The mussel program at Inks Dam National Fish Hatchery is continuing to apply new rearing methods for freshwater mussels every year. A goal for this coming season was the installation of a living stream. There are several factors that contribute to the growth of juvenile mussels and many of these are absent in tanks in a research lab. A living stream would help provide a more natural environment in a research setting and include factors such as, natural sunlight and ambient temperature changes.
The artificial stream system was created by placing a 40-foot tank inside a decommissioned concrete raceway on hatchery grounds. The system was divided into four tiered sections and receives water directly from Inks Lake, providing food for all invertebrates that live in the tank. The system was also plumbed with partial recirculation, contributing constant flow and a closed system, if the need arises.
Each of the four tiered sections contain different substrates meant for specific purposes. The top portion of the raceway is about four feet deep and consists of a layer of sand. This was designed for holding host fish infested with mussels. The sandy bottom provides a natural environment for the juveniles to live and grow once they drop-off the fish’s gills. The middle two sections are much shallower and are meant for mature mussels, such as our, to burrow in and remain on-site during the season in which they are gravid. One of these two middle sections has a base of granite gravel and the other has pea gravel; as some mussel species prefer a courser substrate to live in. The fourth and final section was designed for juvenile mussels that were propagated in the lab and are ready to transition into an outdoor system. Its bottom was covered with sand, as these tiny mussels need a much finer substrate to burrow. There are also species like the yellow sandshell, that prefer to live in a sandy bottom and can also be placed in this section.