Large fish disappearing from Taiwan's coasts due to overfishing: NGO

Taipei, June 10 (CNA) Greenpeace Taiwan on Wednesday released research showing that smaller fish are making up an increasing share of Taiwan's inshore and offshore catches, a trend the environmental group said indicates larger fish are becoming rarer due to overfishing.

According to the study, the proportion of fish caught before reaching "Lm50" -- the length at which 50 percent of a species reaches sexual maturity -- rose from 77.7 percent in 2022 to 93.3 percent in 2025.

Greenpeace said Lm50 is an important indicator of fish population health and a key reference point for fisheries management.

The NGO conducted the survey primarily through sampling at seafood auction markets, supplemented by data collected from fish vendors. The study covered fishing harbors in Kaohsiung, Yilan County, Pingtung County and Penghu County.

The three-year survey points to severe overfishing, said Ho Hsuan-ching (何宣慶), an associate professor in the Department of Aquaculture at National Kaohsiung University of Science and Technology who participated in the research.

Without effective management measures, fish populations could face bottleneck effects that result in progressively smaller fish, Ho said. In turn, usable fishery resources would decline and could even be mostly depleted within the current generation, he warned.

The investigation also found evidence of extensive trawling activity in waters where such operations are prohibited.

Although the Fisheries Act bans trawling within three nautical miles of shore, Greenpeace said trawlers logged more than 30,000 operating hours off Yilan County between 2023 and 2025. Penghu and Pingtung counties each recorded more than 10,000 hours during the same period.

However, Greenpeace Ocean Project Director Huang Hsin-tung (黃欣彤) said the Fisheries Agency recorded only 24 penalties for illegal trawling in 2025, while authorities in Yilan, Penghu and Pingtung counties recorded none.

The waters within three nautical miles of shore serve as important breeding and nursery grounds for many marine species, Huang said, adding that the areas remain subject to intensive fishing with insufficient oversight from central and local governments.

Greenpeace urged the Fisheries Agency and local governments to strengthen enforcement efforts and allocate more funding for marine conservation.

Government actions

In response, the Fisheries Agency said it respected the group's advocacy efforts but argued that long-term monitoring of fish population structures is needed before determining why fish are becoming smaller.

The agency said factors such as catch selectivity, the age and size of fish entering waters around Taiwan, and changes in biological maturity levels must also be considered.

It noted that size limits have already been established for species including mangrove crabs and mahi-mahi based on scientific research, while local governments have adopted fisheries management measures, including seasonal and area-based restrictions and minimum catch sizes.

The agency said it has been conducting long-term assessments of major commercial fish species and is working with the Fisheries Research Institute and the National Academy of Marine Research to develop medium and long-term projects and secure funding for fishery resource assessments.

It added that measures such as reducing the number of operating fishing vessels, regulating fishing gear and methods, managing economic coastal species, protecting habitats, restoring resources and strengthening enforcement are all aimed at maintaining sustainable fishery resources.

According to the agency, annual fish catches have remained at roughly 170,000 metric tons over the past five years.

The agency also said it penalized 64 trawling-related violations between 2023 and 2025.

Finally, it argued that Taiwan's fisheries involve a wide variety of fishing and trading practices, including auctions, direct sales and transactions with processing plants. As a result, relying primarily on data from fish markets could introduce sampling bias.