01How water temperature decides bite activity
When water temperature changes by 1 °C, fish metabolic rate shifts by an average of 2‑3 %. This is confirmed by the temperature‑metabolism equation (metabolic rate = k·e^0.03·T) measured in NIFS research.
Higher metabolic rates stimulate more active foraging, while colder water reduces movement to conserve energy. Thus, water temperature directly controls the timing of feeding, i.e., the bite moment, for each species.
When temperature is within the optimal range, muscle efficiency peaks and even subtle motions are detectable underwater. This aligns with the correlation between water temperature and muscle‑contraction speed (muscle‑fiber contraction speed ∝ √T).
02Optimal temperature ranges by species
Korean rockfish (Sebastes spp.) feed most actively at 15‑20 °C and mainly inhabit depths of 10‑25 m. Temperatures above 22 °C sharply reduce activity due to lower dissolved oxygen.
Sea bass (Dicentrarchus labrax) prefers 12‑18 °C, intensifying foraging in shallow water (5‑15 m). Below 10 °C growth slows by about 30 %.
Olive flounder (Paralichthys spp.) favors 10‑16 °C and shows migratory behavior near the bottom (20‑30 m). At 8 °C or lower it shifts to a low‑activity state.
03Rig adjustments according to water temperature changes
When temperature is below the optimal range, use a low‑speed reel (1‑2 rev per minute) and light lures (5‑10 g) to minimize resistance.
Conversely, in higher temperatures select a high‑speed reel (3‑4 rev per minute) and heavier lures (15‑25 g) to generate fast, water‑driven motion.
As depth increases, temperature differences shrink; below 20 m the water temperature varies only 1‑2 °C. Adjust retrieve speed to match fish reaction time.
- Ignoring temperature and always using large lures drastically reduces bite probability.
- Mismatched retrieve speed fatigues fish and causes them to flee.
04Practical application scenarios
When surface water is 16 °C, target the zone where Korean rockfish and sea bass are both active and use a 12‑18 g minnow‑style lure.
At 25 m depth with water at 10 °C or below, olive flounder and herring dominate, so choose a slow bottom retrieve with an 8‑12 g lure.
If water exceeds 22 °C, salmon move upstream; a fast‑turn reel and a 20‑30 g spoon‑type lure work best.