Population demographics for the federally endangered dwarf wedgemussel

Journal of Fish and Wildlife Management
By: , and 



The dwarf wedgemussel, Alasmidonta heterodon, is a federally endangered freshwater mussel species inhabiting several Atlantic Slope rivers. Studies on population demographics of this species are necessary for status assessment and directing recovery efforts. We conducted qualitative and quantitative surveys for dwarf wedgemussel in the mainstem Delaware River and in four of its tributaries (Big Flat Brook, Little Flat Brook, Neversink River, and Paulinskill River). Population range, relative abundance, size, size structure, and sex ratio were quantified within each river. Total dwarf wedgemussel population size for the surveyed rivers in the Delaware Basin was estimated to be 14,432 individuals (90% confidence limits, 7,961-26,161). Our results suggest that the historically robust Neversink River population has declined, but that this population persists and substantial populations remain in other tributaries. Sex ratios were generally female-biased, and small individuals (<10 mm) found in all rivers indicate recent recruitment. Dwarf wedgemussel was most often found at the surface of the sediment (not buried below) in shallow quadrats (<2.00 m) comprised of small substrate (sand in tributaries; cobble in the mainstem) and minimal aquatic macrophytes. Long-term monitoring, continued surveys for new populations, and assessments of reproductive success are needed to further understand dwarf wedgemussel viability within the Delaware River Basin.

Publication type Article
Publication Subtype Journal Article
Title Population demographics for the federally endangered dwarf wedgemussel
Series title Journal of Fish and Wildlife Management
DOI 10.3996/112014-JFWM-084
Volume 7
Issue 2
Year Published 2016
Language English
Publisher Scientific Journals
Contributing office(s) Leetown Science Center
Description 11 p.
First page 377
Last page 387
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