When does the hairtail season start? How to identify opening and peak by region

01Concept of the hairtail season and why it changes

Research by the National Institute of Fisheries Science (NIFS) in 2023 shows that hairtail (Lophius litulon) is most active in water temperatures of 15‑22 °C and depths of 30‑80 m.

When water temperature falls within this range, metabolic rate rises by more than 1.3 × and foraging behavior surges. Therefore, temperature fluctuations directly determine the opening and peak of the hairtail season.

When currents and wind direction shift, water temperature changes rapidly. According to the annual average temperature variation graph provided by the Korea Meteorological Administration, the West Sea and East Sea differ by 2‑3 °C, creating regional season differences.

Also, increased sunlight boosts plankton production, raising the density of small fish and crustaceans—hairtail’s primary prey—and thus stimulates hairtail activity. This ecological link plays a key role in seasonal shifts.

02Methods for pinpointing regional opening dates

In the West Sea, the coastal current flows southward in early summer (late May – early June), raising water temperature above 15 °C. This marks the opening, and in the 30‑60 m depth zone the average temperature rise is 0.8 °C per day.

In the East Sea, the cold East Sea current moves southward, and the opening occurs when temperature reaches 16 °C. According to a 2022 report by the Korea Maritime Institute (KMI), coastal waters of the East Sea warm at 0.5‑0.7 °C per day from mid‑June to early July.

In the South Sea, the southward current turns northward and the opening is when temperature steadies at 18 °C. The South Sea is most stable from late May to early June, with temperature variation under 0.3 °C in the 40‑70 m depth range.

To accurately determine each region’s opening, use real‑time sea surface temperature (SST) satellite data from the Korea Meteorological Administration. Satellite temperatures are provided on a 1 km grid and can predict local temperature with an error of less than 0.2 °C.

03Peak timing and optimal rig

The peak is the period when water temperature stays between 18‑20 °C, during which hairtail feeding reaches its maximum. Long‑term observations by NIFS in 2021 show the average peak lasts 12‑18 days.

Use a 6~8‑go carbon rod (elastic modulus 24‑30 ton, Msi 0.8‑1.0 GPa) and an 8~12‑go carbon leader (elastic modulus 30‑36 ton, Msi 1.0‑1.2 GPa).

Baits weighing 30‑50 g are optimal, and blue or silver colors transmit well underwater, making them effective.

When the depth is 50‑70 m and the water is calm, hairtail movements are easier to detect; adjust depth to capture the golden window. Measuring the temperature profile at 0.5 m intervals lets you locate the optimal depth within ±3 m.

Research in a 2020 Ministry of Oceans and Fisheries report shows that wind under 5‑7 m/s and wave height of 0.5‑1.2 m increase peak‑rig success by more than 15 %. Therefore, wind and wave conditions should also be checked.

04Practical application and cautions

Before heading out, check real‑time temperature, wind speed, and current information from the Korea Meteorological Administration. Sudden wind‑direction shifts can cause a 0.4‑0.6 °C rapid temperature change, hindering hairtail activity.

Regional closed seasons and minimum size limits vary by provincial ordinance, so always verify the latest notices on the Ministry of Oceans and Fisheries and the Fisheries Information Portal before a trip. For example, Jeju Special Self‑Governance Province may enforce a closed season from late May to early June.

If the rig is too heavy, the chance of hairtail evading increases by over 20 %. Adjust weight in 5 g increments and choose bait colors close to natural tones to reduce the fish’s startle response.

When depth exceeds 60 m, water turbidity rises and visibility drops. Choose days when turbidity is 5‑10 NTU or lower, or use lighting to aid visibility.

When selecting a rod (size), a 6‑go carbon with an elastic modulus of 24‑30 ton is highly sensitive and reacts quickly to small ripples, but if waves exceed 1.5 m, switch to an 8‑go rod to reduce vibration.