Introduced aquatic species for inland aquaculture: Boon or bane?
Boosting fisheries and aquaculture production is the primary driver for the introduction of aquatic species to inland water bodies. Various records show that a total of 155 fish species, 24 mollusks, 13 crustaceans, 6 reptiles, 1 amphibian, and 6 seaweed species are introduced aquatic species (IAS) in Southeast Asia. The Philippines ranks the highest in terms of number of introductions with 115 different species, followed by Singapore with 95. The bulk of these introductions are freshwater fishes, dominated by representatives from the family Cichlidae (33 species) and Cyprinidae (40 species). Nonetheless, IAS continues to provide tremendous gains in terms of increased production and consequent economic gains for Southeast Asian countries, contributing from 9 to almost 99% of freshwater aquaculture production in the region based on average 2010-2014 data. Despite these, there are well known adverse impacts of species introductions such as their effects on biodiversity, and possible introduction also of new pathogens and diseases. In addition, some of these IAS become well adapted to their new environment to the extent of being classified as invasive. Measures to address these adverse impacts of species introductions in inland waters should be undertaken through careful crafting and implementation of regulations on species introductions; conduct of science-based risk assessment prior to introduction; shift in focus towards culture of commercially important native species; and balancing ecological risk and economic gains through valuation of ecosystem goods and services of inland water bodies.