[[Genus Sorubim Cuvier]]

Discussion

Burgess (1989: 249) recognized three species of Sorubim: S. lima, S. latirostris, and S. trigonocephalus, and reported S. lima as “occasionally seen” in the aquarium hobby. Herein, and in earlier publications describing species (Littmann et al. 2000; 2001a; 2001b), I conclude that five species of Sorubim can be diagnosed from morphological characters, and that at least three of the species, S. lima, S. elongatus and S. maniradii are syntopic. Sorubim lima and S. elongatus are commonly seen in the aquarium trade. These taxonomic conclusions have significant implications for both the ornamental and commercial fishing industries in South America, especially because catch data have not recognized multiple species and consequently have confused the potential differential impact of ornamental, commercial, and subsistence fishing.

Commercial fishing within South America is severely limited in that several populations are under-fished (see Littmann et al. 2000) and potential harvests are seemingly unlimited. In addition, there is a need to identify harvested fishes (such as Sorubim), which are not as popular as some of the other food fishes more frequently reported on throughout the Amazon region (Colossoma, Brachyplatystoma, and Arapaima). For example, Sorubim cuspicaudus occurred in over 40% of the collections at 29 sampling sites in the Magdalena River floodplain system (Kapetsky et al. 1977). Other authors refer to S. lima as a highly significant component of the fishery in the La Plata system (Quiros & Cuch 1989) as well. Overfishing of popular fish species (e.g., Pseudoplatystoma fasciatum) continues at seemingly alarming rates (see Kapetsky et al. 1977, Littmann et al. 2000). Perhaps in the future, regulations put on fisherman and their harvests may cause a trickle-down effect, forcing them to target less frequently captured species, such as species of Sorubim and other underutilized, fisheries taxa. For this reason, life history and population ecology studies of Sorubim are urgently needed.