Freshwater mussels are some of the longest-lived animals. Mature individuals often reach ages in the decades and some nearly a century. The oldest mussel recorded was 132 years of age. Sedentary animals they spend most of their lives in a very small area if it suits them. Almost like plants they anchor themselves in the sand and pebbles of a riverbed and await the change of seasons while filtering water for microscopic food sources.
Like all animals the urge to procreate eventually arrives. However, the life cycle of mussels borders on the bizarre. Their reproduction begins with a male and female in close proximity. The male senses the presence of the female and releases sperm into the water to be captured by her to fertilize her eggs. This is where things take a strange twist. The female now exhibits the unusual behavior of attempting to lure a fish to come touch her. Like a fishing lure used by anglers her lure can look just like a minnow, or be brightly colored.
When the fish nips at the lure she spews her eggs into the water where they hook themselves on the fish’s fins or gills. As with ticks the young mussels draw nourishment from the fish until they drop off several weeks later into the riverbed, sometimes miles from where their parents were located. To add more strangeness to this story not just any fish will do. Some mussels have only one, or a few, kinds of fish upon which their young can survive. One type of mussel requires a salamander instead of a fish.
People have used mussels since ancient times for food, tools, and ornamentation. Great heaps of shells discarded by Native Americans lie buried along the banks of the Ohio River sometimes exposed by the erosion of the soil from periodic floods. In more recent times mussels were collected in great numbers for the button industry. From 1890 until the advent of plastics in the 1940’s, mussel shells were the primary source for buttons.
According to the 1917-18 Bulletin of the Bureau of Fisheries there existed a gold-rush mentality in the harvesting of mussels from eastern rivers. Government officials estimated that during a single year in the Ohio River alone over 41 million mussels were killed for their shells and pearls. Another 13 million were taken from the Wabash River, as well as over 10 million from the East Fork of the White River in southern Indiana. In 1909 on the Illinois River approximately 2,600 boats were taking mussels.
Like the supposedly inexhaustible herds of bison, the mussels too were decimated in a matter of decades. Biologists urged the federal government to place restrictions on the harvesting of mussels but the call was never heeded and so the golden age of the shell industry collapsed under its own greed.
It is interesting to note that during the peak of the slaughter, shells on the Ohio River brought around $13 per ton. In the early 1990’s, where it was still legal, shells brought up to $6 a pound for export to Japan. The Japanese used these shells to seed oysters for cultured pearls.
The Most Endangered Animal Group in America
Mussels are now the most endangered group of animals in America and many species have been lost to extinction. The Nature Conservancy is working to improve the prospect of these fascinating creatures by influencing the operation of hydroelectric dams, assisting farmers with conservation practices, and encouraging better wastewater treatment. Locally, a recent survey of mussels on the Blue River in southern Indiana showed a greater number of young mussels than in the past when primarily only older individuals were found.
The next time you see a shell lying on a sandbar or a string of freshwater pearls let them be a reminder of a fascinating animal and the tale of a boom and bust era.