New Delhi, 2014.10.15 (Neetu Chandra Sharma, India Today): Human activities have wiped out the native fish species of the Yamuna and alien fish species are now dominating the 950-km stretch of the river and affecting yields, according to a new study by the National Bureau of Fish Genetic Resources.
The “deliberate or accidental introduction” of the alien species was identified as a key component of the human induced biodiversity crisis that is harming native species and disturbing the ecosystem processes. The greater the incidence of introduction of alien fish species in a region, the higher the probability that some of them become invasive and cause ecological or economic damage, said the study done by the Exotic Fish Germplasm Section of the Fish Health Management Division.
The entire stretch of the Yamuna is used for human activities, including fisheries through which the state department earns substantial revenue by leasing out stretches of the Yamuna to fishermen’s societies.
The data was gathered from 15 landing sites covering major cities along the river. The data was generated every quarter from May 2011 to March 2013.
The local fish species were grouped as Indian major carps (Catla catla, Labeo rohita and Cirrhinus mrigala) among others (see box). The river showed a blend of local and exotic species throughout the year.
However, there was a predominance of alien invasive fishes at most sampling locations. The alien invasive fish species were identified as Cyprinus carpio Var. communis, C. carpio Var specularis among others (see box).
A team of scientists – Atul K. Singh, Abubakar Ansari, Sharad C. Srivastava, Pankaj Verma and A. K. Pathak – collected data from the river that showed that 63 fish species present in its waters belonged to eight orders, 18 families, 39 genus and 63 species.
Of the total of 63 recorded species, 53 were identified as local and 10 as alien invasive species. “The main reasons attributable to the decline in fishes are habitat destruction and fragmentation, water abstraction, industries and increased incidences of alien invasive species in particular,” the bureau said in its report.