01Environmental differences between rocky‑shore fishing and boat fishing

Olive flounder is a ambush predator with a left‑right symmetrical body that lies flat on the bottom waiting for prey. In the West Sea coast it mainly inhabits sandy‑pearl bottoms at depths of 10–200 m (NIBR Korea). In June the water temperature rises to 15–22 °C, prompting olive flounder to move into shallow coastal waters (30–80 m) and actively search for food. Around rocky shores the current is strong and wave heights fluctuate between 1–2 m. In contrast, on a boat the current and waves are relatively steady, and when the vessel speed is 2–4 knots (≈3.7–7.4 km/h) it is easy to adjust the worm so that it passes precisely through the 20–40 cm depth layer. These physical differences directly affect rig selection and bite detection.

West Sea coast
Rocky‑shore zone
30–80m
May–September
South Sea coast
Boat zone
20–60m
June–October
Outer islands
Deep sea
100–200m
All year round

02Core principles of the down‑shot rig and its application to rocky shore and boat fishing

Olive flounder down‑shot fixes the sinker to the bottom, drops a leader 40–50 cm long, and lightly floats a 4‑inch minnow‑shad‑tail worm. Olive flounder reacts to prey passing 20–40 cm above, so the float height is critical to keep the worm off the bottom. Use a sinker of 25–40 go (112–150 g); if the current is 0.5–1.0 m/s increase to 35–40 go (≈130 g). Too light a sinker will rise, pulling the rig out of the depth layer and reducing bite sensitivity. Use a 3/0–4/0 straight hook; on bright days (water ≥ 18 °C) choose white or red worms, and on colder water (≤ 15 °C) use chartreuse. On rocky shore the rig tends to shake from waves, so keep the leader short at 30 cm to let the worm touch the bottom quickly; on a boat, when the current is weak, extend to 50 cm so the worm stays afloat longer.

Sinker size
25–40 go (112–150 g)
Leader length
30~50 cm
Hook size
3/0–4/0 straight hook
Worm type
4‑inch minnow‑shad‑tail (white·red·chartreuse)

03Safety points and practical tips

⚠ Common mistakes
  1. Insufficient sinker weight– When the current exceeds 0.5 m/s, using a sinker 25 go or smaller causes it to rise and the rig leaves the depth layer.
  2. Excessive leader length – Over 60 cm makes the worm float too high above the 20–40 cm layer, reducing bite sensitivity.
  3. Slipping on rocky shore – Areas where water flows between breakwaters and rocks are very slippery; waterproof shoes and a safety rope are essential.
⏱ Golden time
Sunset ± 2 h
As water temperature drops, olive flounder moves into shallow water, causing a sharp increase in bites
Early morning 4–6 a.m.
Current weakens, sinker stabilizes, leader length is easy to adjust
Midday 12–14 p.m.
Water temperature peaks, olive flounder moves to deeper water and bites decrease

When targeting olive flounder on rocky shore and boat, the most important factor is accurately assessing depth‑temperature‑current and adjusting sinker weight and leader length accordingly. June marks the end of the West Sea spawning period and water temperatures rise to 15–22 °C, so olive flounder is highly active in shallow coastal waters (30–80 m). On rocky shore, strong waves and abundant rocks require safety caution; on a boat, fine‑tune the rig based on vessel speed and current. Following the specific figures provided (sinkers 25–40 go, leaders 30–50 cm, 4‑inch worm) and the safety points will allow you to efficiently target the June olive flounder season.