Unregulated aquaculture and invasive alien species: a case study of the African Catfish Clarias gariepinus in Vembanad Lake (Ramsar Wetland), Kerala, India

Abstract

Indiscriminate and illegal farming of the African Catfish Clarias gariepinus, in central Kerala has now resulted in the escape and spread of the species into Vembanad Lake, a large brackish water wetland and inland fish diversity hotspot. We collected 17 individuals of C. gariepinus ranging in size from 200 to 750 mm from different locations in the southern sector of the lake during a field survey conducted in 2007. Samples comprised of mature specimens of both sexes indicating their reproductive potential in the study area. The possible impacts of spread of C. gariepinus into natural water bodies of Kerala, especially the Vembanad Lake, and options for their management are discussed.

Rediscovery of the threatened Western Ghats endemic sisorid catfish Glyptothorax poonaensis (Teleostei: Siluriformes: Sisoridae)

“…Although direct evidence is lacking we suspect that at least Clarias gariepinus is a potential threat to the current population of G. poonaensis as it is a voracious predator (Krishnakumar et al 2011). Restricted distribution of the speceis, decline in the extent of occurance, ongoing threats to the habitats and possible threats to the speceis justifies the IUCN Red list threat catagory of this species as Endangered under the criteria B2ab(i,ii,iii,iv) as assessed by Dahanukar (2010).…”

Sighting of Red-breasted Parakeet Psittacula alexandri (Linnaeus, 1758) (Psittaciformes: Psittaculidae) from Vellayani, Thiruvananthapuram, Kerala, India

“…African Catfish Clarias gariepinus, Red-bellied Piranha Pygocentrus nattereri and South American Suckermouth Armoured Catfish (Pterygoplichthys spp.) have invaded our fresh water ecosystem and depleted populations of our endemic fish species pushing them to extinction (Krishnakumar et al 2011;Singh et al 2014). Lantana camara, Wedelia trilobata, Mimosa diplotricha and other floral invasive species have replaced many native species in (Raghubanshi et al 2005).…”

Conservation of freshwater habitats and fishes in the Western Ghats of India

“…In addition to introductions, some species are believed to have escaped from aquaculture facilities and established themselves in the wild. Established exotic species include the North African catfish Clarias gariepinus (Krishnakumar et al ., ), the Leopard pleco Pterygoplichthys gibbiceps , Amazon sailfin catfish Pterygoplichthys pardalis (often incorrectly identified in the literature as Orinoco sailfin catfish Pterygoplichthys multiradiatus ), cichlids of the genera Cichlasoma and Hemichromis , and the large Pirapatinga Colossoma brachypomum (Krishnakumar et al ., ; Knight, ). These exotic species are adaptable and affect populations of indigenous fish via direct competition for resources, predation and habitat modification.…”