Small Fish, Unequal Fortunes: Japan’s Anchovy and Round-Herring Assessments

A fishery can land fewer fish and still be taking too much from a depleted population. Another can have a substantial breeding stock while the next generation is faltering. Japan’s latest assessments of anchovy and round herring put those two situations side by side—and explain why a headline about “Japan’s sardines” would conceal more than it reveals.^[1][2][3]

Released on September 15, the fiscal 2026 assessments concern the Tsushima Warm Current stocks of Japanese anchovy, or katakuchi-iwashi, and round herring, urume-iwashi. Their geographical frame is the Sea of Japan and East China Sea side of the country. These are not assessments of every anchovy or round herring population around Japan, and they do not cover the Pacific and Seto Inland Sea stocks as one national unit.^[2][3]

The central estimates describe 2025. Numbers for later years are projections. That distinction matters to anyone trying to connect a scientific report with today’s catch, next year’s fishing plans or the price of dried fish.

Two fish, different warnings

The clearest comparison begins with three different quantities. Total biomass estimates the weight of the stock. Spawning biomass estimates the breeding component. Catch records fish removed by fishing over a period. None can substitute for the other: a fall in landings can reflect fewer fish, fewer trips, different targets or changes in where fish are available.

Rounded figures from the Japan Fisheries Research and Education Agency’s provisional detailed assessments. *Anchovy catch excludes shirasu, the larval catch. The two spawning-biomass targets use different reference points. ABC is scientific catch advice, not an adopted quota or a forecast of actual landings.^[2][3]

Anchovy’s estimated biomass fell from 93,000 tonnes in 2021 to 22,000 tonnes in 2025. Its spawning biomass declined from 47,000 to 14,000 tonnes over the same period. The rounded breeding-stock estimate was unchanged between 2024 and 2025, but the assessment classifies the five-year trend as declining.^[2]

The adopted target is 68,000 tonnes of spawning biomass, a reference point designed around maximum sustainable production from the age-zero and age-one fish central to this fishery. The report labels it SB97%msy. It is distinct from the conventional MSY spawning-biomass reference of 84,000 tonnes. Against the adopted target, the 2025 breeding stock stood at approximately 0.21 times the required level: roughly one-fifth.^[2]

Fishing pressure was assessed at 1.06 times the benchmark associated with that adopted target. This does not mean fishers caught 106 percent of the stock. It compares a measure of fishing mortality with a reference level. The practical lesson is that smaller catches do not necessarily provide enough relief when the population supporting those catches has also shrunk.^[2]

A strong adult stock cannot guarantee tomorrow’s fish

Round herring presents a less depleted picture. Its 2025 spawning biomass was assessed at 1.75 times the 54,000-tonne MSY target, with a stable five-year trend. Total biomass reached 136,000 tonnes in 2023, fell to 104,000 in 2024 and rose to 112,000 in 2025. That is variation, not uninterrupted growth.^[3]

The warning is recruitment: the addition of young fish to the stock. Estimated recruitment dropped sharply in 2025. For a fish with a lifespan of about three years, a weak incoming generation deserves attention even when the adult population looks comparatively strong. Fishing pressure, meanwhile, was just above its MSY benchmark, at 1.01 times that level.^[3]

Those findings do not support a simple instruction to replace anchovy fishing with unlimited round-herring fishing. A management decision must consider the condition of each stock, the younger fish entering it and what fishing different species together actually involves.

The observation problem: fleets change as well as fish

These estimates are reconstructed from evidence rather than produced by a census of every fish. The assessments use cohort analysis, following age groups through catch records, alongside indices from egg surveys and fishing activity. For anchovy, the inputs include standardized catch per unit effort from small and medium purse-seine fisheries in Nagasaki. This assessment also incorporates a larval-density index from the East China Sea.^[2]

Standardization tries to account for differences in fishing conditions so that a catch-rate index more usefully reflects abundance. It cannot make every uncertainty disappear. Nor should estimates published in different years automatically be treated as an unchanged historical series when methods or inputs have been revised.

The round-herring report raises a particularly consequential complication. Fleets have shifted their targets as sardine and chub-mackerel abundance increased and anchovy declined. Reduced activity by fisheries targeting small fish for processing can also alter records of juvenile round herring caught alongside them. Researchers therefore need to understand changes in fishing behaviour as well as changes in fish abundance.^[3]

This is not a reason to dismiss the recruitment warning. It is a reason to examine size composition, fishing methods and survey evidence carefully. A catch record is evidence about the sea obtained through an economic activity; changes in that activity can change the evidence.

The anchovy report likewise does not establish a single cause of decline. Its supplementary discussion considers fishing pressure, poor recruitment, distribution and spawning-area changes, and interactions with changes in other fish stocks. Parts of that account remain hypotheses requiring further investigation. Neither “climate change did it” nor “fishing alone did it” is a conclusion that this assessment can establish.^[2]

From biological advice to rules at sea

The reports calculate 2027 ABC advice of 2,200 tonnes for anchovy and 19,000 tonnes for round herring under their specified harvest scenarios. These figures should not be presented as already adopted total allowable catches. Scientific advice, management decisions and eventual landings are separate stages.^[2][3]

Japan’s management history helps explain why. The country has combined licensing and restrictions on fishing methods and seasons with fishers’ voluntary measures, including closures. A national TAC system began in January 1997. The revised Fisheries Act, effective December 1, 2020, strengthened the framework for management around maximum sustainable yield and explicit stock reference points.^[5]

MSY is a long-term management concept, not a promise that a fixed volume can safely be caught every year regardless of the stock’s condition. Reference points and harvest rules are intended to connect changing biological evidence with decisions about removals. For these two stocks, the reports use harvest scenarios established through management discussions and the Fisheries Policy Council in 2023.^[2][3]

The consequential questions come after the headline number. How will any required adjustment be divided among places and fisheries? Which sizes of fish should be protected? What can a vessel do when species occur together? The biological assessment supplies essential evidence; it does not settle every question of implementation.

Why the unit of concern is also a community

The anchovy assessment describes set-net fishing in the northern Sea of Japan, purse seines and set nets farther west, and small and medium purse seines on the Kyushu side. Round-herring fishing is concentrated from western Kyushu toward San-in. These are different operating environments, so a reduction in available catch does not translate into an identical adjustment everywhere.^[2][3]

For communities, the questions extend beyond vessels. Can processors handle a different size of fish or a less predictable delivery schedule? Can a mixed fishery avoid a vulnerable species while continuing to catch another? Would a higher landing price offset reduced volume, or would costs absorb the difference? These are questions raised by the assessments, not economic outcomes measured in them.

The reports do not establish losses in household income, processing employment or regional revenue. Putting a yen value on the local consequences would require additional evidence. But planning without those questions would leave a gap between a sound biological rule and a rule that communities can carry out.

What a bowl of rice adds to the story

The cultural value of small fish is easier to see at the kitchen table. The agriculture ministry’s account of iriko-meshi, a rice dish from western Kagawa, describes anchovy boiled and dried into iriko. The fish provides stock, while its flesh is cooked into the rice. Around Ibukijima, rapid handling from catch to processing and care not to damage the fish contribute to product quality.^[6]

This example belongs to the Seto Inland Sea, outside the stocks assessed here. It illustrates food culture, not evidence of a Tsushima-stock shortage in Kagawa. Its relevance is the chain of value: the same small animal becomes a livelihood, a processing skill and a familiar meal. Conservation has a human destination as well as a biological objective.

The next assessments will need to show whether anchovy’s breeding stock and recruitment improve, and whether round herring’s weak incoming generation persists. Management decisions will show how that evidence is used. Following those developments requires keeping species, sea areas and years distinct—and remembering that sustaining a fishery means sustaining both the fish and the capacity to make a living from them.