摘要：White catfish (Ameiurus catus) is native to the Hudson River and is now coexisting with the recently established channel catfish (Ictalurus punctatus). These species were sampled from four freshwater reaches and four habitat types of the Hudson River estuary to assess whether the two species overlapped in their habitat use, and whether any impact on the native species was evident. Catfishes were sampled in 1998 and 1999 using baited hoop nets (N = 708 net nights). Catch-per-unit-effort (CPUE, number offish per net night; total catch = 368) of white catfish was significantly different among reaches and habitat types; CPUE was greatest in the upstream reach, and in offshore shoal habitat. Channel catfish (total catch = 344) were more abundant in offshore shoal habitats in upriver reaches, but were more abundant in nearshore and tributary mouth habitats in downstream reaches. Individuals of both species were largest upstream. Individual condition (as relative weight, Wr) varied with reach in white catfish, and was low in a downstream reach; in contrast, Wr did not vary among reaches in channel catfish. White catfish grew slowly compared to channel catfish. Relative to populations in other water bodies in North America, Hudson River fishes of both species grew slowly in their first year, but otherwise grew at expected rates. Channel catfish are becoming more abundant in the Hudson River, as white catfish appear to decline. Channel catfish establishment may be facilitated by greater flexibility in habitat use.
