Vanntemperatur og årstider

Fish are cold-blooded: their body has the same temperature as the water. That is why the water temperature governs how active fish are, how much they eat and where they hold.

What each species likes

• Perch and pike are active over a wide range, but pike do best in cooler water and turn sluggish when it gets really warm.
• Zander like warmer water and become more active when the surface reaches about 15 degrees.
• Trout, char and grayling want cold, oxygen-rich water. When it gets warm they go deep or to running water.

Season by season

• Spring: shallow bays warm first. Fish go there to feed and spawn, and the bite can be very good.
• Summer: in deep lakes a thermocline forms, a boundary between warm surface water and cold bottom water. Below it the oxygen can run out, so fish often hold just above it.
• Autumn: the water cools and mixes. Many predators feed up before winter, and for many anglers autumn is the best time for big pike and perch.
• Winter: fish are slow and often deep, where the water stays at around four degrees. Jig slowly.

Oxygen

Warm water holds less oxygen than cold. During heat waves shallow bays and small lakes can become so short of oxygen that fish turn sluggish or move. The morning is then often best, before the sun has warmed the water. Running water, inflows and places where wind stirs the water hold more oxygen and can be worth seeking out.

Quick changes

A sudden change in temperature, such as a cold night in spring or a cold wind turning over the surface water, can make fish sluggish for a while, even if the new temperature is fine in itself. Fish need time to adjust. A couple of days of steady or rising temperature in spring often give the best fishing.

Measure and log

Finnegas saves the water temperature where it is available, for example from marine data on the coast. If you have your own thermometer, note the temperature on the fishing day, and over time you will see at what temperatures your own water fishes best.