The Red-legged Cormorant is classified as Near Threatened by BirdLife International (2008). In Chile and Argentina this species is considered "vulnerable" (Collar et al. 1994, Gandini and Frere 1995, Frere et al. 2004, Frere et al. 2005).
In the Pacific coast, El Niño/Southern Oscillation (ENSO) events and human pressure in coastal areas had an important effect on the abundance and breeding distribution of Red-legged Cormorants (Zavalaga et al. 2002, Frere et al. 2004).
Effects of human activity on populations
Red-legged Cormorants in Chile are threatened by diverse human activities related to coastal development. In some regions, Red-legged Cormorants are hunted by fishermen as well as by seafood-and algae-gatherers. Incidental capture in artisanal fishing nets has been reported in central Chile, but is unlikely to be an important cause of mortality because most fisheries are for shellfish (Frere et al. 2004).
In Peru, competition for food with shellfish extraction could be one of the main factors affecting the Red-legged Cormorant population. High levels of shellfish and kelp extraction could affect trophic relationships on the inter-tidal and benthic community, reducing the availability of preys to the cormorants.
In Argentina, there are no estimates of mortality associated with human activities. However, about 93% of the Argentinean population breeds near coastal cities, making the nests vulnerable to predation by Kelp Gulls (Larus dominicanus).