Lake thermoclines and jigging for trout

Trout and salmon commonly lie deep in lakes during the heat of summer days seeking cool water, security and the thermocline. This is where the cooler nutrient-rich waters meet warmer light-filled surface waters. This layer could be around 20 metres deep, but will vary between lakes and seasons. Algae need nutrients and light, so they are often concentrated around the thermocline. Lots of algae means lots of zooplankton, and of course small feeding fish, which attracts larger fish.Often these larger fish are out of the reach of common angling methods, but the combination of a good fishfinder and jigging can be very successful. Jigging is a technique commonly used in the highly productive North Island lakes, but rarely seen in the South. It requires good use of your sounder to identify at what depth fish are present, perseverance and good lure selection.

The method simply involves lowering and raising lures (jigs or flies) from an unmoored boat by working the rod in a fashion that entices fish to strike. Use a metal jig as the bottom lure (or combination sinker), with a single or double wet-fly dropper.

Fish often take in a gentle manner, so sensitive rods of between 1.5-2 metres in length are important. Level-wind reels are recommended, and spooled with braid because of its low stretch qualities and good strength relative to line diameter, allowing increased sensitivity and improving hook-ups.

If you start dragging the lure assembly too far from the boat wind in and start again and if all else fails, change lures or pour a cup of coffee and wait for the bite time.