Natural waters of Chennai threatened by invasive fish species

(Macropodus opercularis belonging to the family Osphronemidae was detected in
Red Hills lake)

C Shivakumar

Chennai:

The fresh water of Chennai and across the country is slowly being
taken over by invasive fish species threatening the aquatic food chain
as the government lacks regulation to regulate the aquarium trade,
according to Zoological Survey of India director K Venkataraman.



Reacting to a query about alien fish species found in the natural
waters of Chennai, Venkataraman said that there is need for the Union
government to set up a separate authority to regulate invasive
species.



It is believed that one-third of aquatic species on the  International
Union for Conservation of Nature Invasive Species Specialist Group’s
list of 100 worst invasive species are from aquarium or ornamental
releases.



According to Journal of Threatened Taxa, over 150 species of
verteberates, invertebrates, plants and microbes (including pathogens)
that have invaded India’s natural ecosystems and have been documented
come from Aquariums and ornamental aquatic culture.



A study in the journal by Marcus Knight published recently states that
a survey conducted last year between April to June on the water bodies
around Chennai, two invasive species Trichopsis vittata and Macropodus
opercularis belonging to the family Osphronemidae were detected in
Chembarambakkam and Red Hills lakes respectively.



The study done by J D Marcus Knight states that Trichopsis vittata is
a native to South East Asia and has established a viable population in
Florida and their extermination is impossible. Similarly, Macropodus
opercularis is also a native to South East Asia and China and has
established non-native populations in Florida, Singapore and Japan,
which are also the hub of ornamental fish trade, similar to Chennai.



Interestingly, Knight also states that it is not only the aquariums
but also the river linking projects which is bringing non native
species into Chennai.



Interestingly, the recording of alien fish species in the state is not
new. Mozambique Tilapia, which was introduced in southern Indian
reservoirs in 1952 to improve reservoir fishery production has
established well in Moyar River in the Mudumalai Wildlife Sanctuary,
Periyar Lake in Periyar Tiger Reserve and Thenmala River.



Venkataraman stresses the need for creating awareness among the
quarantine department, customs as wells as forest department of the
threat to native species by alien species. He says even alien species
of pests are wrecking havoc on the teakwood and rubber wood.





Interestingly, a newsletter of IUCN this year brought to light the
presence of Red-bellied Pranha in Godavari river. The fish was
illegally introduced for aquarium keeping and now is occasionally
found in fisherman catch at Dhawaleshwarm barrage in Rajamundhry. It
is a predatory and aggressive carnivorous fish, it may compete with
native species for food and other resources, which will eventually
lead to the decline or even extermination of many native fishes in the
river system, the newsletter warns.



Interestingly, the government is hardly maintaining any record of
invasive alien species. Knight in his study states that unless
stringent measures are taken to monitor the aquarium fish trade and
the accidental release of exotic species into our waters, man-made
lakes as well as tanks would emerge as breeding grounds for invasive
fish that will eventually wipe out native freshwater fishes.



Customs, quarantine department and other measures to safeguard against
diseases and pests are inadequate to prevent species that threaten
biodiversity from entering a country. Even the IUCN guideline stresses
the need to move away from the older system that deals mainly with
agriculture and human health and focus on preventing the loss of
native biodiversity caused by invasive alien species. Will India act?



Invasive species in Chennai:



Alien fish species

1. Trichopsis vittata

Origin: South East Asia

Discovered: 2014

Found in: Chembarambakkam lake



2. Fish species: Macropodus opercularis

   Origin: South east Asia

   Discovered: 2014

   Found in: Red Hills

3  Species: Giant gourami

   Origin: South east Asia

   Introduced: 1866

   Recordings: Adyar River

4  Species: Tropical American Catfish (Pterygoplichthys multiradiatus)

Origin: Possibly US

Discovered in: Adyar Basin

Threat: Disrupts aquatic food chain

Discovered: Around 2006-2009