Genkai Landings and Sea Temperature: Monthly Data

🌐 日本語版（玄海の水揚げと海の水温）はこちら / Read this page in Japanese

Fish landings in Karatsu, month by month

At the Genkai fisheries co-op market in Tobo, Karatsu (Saga, Japan), landings in Aug 2026 were 59.1 tonnes (81% of the same month a year earlier, 69% of the normal). Over the 12 months from Sep 2025 to Aug 2026 the market landed 1,088 tonnes, 113.8% of the year before. On 1 Sep 2026 the survey vessel measured 28.8 °C at the surface of the coastal station St.18, 2.6 °C above normal.

Karatsu Farm & Food compiled these figures from the monthly bulletin of the Saga Prefectural Genkai Fisheries Promotion Center. Landings are the weight of fish and shellfish landed at the market. The normal is the mean of the same month over the previous five years. Set nets are fixed nets placed near the shore; their landings are part of the whole-market figure. Every number can be traced to its source issue in the ledger below.

These are landings at one market (Genkai co-op, Tobo, Karatsu), counting only fishers registered in Saga. They are not the catch of Karatsu city or Saga Prefecture.

Why we make this page

The Saga Prefectural Genkai Fisheries Promotion Center publishes the state of the sea off Karatsu every month in its bulletin. Each issue is a separate PDF, so comparing many months takes effort. In August 2026 Karatsu Farm & Food began a trial of using AI (Claude) to read the bulletin tables, check the sums and turn them into charts and tables. The aim is to make public data readable by anyone in the region, and by AI, so that changes in the sea off Karatsu can be checked.

Every figure is checked against the source PDFs and can be traced to its issue (first version 4 August 2026; published on this site 8 October 2026).

Whole marketof which set netsNormal (5-year mean)

Overlay old-basis figures

Monthly landings, Jul 2024 to Aug 2026

Across 26 months the highest month was Nov 2025 at 143.7 t and the lowest was Feb 2025 at 46.2 t. Whole-market landings have been below normal for 6 consecutive months, from Mar 2026 to Aug 2026.

The bulletin changed its table format and counting basis in the August 2025 issue, so old and new figures do not join (May 2025: 94.7 t on the old basis, 88.7 t on the new). The main line uses new-basis figures only; old-basis values can be overlaid for reference.

Station St.18 coastalSt.4 Iki Channel

Warmer than normalCooler than normalLandings vs normal (new basis)Same, old basis

Sea temperature beside landings

The survey vessel measures water temperature each month at two stations off Karatsu: St.4 in the Iki Channel and St.18 near the coast. At the coastal station St.18, surface temperature was below normal in 6 of 7 surveys from December 2024 to June 2025, and above normal in 12 of 12 surveys from July 2025 to June 2026.

Temperature normals are 20-year means and landing normals are 5-year means. The two are shown together for comparison only; this does not show that temperature caused the changes in landings.

What lands when, Sep 2025 to Aug 2026

In this year the peak months were: japanese jack mackerel in Nov, chub mackerel in Sep, red seabream in May, japanese spanish mackerel in Nov, japanese sardine in Feb, japanese amberjack in Mar, chicken grunt in May, yellowtail amberjack in Dec. This is one year of records and will vary from year to year.

Same months a year earlierSep 2025 to Aug 2026

Species: 12 months against the year before

Comparing Sep 2025 to Aug 2026 with the same months a year earlier, the largest increases were japanese jack mackerel (+83 t), chub mackerel (+59 t), japanese sardine (+50 t) and the largest decreases were red seabream (-17 t), japanese amberjack (-15 t), swordtip squid (-10 t).

Monthly figures

Survey sea temperatures

Source ledger

All 24 issues used. "Check" is the gap between the sum of species rows and the table total (small gaps come from rounding in the source).

How the data was made

Tables were read from the bulletin PDFs (October 2024 to September 2026 issues) and each species sum was checked against the table total. Four temperature tables were images and were read by eye. Each month uses the figure from the first issue that reported it as the current month; July 2024 to June 2025 come from the prior-year column of new-format issues. Where a later prior-year column differs, the ledger shows both. The July 2025 issue has no landings table, and the November 2024 survey was not carried out.

▶ Download the data as CSV (genkai-landings.csv)

What comes next

The sea is connected. Working with the Tsushima WAVE Project, in which Karatsu Farm & Food takes part, we plan to make the sea data published by prefectures across Kyushu readable in the same way, not only for Karatsu. We will start with Tsushima and Iki, using the landings and water temperature information published by Nagasaki Prefecture, and aim to show the seas of Karatsu, Iki and Tsushima as one connected picture (plan as of October 2026).

Keep watching the numbers

With AI, data turns into neat charts in moments. What matters is not the presentation but what is happening to the sea and the fish. Landings at the Genkai co-op market were higher over the last 12 months than the year before, while they have been below normal for 6 consecutive months since Mar 2026. Karatsu Farm & Food updates this page every month to keep a record of the sea off Karatsu.

FAQ

Q1. Is this the catch of Karatsu city?

No. These are landings at one market, the Genkai fisheries co-op market in Tobo, Karatsu, counting only fishers registered in Saga Prefecture. They are not the catch of Karatsu city or Saga Prefecture.

Q2. Where does the data come from?

From the monthly bulletin 'Gyokaikyo Joho' published on the Saga Prefecture website by the Saga Prefectural Genkai Fisheries Promotion Center. Karatsu Farm & Food read the tables of 24 issues and records the source issue for every figure.

Q3. What does 'normal' mean?

For landings, the normal is the mean of the same month over the previous five years (the window moved from 2020-24 to 2021-25 in the January 2026 issue). For sea temperature, it is a 20-year mean.

Q4. How often is it updated?

Monthly, after the prefecture publishes each bulletin.

About this page

Compiled by Hiroaki Kojima, Vice Director, Karatsu Farm & Food. Contact: kojima@karatsu-f-f.com (contact page)

Related links

▶ Saga Prefectural Genkai Fisheries Promotion Center bulletin (Japanese)
▶ 玄海の水揚げと海の水温（日本語）