A New Era for Small Fish Restocking: Restoring Wader Pari Fish Population
National Wader production reached 9,523.98 tons in 2018, far below other species such as Sepat Siam (34,208.18 tons) and Nilem (12,184.56 tons) in the following year (KKP). Meanwhile, Bilih data has been inconsistently reported after 2018, underscoring gaps in monitoring systems.
Wader is immensely popular in Java, with market demand often exceeding sustainable supply. Average annual per capita consumption of freshwater and brackish fish (of which Wader is a key species) is high, around 16.75 kg (SUSENAS, 2016). This shortage is forcing local restaurants to replace Wader with alternatives like baby tilapia, which offers lower nutritional value.
Between 2022 and 2024, local authorities restocked 1,691,346 local fish (including 542,346 Wader) and 195,100 Giant Freshwater Prawn (Udang Galah) across nearly 200 different locations, following a long-standing restocking model.
However, recent ecological assessments in the Belik River, where past restocking occurred, revealed that Wader Pari was not readily detected, while non-native predators (Nila, Red Devil, and Sapu-sapu) and habitat stress (including agricultural and industrial effluent) may be limiting population recovery.
These findings indicate that sustainable population restoration requires a new, science-backed approach, incorporating rigorous pre-restocking assessment and strengthened long-term community protection mechanisms.
From Rigorous Science to Community-Driven Action
Recognising the need for an advanced strategy, GAIN Indonesia collaborated with Gadjah Mada University (UGM) and the National Research and Innovation Agency (BRIN) to implement a new Wader restocking model.
The project kicked off with an extensive stakeholder participation involving key policymakers from the DKP DIY (Department of Marine and Fisheries), BAPERIDA DIY (Regional Development Planning), experts from UGM and BRIN, and representatives from local resource groups like POKWASMAS (community surveillance) and POKDAKAN (fish farmer groups). This multi-stakeholder meeting successfully achieved consensus on the strategic roadmap, established shared ownership, and ensured that local community needs were directly integrated into the program design.
The new restocking model began with a comprehensive, multi-parameter initial assessment designed to pinpoint the most viable locations and understand the specific threats faced by these fish populations. This assessment was far more detailed than previous efforts, incorporating existing fish population measurements, rigorous water quality parameter assessments, evaluations of biological threats such as predators, and advanced molecular techniques, such as environmental DNA (eDNA) assessment and DNA barcoding. This scientific groundwork is crucial because it not only determines the suitability of the restocking locations but also provides an essential baseline for calculating long-term impact. Out of five options assessed, we selected two locations: the Baros River and the Gandok River, as the pilot sites.
The technical scientific groundwork is seamlessly integrated with decisive community action. Discussions were conducted with local residents in Tirtohargo and Bambanglipuro to document the historical presence of yellow rasbora and collaboration for the restocking area conservation. Collaboration with local government and community groups (DKP, Pokwasmas, Kalurahan Tirtohargo, and Kalurahan Bambanglipuro) supported the finalization of the restocking plan and its monitoring.
The actual fish restocking activities were then carefully planned based on the initial assessment results. The first restocking phase was successfully held on 15 September 2025, in the Baros River, Tirtohargo, Bantul, releasing 5,000 Wader Pari. The second restocking phase was completed on 30 October 2025 in the Gandok River, Bambanglipuro, Bantul, also releasing 5,000 Wader Pari.
Initial Ecological Assessment