Aquatic Wildlife Conservation Center
Located near Marion, Virginia, the Aquatic Wildlife Conservation Center (AWCC) was established in 1998 by the Virginia Department of Game and Inland Fisheries to actively recover Virginia's freshwater mussels. Over the past ten years, 2,618,500 juvenile mussels of 24 species have been propagated, with over 638,000 being released back into the wild.
The AWCC has also begun work with other aquatic wildlife, including the state-threatened spiny riversnail (Io fluvialis) and the eastern hellbender (Cryptobranchus alleganiensis alleganiensis — learn more). Between 2005 and 2008, 10,960 juvenile spiny riversnails from the Clinch and Powell rivers have been released. In addition, 32 juvenile eastern hellbenders have been raised from eggs.
Mussel Production Systems at AWCC
Recirculating systems are used at AWCC to propagate freshwater mussels. These systems feature tanks with individual inflow and outflow. Host fish infected with larval mussels are kept in tanks. Out-flowing water is filtered to collect juveniles after they fall off the host fish and then is filtered and pumped back through the system. Two kinds of systems are used: one for larger fish (e.g. largemouth bass or rock bass) and one for smaller fish (e.g. darters or sculpin). These systems are designed to allow propagation of more than one species per system at a time.
Juvenile Rearing
Juvenile mussels are counted and measured when they drop off the host fish. They are then placed in a rearing system to allow them to grow large enough to increase their chances of survival in the wild. The rearing systems include an array of 5-liter tanks that are supplied with filtered water from the river. The water is filtered to eliminate predators that might consume small juveniles. Another rearing system has recently been added using re-circulated water, allowing staff to control the system's water temperature and food content. Each tank is also fitted with a filter to catch any juveniles that might escape between sampling events.
The AWCC is constantly developing and testing new systems and methods of rearing juvenile mussels in an effort to reach optimum growth and survival rates.
Featured Species: Spiny riversnail (Io fluvialis)
The spiny riversnail, a state threatened species, is a gill-breathing freshwater snail found in the Clinch, Powell and Holston river systems of southwest Virginia and northeast Tennessee. An adult spiny riversnail can live 15 years and grow to lengths of about 50 cm, making it one of the largest species of aquatic snails in North America. Limiting factors for this threatened species include impoundments, dams and declining water quality.
Spiny riversnails range in color from brown to olive green. The inside of their shell is sometimes marked by purple bands. The snails get their name from large, armored spines that grow on their shell. However, some populations lack spines. Spiny riversnails feed on algae and organic debris found on river rocks, making them an important factor in maintaining good water quality.
Females lay eggs in the spring when water temperatures begin to reach 60° F. Eggs are laid in whorls or lines on smooth surfaces and can be found on rocks and in empty mussel shells. Eggs are very small (0.35 mm or 0.01 inches) and are slate gray to deep purple in color, hatching in 15-20 days.
Between 2005 and 2008, nearly 11,000 spiny riversnails have been produced at AWCC and released into the Clinch and Powell rivers. These have ranged in age from 6 months to 2 years old. The spiny riversnail reached maturity at AWCC after 2 years.