Our last posting recognized the Storms of November as notable passings from a human perspective. What do massive storm events, particularly windy ones, mean for our fish? The Great Lakes provide some interesting examples of how these disruptive forces of nature may be essential to the renewal of fish populations. The frequent occurrence of windstorms in spring and fall seems to be at odds with the observation that so many of our favorite fishes spawn either in the spring, or in the fall. Strong and persistent winds move millions of tons of water, which, in turn, move mountains of gravel on beaches and shoals of exposed lakeshores. Doesn't this conjure up visions of fish eggs being ground to paste by pounding surf? Perhaps, unless there is some strange convergence between the ecology of gravel bars, and the physics of fish eggs.
Wednesday, November 3, 2010
Gordon Lightfoot had it right, "With the gales of November remembered." The meteorological service and statisticians are at odds with the literati (e.g. Shakespeare, Frost, Conan Doyle, Whittier, Longfellow) who insist that gale-force storms are more frequent and intense around the vernal and autumnal equinoxes. Here in Minnesota, I have to cast my lot with the literati, considering the latest cyclonic circulation. Our record low pressures, 955 millibars of mercury, and near-record sustained wind velocities at Rochester, 24-hr average over 31 mph, convince me that late October and early November bear watching for outdoorsmen of every stripe. Recent memory of such events include the Great Hallowe'en snowstorm, Oct. 30, 1991, which turned into the "Perfect Storm" when it reached Atlantic waters, the Nov. 10, 1975, "Edmund Fitzgerald" storm, and the Armistice Day Blizzard of 1940. An interesting event occurred a century and a half earlier, on Nov. 10, 1835, before official weather recordings, when newspaper accounts reported the lower Great Lakes "stripped of sail" by a massive windstorm. Fortunately for the trout in the Driftless Region, little precipitation accompanied the winds and our streams showed no obvious discoloration after the storm. The Winona Fly Factory even reported some late season action in northern Iowa streams after the hatches had been battened down (pun intended) after the storm. Our next commentary will address the question of the role of fall storms on fall-spawning fishes in the Great Lakes.