WASHINGTON (CN) – Protecting five Texas freshwater mussel species is warranted but precluded by higher priority Endangered Species Act listing actions, according to the U.S. Fish and Wildlife Service.
Instead of being listed as threatened or endangered, the Texas fatmucket, golden orb, smooth pimpleback, Texas pimpleback, and Texas fawnsfoot have been added to the candidate species list joining 244 other species whose status the agency has previously determined warrant protection under the act.
The list is ranked by threat level and every year a selection of the most imperiled species are selected for protection. However new petitions for protection are considered on an equal footing with candidate species so being on the list does not guarantee a timely listing.
The number of live specimens found for all five species have been in decline and they are now present in only a fraction of the river systems where they were once abundant.
The primary reason for the decline, according to WildEarth Guardians, which filed listing petition for these and four other mussel species, is habitat loss and degradation due to the impoundment of rivers by dams.
Dams block the movement of host fish that serve as live taxis for freshwater mussels, carrying them to new breeding and feeding grounds. As a result, genetic diversity declines and the range of the species declines as isolated populations can be easily wiped out by heat, trampling by humans and livestock or predation.