We present the ecological functions of cormorants and estimate the economic value of these functions to artisanal fishermen, as a valuation exercise for Neotropic Cormorants at Los Olivitos Estuary, Lake Maracaibo, Venezuela. Ecological functions were based on estimating the abundance, distribution and diet of cormorants; economic values were attached to a selection of goods, services and attributes. Based on available information, we selected four ecological–economic functions of cormorants: harvesting for food; contributors to fish diversity; indicators of fish schools; and contributors to fish biomass, due to guano production. Cormorants consumed nine commercial fish species. Mean consumption was 225 g/ind/day. All ecological–economic functions were positive except for the role as contributors to fish biomass. Total value of the cormorant population to fishermen was $5,429,703/year. Unlike many studies, our results show that Neotropic Cormorants have a negligible impact on artisanal fisheries. We emphasize the importance of these results for management policies.