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: Fluted kidneyshell (Ptychobranchus subtentum)
The fluted kidneyshell is a large freshwater mussel with adults measuring between 80-130 mm (3-5 inches). Shell color ranges from yellow-green to brown and is marked with wide green rays. This species is not sexually dimorphic, meaning males and females cannot be differentiated by looking at the shell. The interior of the shell, called nacre, can range from white to pink or salmon in color.
The fluted kidneyshell is a longterm brooder, meaning animals spawn in the summer and larvae are held over winter (October - July). Females package larvae (also called glochidia) in conglutinates that look like blackfly pupae. Once conglutinates are released (believed to be triggered by water temperature), they snag on rocks on the stream bottom. Each packet contains several hundred larvae. When fish feed on the packets, they burst open, releasing larvae in the fish's mouth. Host fish include redline darters and fantail darters.
The fluted kidneyshell is currently a candidate for federal listing. On a state level, the species is listed as imperiled in Virginia and Tennessee, and critically imperiled in Kentucky.
At AWCC the fluted kidneyshell is propagated using redline darters. In 2009, over 41,000 juveniles were produced. Several thousand are currently being held at AWCC for grow-out before being released in the Clinch and North Fork Holston rivers.
