Q.SST & Offshore Fishing
What is a thermocline and does it affect where fish are?
A.
A thermocline is a depth band where water temperature changes rapidly with depth — typically the boundary between warm surface water and cooler deep water. Fish often suspend just above or below the thermocline because oxygen is highest above it and bait concentrates along the boundary.
Thermoclines affect both freshwater bass fishing (summer pattern) and offshore tuna fishing (where to set bait depth). Sonar can show the thermocline as a horizontal layer at typical 30-60 ft depths. SST and depth references on the related pages.