During the second quarter of the nineteenth century, an argument raged about the identity of a small freshwater fish: was the parr a distinct species, or merely the young of the salmon? This “Parr Controversy” concerned both fishermen and ichthyologists. A central protagonist in the controversy was a man of ambiguous social and scientific status: a gamekeeper from Scotland named John Shaw. This paper examines Shaw’s heterogeneous practices and the reception of his claims by naturalists as he struggled to find a footing on the “gradient of attributed competence” (Rudwick 1985). The case demonstrates the context-specific nature of expert-lay boundaries and identities and explores a range of material and linguistic resources available for negotiating them. Arguing for a view of Shaw’s trajectory as simultaneously one of being a “practical man” and of becoming a naturalist, the paper explores both the permeability of social hierarchies in knowledge production and their effective role in the regulation of competency.

Fish biomass, species richness and composition were compared between upland streams draining two contrasting geological units (Pebas and Tsa) in Colombian Amazonia. Because Pebas sediments reportedly show higher levels of base concentrations than Tsa sediments, we expected that the fish communities from the Pebas streams would show highest biomass and species richness, and that the species composition would vary between the two upland systems. Eight forest streams were sampled in four locations, applying four daily sampling events. Tsa soil samples were comparatively sandy, whereas Pebas soil samples tended to be siltier, with higher levels of exchangeable acidity, Ca, Mg and total bases. Conductivity, concentrations of bases (Ca, Mg, K and Na), bicarbonates and temperature showed higher values in Pebas stream-water samples than in Tsa. In total, 7696 fish individuals were captured, belonging to eight orders, 28 families and 122 species. Pebas streams had 1.3 times more species than Tsa streams, and more than twice the total biomass. Species richness and biomass were highly correlated with conductivity and water concentrations of Mg and Na, and biomass alone with dissolved oxygen. Fish species composition differed significantly between the geological units. Species turnover was not related to distance between sampling locations.