The Three-Minute Outdoorsman: Wild Science from Magnetic Deer to Mumbling Carp

35. Mumbling Along

t h e t h r e e - m i n u t e o u t d o o r s m a n 134 with the old eggs comes from the common names people have used for birds. For example, the name Labrador Duck was sometimes used as a name for a domestic, Mallard-like duck now known as the Black East Indies breed. So, an old common name associated with some old eggs gave the mistaken impression that one of the English eggs was from “the” Labrador Duck. In any event, thanks, I guess, to modern technology, we now actually know less about Labrador Ducks than we thought we did. I guess it’s better to know this than to think we had a few more glimpses into the biology of this long-extinct species. Certainly the museums now can correctly identify the eggs, although they might be displeased that they were possibly duped long ago into buying eggs that were either honestly misidentified or deliberately falsified. The museum in Germany (Dresden) purchased at high cost their six “Labrador Duck” eggs in July 1901—now it’s time to update their catalog! 35 mumbling along lessons from the past about stopping the spread of exotic species The spread of aquatic invasive species has become epidemic. Departments of natural resources struggle to stem these invasions, although their efforts sometimes seem too little too late. Many procedures have been introduced to reduce spreading from lake to lake. Removing aquatic vegetation that hangs from boat trailers is one. Others are to drain live wells and bait buckets and to remove a boat’s plug when leaving a lake or river. If these actions are not taken, invasive plants and animals harbored in these small amounts of water can be easily exchanged between bodies of water. I have pulled several pieces of debris from the bottom of the St. Croix River with zebra mussels attached. I N T H E W A T E R 135 These minor inconveniences are actually pretty annoying ; just ask the many who have forgotten to put the plugs back in their boats before the next launch, after decades of not needing to. But these inconveniences pale when we see underwater pictures of large, spreading beds of exotic zebra mussels on the bottom of the premier walleye fishery Mille Lacs in central Minnesota . Shortly after their introduction, they spread, figuratively speaking, like wildfire. And they have an impact, as I found in the summer of 2013 when I visited Mille Lacs and observed how much clearer the water had become, a known effect of zebra mussels. Although clearer water might seem a good thing, it’s not if that’s not the lake’s normal water clarity. But what’s the big deal? Having a new species on the landscape is not a novel occurrence; it happens in nature all the time. Over scales of thousands of years, entire communities of plants and animals have moved great distances, such as the wholesale recolonization of areas like Minnesota and Wisconsin following retreat of the last glacier. We also see ranges shift over the short term. Many birds, like the little Blue-gray Gnatcatcher, have markedly extended their ranges northwards in the past twentyfive years. And who in Minnesota needed a recipe for road-killed opossum thirty years ago? The problem of introduced species is often greatest when the exotics come from faraway places and have some advantage in their new environment: they may have adaptations that make them more successful than the local, native species, or they may be preadapted to a man-made niche that only recently became available. In addition, introduced species typically arrive without their typical predators, and competitors are lacking. Carp are a prime example, and we have known for years that they can harm aquatic environments. Only recently did I see some figures that put this concern in perspective. And the information isn’t new; it comes from an article published by Alvin Cahn in 1929 in the journal Ecology. He told a fascinating story about a small lake in southern Wisconsin and its tale of woes from introduced carp. It reinforces that we t h e t h r e e - m i n u t e o u t d o o r s m a n 136 should be concerned about introduction of exotic species, and it...