A CASE STUDY IN ANDAMANS

• Chital (spotted deer) were brought to Ross Island by the British in the early 20th century.
• Ross Island (officially known as the Netaji Subhash Chandra Bose Island) is very small (0.3 sq km) and lacks natural predators or competitors for chital.
• Chital are adept swimmers, which facilitated their spread across the Andaman Islands.
• To manage the increasing chital population, the administration sought help from the Wildlife Institute of India.
• Studies over the past two decades have highlighted the negative effects of chital on native flora and fauna.
• This situation has brought attention to the broader issue of invasive species and their threat to endemic ecosystems.

WHAT ARE INVASIVE ALIEN SPECIES?

• Definition of Invasive Alien Species (IAS) according to the CBD:
  • IAS are species whose introduction and spread outside their natural distribution threaten biological diversity.
  • They can include animals, plants, fungi, and microorganisms, impacting various ecosystems.
• Characteristics of IAS according to the CBD:
  • “Arrive, survive, and thrive” summarizes their traits.
  • They are introduced through natural or human means, survive on native resources, reproduce rapidly, and outcompete native species.
• Legal definition of IAS in India under the Wildlife Protection Act, 1972 (amended in 2022):
  • IAS are non-native species whose introduction or spread may harm wildlife or its habitat.
  • This definition doesn’t cover species within India that may be invasive regionally, like chital in the Andamans.

WHAT ARE SOME EXAMPLES OF INVASIVE WILDLIFE IN INDIA?

• Dominant species of fish – African catfish, Nile tilapia, red-bellied piranha, and alligator gar, and turtle species such as the red-eared slider

RED-EARED SLIDER

• Species of Turtle – native to North America
• Favorite among India’s exotic pet owners + many have been abandoned in local water bodies
• Edges out local freshwater species – fast rates of reproduction + competition for food
• Specimens are routinely seized by authorities as a measure to thwart illegal trade of wildlife (Recently, Customs Air Intelligence Unit seized 6,850 live red-eared sliders from two passengers at the Trichy International Airport)

FISHES

• Introduction of fish species for aquariums due to high demand.
• African catfish was imported from Bangladesh for aquaculture purposes.
• The species C gariepinus has been reported in various inland systems of India, including major rivers like Ganga, Yamuna, Sutlej, Godavari, Periyar River, and lakes like Vembanad Lake, as per a 2019 study by the National Biodiversity Authority

HOW DO IAS IMPACT NATIVE FLORA AND FAUNA?

• Invasive alien species disrupt the food chain and ecosystem balance.
• They can dominate ecosystems without competition, leading to significant impacts.
• Example: African catfish preys on waterfowl and migratory birds in Keoladeo Park, Rajasthan, a UNESCO World Heritage site.
• Chital in Andamans hinder native vegetation regeneration by consuming seeds and seedlings

WHAT ARE IAS’ ECONOMIC IMPACT?

• The Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) reported around 37,000 established alien species worldwide, with approximately 200 new species introduced annually.
• IAS contribute to a global economic cost exceeding $423 billion annually as of 2019, mainly due to damage inflicted on natural ecosystems.
• Example: The cotton mealy bug, an invasive species from North America, has severely impacted cotton crops in the Deccan region, causing significant yield losses as per India’s National Biodiversity Action Plan of 2019.