In May, olive flounder are in the phase of recovering after spring spawning. According to the National Institute of Fisheries Science’s Fisheries Biological Resources Information System, the main spawning period for Korea’s West and South Sea olive flounder (neobchi, Paralichthys olivaceus)’s primary spawning season is February–June, and immediately after spawning the fish cling to deep sand‑gravel bottoms to resume feeding. The rig essential for this period is a single thing, ‘How long and how steadily you scour the bottom’.
Chronologically, May is also the start of the olive flounder season. Olive flounder are at peak season from May to October and, more broadly, can be targeted from April to November. As more individuals finish spawning, the first month when bites become active is precisely May.
01Where are May olive flounder and under what conditions?
Olive flounder are a bottom‑dwelling species. Even under normal conditions they rarely hover more than 1 m above the bottom, and during the recovery period in May when water temperatures fluctuate between 12–17 °C they cling even more tightly to sand‑mud‑gravel substrates. Monitoring data of artificial reefs released by the Korea Fisheries Resources Agency (FIRA) also show that in spring olive flounder are caught more often on the sand flats beneath or beside reefs than around the reefs themselves.
When olive flounder feed actively the target temperature range is 15–22 °C Thus, the May coastal waters enter the lower end of this range, and once water temperature exceeds 15 °C bites become noticeably active. By region, the entire West Sea is the main arena and parts of the South Sea also enter the season.
In other words, if the lure stays too high above the bottom, the olive flounder passes it out of sight means that. Conversely, if it is pulled down to the bottom, rockfish and crabs take the bite first. That’s why field guides commonly recommend a distance of “about 30 cm off the bottom.”
02The sinker is the minimum weight to feel the bottom
If the sinker is heavy, the rig gets stuck on the bottom. If it is light, currents push it away and it loses contact with the bottom. For May West Sea and South Sea coasts, the commonly used weights are as follows.
The principle is simple. the minimum weight that produces a ‘tap’ feeling when the sinker hits the bottom If heavier, bite perception dulls; if lighter, the rig drifts diagonally and passes over the olive flounder’s head.
03Hook and worm are ‘size that fits one bite’
Olive flounder have large mouths, but during the May recovery phase they do not chase overly large baits. A 4–5 inch shad worm or grub worm with a #2/0–4/0 jig head is standard. For colour, white or pearl on overcast days, and motor‑oil or natural tones on clear days work well.
The moment an olive flounder bites the worm is usually not just a single “tap”, but a sequence of “tap → pause → heaviness”. If you hookset on the first signal, it’s easy to lose it. Wait one beat until the heaviness is felt in your hand.
04Use a thin line, primarily braided line
Olive flounder bites are delicate. Mono line has a lot of stretch, which blurs bottom feel and bite signals. PE braided line 0.8~1.2-go with a carbon shock leader 3~4-go 1.5 m is the basic combo. Braided line is not easily pushed by wind or current, and transmits the hook tip signal directly to the hand.
05Post-cast routine
- After casting, let out line until the sinker touches the bottom.
- When a bottom signal arrives, turn the reel two or three turns and lift slightly — this point is “30 cm off the bottom”.
- Lightly lift (lift) at the rod tip → maintain tension while pulling (polling).
- During polling, if the line suddenly stops or the lift loses weight, it’s a bite.
Repeat this routine 5–7 times per cast, and if there’s no bite, shift the casting angle by 15–20°. Olive flounder often have another individual within a 5 m radius of a caught one.
06May olive flounder, the tide is more important than the time of day
According to the Ministry of Oceans and Fisheries Fisheries Information & Communication Headquarters tide tables, May has a large difference between spring tide and neap tide. Olive flounder are from the end of ebb to one hour after high tide, and the first hour of flood tide where bites concentrate. During slack tide (still water) they hardly move, so checking the tide table before a fishing trip is essentially mandatory.
07First May outing, safety check
Olive flounder outings are divided into boat (on‑boat) and rocky shore/breakwater, and precautions vary with environment. May marks the start of the full‑season outings, so for the season’s first trip double‑check basic safety rules.
- On‑boat seasickness— The first outing in the spring swell tends to cause seasickness. Get enough sleep the night before, take motion‑sickness medicine 30 minutes before boarding, and keep your gaze on the distant horizon.
- Rocky shore fall— The biggest accident factor when targeting olive flounder on rocky shores. Spike shoes and life jacket are essential; avoid solo entry at night.
- Breakwater slip— Avoid moving on the algae‑and‑wet slippery tetrapod, and cast only where the footing is stable.
Olive flounder is not a flashy species. Bites are quiet, and hooksets are a beat late. However, when the rig is held exactly 30 cm off the bottom, May olive flounder surprisingly give an honest answer.