Finding The Fish using the Coriolis Effect


I’ve spent thousands of hour’s staring down a hole in the ice waiting for fish to show up. Anticipation of action helps with the boredom. Sometimes there are minnows to watch but most of the time there is nothing interesting going on.

The one thing always present is a bit of a current, it’s always there to some degree in every body of water. This intrigued me. How is this possible? There is little or no flow in the dead of winter? So what could be causing this this phenomenon? Well the answer is that the flow is caused by the rotation of the earth on its axes, this phenomenon is called the Coriolis Effect.

Depending where you live on the planet we are travelling over one thousand miles an hour as we rotate on our axes, at the same time we are travelling some 27,000 miles an hour as we rotate around the sun on our yearly journey through space.

This creates a clockwise rotation of water north of the Equator and a counter clockwise rotation south of the Equator. This small current is evident in all lakes, ponds and even in bird baths.


During the 80’s, I was Fishing Editor and #1 Columnist for Alberta Fishing and Hunting Magazine and thought that a story explaining this current I called The Zoo Plankton Drift would be an interesting column. This drift is like a tide that always flows in the same direction to us it is barely noticeable, but to a microbe or protozoan it is a raging torrent complete with whirlpools, back eddies and raceways.

So if the water is always drifting in the same direction, obstacles like points, bays, reefs and islands would create back eddies were Zoo plankton would concentrate, attracting minnows that in turn attract game fish. It made sense to me but before I could write my column this had to be proved.

By looking at lake contours, imagining the clockwise drift it is easy to determine were the back eddies would be. After checking out the other three sides of a structure taking note of minnow and game fish populations the fourth side where the back eddy should be always proved to be more active. Most of these areas have a high density of Clams and Mussels on the bottom. Somehow these filter feeders know where the food is and congregate there.

After proving my theories to myself I wrote an article called the Zoo Plankton Drift that was met with a lot of skepticism. That was in 1986, I think. I’ve been experimenting with this theory ever since, summer and winter and have never found any evidence to dispute it.

Using this pattern to locate hot spots over the years has given me some exceptional fishing but the best thing it’s done is saved my valuable fishing time for the most productive areas.

Tight Lines
Rick Crozier