Buying Time for Endangered Species
Mississippi river systems.
A total of four pallid sturgeon females have been spawned in two production years (1992 and 1997) at Blind Pony. Approximately 10,000 9-inch fingerlings were released back into the Missouri and Mississippi river systems from these four females. Blind Pony hatchery is currently being renovated to include a new sturgeon-rearing facility capable of raising up to 14,000 pallid sturgeons each year.
Blind Pony also raises the state-endangered lake sturgeon. However, the lake sturgeon are not spawned at the facility. Instead, the hatchery receives fertilized eggs from the state of Wisconsin. After the eggs are hatched, they are raised with the same techniques used for the pallid sturgeon. All of the lake sturgeon are tagged before release into the Missouri and Mississippi river systems.
Sampling efforts are now underway on the big rivers. These hatchery-produced fish are beginning to show up in fair numbers, and they are proving that efforts to reintroduce the two species of sturgeon are having an effect on the population.
It may be surprising to learn that most of the endangered species found in Missouri rivers are native mussels. Most mussel larvae are parasites of particular species of fish, which means that they cannot reproduce unless that fish species is present. Fortunately, this includes species such as bass and walleye that are produced routinely at hatcheries.
Since 1999, several mussel species have been raised through a combined effort between the state’s hatcheries, including Lost Valley and Chesapeake Hatcheries, and Missouri State University. The federally listed pink mucket, fat pocketbook and scaleshell are among several species being propagated and released. So far, over two million juvenile mussels have been released.
The requirements for successful mussel rearing include gravid female mussels (ones carrying larvae), suitable host fish and the proper equipment to hold the host fish and capture the juvenile mussels. The search for gravid females starts in early spring and continues into late summer.
Once the mussel and host fish are ready, the inoculation process takes place. The valves, or shell, of the female mussel are spread apart far enough to access the gills where the glochidia (mussel larvae) are held. A syringe is used to flush the gills and release the glochidia into a holding container. These larvae only range in size from 0.08 to 0.35 millimeters, so samples have to be counted with a microscope. The number collected from the mussel can range from a few thousand to several million,