Fat Threeridge (Amblema neislerii), Shinyrayed Pocketbook (Lampsilis subangulata), Gulf Moccasinshell (Medionidus penicillatus), Ochlockonee Moccasinshell (Medionidus simpsonianus), Oval Pigtoe (Pleurobema pyriforme), Chipola Slabshell (Elliptio chipolae

摘要

We do not recommend a change to the classification or priority ranking of any of the seven listed mussels. The seven species are highly restricted in distribution, occur in generally small subpopulations, and show little evidence of recovering from historical habitat losses without significant positive human intervention. The species and their habitats continue to be impacted by excessive sediment, channel instability, gravel mining, reduced water quality, developmental activities, water withdrawal, impoundments, and invasive species. Their limited distributions and small populations render them vulnerable to random natural or human-induced events such as droughts or spills. The degree of threat to the persistence of the five endangered species remains high (and moderate for the two threatened species), and the potential for recovery for all seven species remains low. While some progress has been made on achieving the recovery of these mussels, with the exception of range increases in the shinyrayed pocketbook, none of the subpopulation recovery criteria have been met for any of the seven species. Importantly, we do not yet understand how many subpopulations are necessary to ensure population viability, reduce isolation among populations, and increase the potential for genetic exchange. These data gaps were to be addressed in three specific recovery tasks; however, no progress has been made on these tasks. In addition, many of the listing/recovery criteria (threats) are not currently met. Water quality is not meeting designated use (CWA - Section 305(b)) and stream channels are not stable with intact riparian zones throughout the range of the seven species. Further, recent research indicates some numerical criteria for pollutants are not protective of early life stages of these mussels. Because all seven species continue to have reduced fragmented distribution and continued threats, the status of all seven species should remain unchanged.