Nebraskaland

beautiful mother-of-pearl nacre on the inside of a mussel shell was popular for button making in the early 1900s. That industry overharvested mussels to the brink of depletion in some parts of the country. In addition, many mussels are only found in flowing waters of streams and rivers. When dams are built, the resulting reservoirs are often too deep, contain too much silt, and provide too little flow to make them habitable for most species of mussels. Dams are barriers to fish that are a crucial component of mussel reproduction and survival. The conversion of grasslands to cropland has led to an influx of silt and chemical-laden runoff from cultivated farm fields into rivers and streams, also affecting mussels. Freshwater mussels are especially sensitive to low concentrations of chemical compounds such as ammonia, phosphate and pesticides. Siltation can cover and destroy mussel habitat or cover and smother the mussels. Livestock can also pose a threat, either directly by stepping on mussels while drinking from streams or indirectly when their waste increases nutrient levels in the water. A single catastrophic event, such as a severe drought, flood or a chemical spill, can wipe out small populations of mussels. Recovery and Reintroduction Hatchery production of mussels in the U.S. began in 1914 with the establishment of the Fairport Fish Hatchery on the Mississippi River in Muscatine, Iowa, an effort by the U.S. Bureau of Fisheries to bolster the button industry. Today, many Eastern states, especially in the southeastern U.S., are heavily involved in propagating mussels. Since 2014, Commission biologists have been working with some of these states and developing their own program to rear and reintroduce mussels to their historic range in Nebraska waters. Recovery and reintroduction efforts intend to restore a species to a portion of its native range where it is extirpated or severely reduced. Recovery programs can include collecting mussels and moving them to a new location in hopes that they will establish populations on their own, as well as propagating species in a hatchery and stocking juveniles to reestablish populations. Since 1997, Steve Schainost, rivers and streams program manager with the Nebraska Game and Parks Commission, has collected over 1,000 relic shells and some live mussels from many Nebraska waterways. Schainost has created range maps using data from his collections, other published literature and museum records. Comparing current and past populations has helped identify which species are in serious trouble and candidates for recovery efforts. APRIL 2017 • NEBRASKAland 43 Mussel Habitat Many actions can improve mussel habitat, including improving water quality and reducing sediment build-up. Creating buffer strips of grasses or trees between water and land helps keep chemicals and pollutants from reaching the water. Practicing good soil conservation techniques, such as installing terraces and using contour farming practices, will reduce sediment run-off. After boating, always clean, drain, and dry all boats, motors, and equipment to keep exotic species from spreading. Tagging is the primary means to track released mussels, allowing researchers to evaluate growth, survival, longevity and mussel movements in the future. Hallprint tags are miniscule, alpha-numeric tags that are glued on one side of the mussel shell. These tags come in different colors allowing biologists to differentiate the year, class, species, location and individual growth of hatchery-raised mussels. PIT (passive integrated transponder) tags are battery-free radio frequency identification tags. These inert, glass-encased microchips are encoded with alphanumeric labels that identify specific mussels. The tags are located and read with a hand reader that looks much like a metal detector. Dots of glue are placed on both sides of every mussel shell, so even if the tags or telemetry devices fall off, hopefully the glue dot will remain as an identifying feature. The color of the glue dots can be changed to record the year, class and species of mussels released. Mussel Tagging

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