Understanding trout movement is intrinsic to locating and catching them. This piece is based around the types of rivers we fish in the New Zealand North Island spate type rivers, as spring fed rivers have different characteristics. There is a distinct pattern of trout movement through the year. In the autumn, fish move steadily upstream to their winter spawning grounds, with browns heading off a few months before rainbows. During spring and summer, they drop back downstream again. Around February to April, a mass of juvenile rainbows, or 'dinks' as we affectionately call them, are often found spreading themselves throughout the river system. At this time, they weigh a few ounces. Fast forward to the following summer at a year and a half old, they're as fat as butter and weigh as much as a pound or so.
There is also a noticeable pattern of fish movement on a micro level that extends to fine tuning the location of their respective positions in pools and runs according to temperature and water level. In October, when the bigger fish are beginning to arrive back in the lower to middle reaches, they are usually in the lower two thirds of pools and a cast into the fast water at the head of a pool is often fruitless. However, by Christmas, the top half of pools offer the most productive water and by early February, the fish are often packed in the top quarter.
High temperatures and low water levels push fish into the bubbly oxygenated water with the prime honey holes being the drop-offs from a riffle into a pool where the water is about thigh deep. A brief study of satellite maps should reveal potential locations for trialing. I noticed that by double checking some of our local hot spots on a topographic map, a common denominator is the presence of shingle seams - the geology and gradient are such that ideal pools and runs form frequently in these areas. The fish are often concentrated during high summer, with ninety-nine percent of the fish being found in one percent of the water. The trick is to find the one percent and focus solely on that.
Systematically searching likely areas will help to build up a picture of where fish are likely to be found. Some hotspots may be quite confined so it pays to search thoroughly. Trout will find a spot on the riverbed that is like a favourite armchair to them. Although, they maybe clinging to the lip of a drop-off in low water, hot weather conditions, a dose of rain that cools the water is likely to find them drop back into deeper water ten or twenty meters downstream. Hammering a hotspot is likely to empty it in short order, so it may be beneficial to let it rest for a week or two. Hotspots can sometimes remain hot for a number of years, but many succumb to the ravages of winter floods. Plenty of my old hotspots are now dry land but then I love the challenge of discovering new ones.
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