Nebraskaland

Mussel Propagation One Nebraska species in danger is the plain pocketbook (Lampsilis cardium). Its population is deemed imperiled by rarity and vulnerability to extirpation because of its decreased distribution in the 20th century. Work with the plain pocketbook started in 2014 in Nebraska by Dean Rosenthal, a veteran biologist who was recently named the Commission's division administrator for fisheries. Rosenthal attended a presentation on mussel propagation at a national workshop and he wanted to see if it would work to help declining populations in Nebraska. "It is our responsibility to manage the entire ecosystem of our aquatic habitats, not just the sport fish," said Rosenthal. "Mussels serve as an indicator species to indicate the health of our aquatic environments. They cannot just swim away when there is poor water quality. We have seen a decline in the mussel populations across the state, not only in numbers of individuals but in species diversity. We have reached a point in many of our streams that if we don't step in and attempt to help these species recover and re-establish themselves we will continue to lose these species from our environment." Rosenthal took the mussel rearing program to the North Platte State Fish Hatchery, where Bryan Sweet, fish and wildlife program manager, and Ted Bartels, fish culturist/supervisor, along with other Commission biologists, started to learn about mussel propagation. Mussels collected from the Mississippi River by staff of the Genoa National Fish Hatchery in Genoa, Wisconsin, were used to get the team accustomed to the process, during which they developed new techniques that had not been considered by leading mussel researchers. In 2015, seven fertilized female plain pocketbooks were collected from the Elkhorn River by Joe Cassidy, fish culturist/supervisor, and brought to North Platte where the mussel rearing project moved into full gear. In the wild, a plain pocketbook male will release a structure called a spermatozeugmata, which resembles a bubble of sperm, into the water. This bubble aids in the survival of the sperm. As it floats downstream, the female will siphon the sperm from the water, flushing it over her eggs to fertilize them. These eggs develop into parasitic larvae called glochidia that are housed within the gills of the female. To survive, these larvae need a host fish to continue their life cycle. In the genus Lampsilis, female mussels have a mantle flap that extends beyond their shell and looks Ted Bartels (left) and Bryan Sweet count and measure juvenile mussels before placing them in baskets that will be submerged into hatchery ponds. The mussels will be over-wintered in the ponds before they are tagged and released. 44 NEBRASKAland • APRIL 2017

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