Iloilo’s milkfish output plunges 81% as fishponds sit idle

ILOILO CITY — Abandoned and underused fishponds, rising production costs, and deteriorating coastal environments are driving the decline of Iloilo province’s aquaculture sector, according to a new discussion paper by researchers at the University of the Philippines Visayas.

The University of the Philippines Center for Integrative and Development Studies published the discussion paper, “Abandoned, Undeveloped, and Underutilized Fishponds: Implications on Aquaculture Productivity and Coastal Biodiversity,” on Wednesday, Oct. 14.

The paper was written by UP Visayas researchers Victor Marco Emmanuel N. Ferriols, Lynn Angelo A. Bonitillo, and Zckie P. Pahila of the Institute of Aquaculture at the College of Fisheries and Ocean Sciences, and James David M. Lopez of the Regional Research Center.

Citing data from the Philippine Statistics Authority, the paper found that milkfish production in Iloilo fell from 14,731.8 metric tons in 2020 to 2,747.25 metric tons in 2023, an 81.3% decline.

The authors said the decline began well before the COVID-19 pandemic, which suggests that supply-chain and mobility disruptions aggravated existing problems rather than fully explaining the sector’s long-term downturn.

Milkfish is among the most widely farmed fish in the Philippines, and brackishwater ponds are its traditional production system.

Iloilo’s dependence on brackishwater fishponds makes the decline particularly significant.

The study found that nearly all of the province’s milkfish production came from these ponds, while alternative systems such as marine cages and pens contributed less than 1% of output in the years examined.

The Philippine Statistics Authority’s Fisheries Statistics Division reported in February 2025 that Iloilo’s total fisheries production fell by 41.1% in the first quarter of 2024 from the same period in 2023.

Aquaculture output declined by 29.1%, while production from brackishwater fishponds dropped by 41.9%.

Multiple pressures on fishponds

The study identified environmental degradation, extreme weather, rising operating costs, market competition, and governance gaps as interconnected factors behind the growing number of abandoned, undeveloped, and underutilized, or AUU, fishponds.

Many ponds were developed on former mangrove areas with acid sulfate soils.

The researchers said prolonged use, inadequate pond preparation, and accumulated organic matter can worsen water quality, create harmful conditions for cultured fish, and increase vulnerability to disease.

Typhoons, storm surges, flooding, and extreme heat can also damage pond dikes, disrupt water management, and cause fish stocks to escape.

Heat events may further affect the growth of natural food in ponds, reducing their suitability for aquaculture.

Fishpond operators also face higher costs for feeds, fry, fuel, and labor, alongside fluctuating selling prices.

During stakeholder discussions cited in the paper, some milkfish operators pointed to competition from cheaper supplies brought into Iloilo from provinces such as Pangasinan, Pampanga, and Bulacan.

Weak enforcement of government-issued fishpond lease agreements has compounded the problem, the authors said.

“Many fishponds in the Philippines are operated under fishpond lease agreements (FLAs) issued by the government. However, enforcement of FLA conditions, particularly those related to productivity and proper use, has historically been weak,” the paper said.

“This has led to compounding factors such as idle or underperforming fishponds often remaining under lease for extended periods, limited incentives or mechanisms for the rehabilitation or reallocation of near-expiring FLAs, and policy decisions that are constrained by outdated or incomplete data on actual pond utilization,” the authors added.

Abandoned ponds offer restoration potential

The researchers said the decline also presents an opportunity to restore coastal ecosystems, particularly mangroves that were cleared to make way for fishponds.

Fishpond expansion has long been cited as a leading cause of mangrove loss in the Philippines.

Studies cited in the paper indicate that as much as 95% of Iloilo’s original mangrove cover was converted into aquaculture areas.

In Leganes, north of Iloilo City, the researchers estimated that 25% to 35% of an area once dedicated to brackishwater fishponds had either been converted for industrial use or experienced substantial mangrove regrowth, based on historical satellite imagery.

The paper cited the Leganes Integrated Katunggan Ecopark as an example of how abandoned ponds can be restored through community-based mangrove rehabilitation, with potential benefits for coastal protection, biodiversity, and ecotourism.

The paper also documented natural mangrove regeneration in portions of the former UP Visayas Brackishwater Aquaculture Center in Leganes.

Satellite imagery from 2021 to 2024 indicated an estimated 60% to 70% increase in mangrove cover over three years.

Preliminary field surveys in the abandoned ponds identified five mangrove species and one beach forest tree species.

Fish traps also caught 11 fish species and nine crustacean species, including several with commercial or subsistence value.

The study noted that the abandonment of fishponds built on cleared mangroves has created conditions for ecosystem recovery.

“While the conversion of mangroves to fishponds represents a major source of ecological degradation, the subsequent abandonment of these ponds has created conditions that are conducive to ecosystem recovery,” the paper stated.

“AUU fishponds, despite their degraded origins, often retain key environmental characteristics that allow for the reestablishment of mangrove vegetation. In many cases, abandoned fishponds exhibit reduced anthropogenic disturbance, allowing natural processes to resume,” the authors added.

“Through the reversion of AUU fishponds back to mangrove ecosystems, the restoration of ecosystem services of such areas can also be enhanced. Restored mangrove stands in AUU fishponds have been linked, directly or indirectly, to fisheries productivity and biodiversity, coastal protection, and climate resilience,” the authors stated further in the paper.

Researchers urge integrated management

The authors recommended a three-pronged approach: (1) rehabilitating fishponds that remain viable; (2) redirecting nonviable or environmentally degraded ponds toward ecological restoration; and (3) promoting integrated systems such as aquasilviculture, which combines aquaculture with mangrove habitats.

The authors also called for stronger monitoring and enforcement of fishpond lease agreements, better production and spatial data, and closer coordination among fisheries and environmental agencies.

The paper cautioned that fishponds should not be judged solely by whether they are actively producing fish.

Ecological recovery of idle ponds may also support nearby fisheries by restoring mangrove habitats that serve as breeding and nursery areas for aquatic species.