Economic Leakage in Our Freshwater Waters

Amid Indonesia’s ambitions to bolster food security and the blue economy, there is an undercounted ‘leakage’, namely the economic costs from invasive freshwater species. Plecostomus (Loricariidae), red devil (Amphilophus labiatus/citrinellus), and uncontrolled wild tilapia. This is no longer merely an ecological issue but a hidden fiscal burden, pressuring fishery productivity, damaging infrastructure, and eroding household incomes of fishermen. Global data shows economic losses from invasive species exceeding USD 400 billion per year (IPBES, 2023). Indonesia may not yet have calculated it comprehensively, but local signals are clear. At Cirata Reservoir, for instance, field reports and academic research in recent years indicate the dominance of non-target fish like red devil, which predate on eggs and juveniles of cultured fish and economically valuable catches. Fishermen report a decline in the composition of high-value catches and an increase in ‘bycatch’ that is difficult to market. The problem is not just in the catch yields. Plecostomus are known to damage dykes and banks through digging activities, accelerating erosion and increasing reservoir maintenance costs. On a broader scale, the dominance of invasive species alters trophic structures, disrupting food chains, which ultimately reduces the water body’s carrying capacity for economic commodities like carp, cultured tilapia, or catfish. This means declining productivity, while operational costs (feed, seeds, maintenance) remain the same or even rise. At the micro level, fishermen’s households bear the ‘invisible leakage’. Longer fishing times for smaller yields, increased fuel costs, and lower selling prices because the quality and market preferences do not support invasive species. At the macro level, local governments face rising costs for ecosystem rehabilitation, sedimentation management, and potential water infrastructure damage. This is a classic example of market failure due to negative externalities, where introducers (intentionally or not) do not bear the full social costs incurred. More problematic still, our policies remain reactive. Responses often take the form of sporadic mass captures or invasive fish catching competitions without clear market design. Without stable demand, these interventions quickly lose momentum. We are trapped in ‘programmes’ rather than building sustainable economic mechanisms. This is where the economic approach needs to change, from costs to incentives. First, create a market for invasive species. The government can promote downstream processing by encouraging conversion into fish meal for feed, value-added processed products, and utilisation of collagen and gelatin. Fiscal incentives, such as limited subsidies for processing industries or minimum purchase schemes, can stimulate initial demand. Once prices are formed, fishermen will have economic reasons to consistently suppress invasive populations. Second, implement ‘polluter pays’ instruments in the context of species introduction. Importers, breeders, or parties potentially releasing non-native species must be subject to environmental bond mechanisms. These funds are used for mitigation if invasion occurs. This is not to hinder business, but to ensure risks are not shifted to the public. Third, integrate area-based management through the EAFM (Ecosystem Approach to Fisheries Management) framework. That is, invasive control does not stand alone but becomes part of quota setting, zoning, and aquaculture practices. At strategic reservoirs like Cirata, Saguling, and Jatiluhur, cross-regency/city coordination is essential because fish do not recognise administrative boundaries. Fourth, invest in data-based early detection systems. With advances in artificial intelligence, Indonesia can develop early warning systems utilising imagery, eDNA, and fishermen’s reporting to detect surges in invasive populations before they reach tipping points. Prevention costs are far cheaper than recovery. Fifth, improve seed governance and supply chains. Many invasions originate from aquaculture leaks, such as pond flooding, unintentional releases, or restocking practices without studies. Biosecurity standards must be enforced, including hatchery certification and seed distribution tracking. Finally, we need to change our perspective. Invasive species are not just ‘water pests’, but indicators that our fisheries economy has not fully incorporated environmental costs. As long as these costs remain hidden, economic decisions will continue to be biased. In other words, profitable in the short term, harmful in the long term. If Indonesia is serious about building a blue economy, closing this leakage is a fundamental step. Controlling invasive species means restoring productivity, stabilising fishermen’s incomes, and saving public expenditure. More than that, it is about ensuring that the economic value of our waters does not continue to flow away silently.