repoblaciones de Navarra S.A., c/ Padre Adoain 219 Bajo, E-31015 Pamplona/Iruña, Navarra, Spain
Publication date: July 1, 2008