Ohio River Valley Ecosystem Team

by Bob Butler, FWS biologist, Asheville, NC
photos by Janet Butler, FWS biologist, Ohio River Islands NWR, WV

Mussel Blitzers

During the week of August 27-31, 2001, biologists from several Federal and State agencies and academia converged upon the Green River, in west-central Kentucky, to participate in a Amussel blitz.@ A blitz is a concerted effort by numerous biologists to intensively sample a few select under-sampled sites in a stream particularly for rare mussels.

The Green represents one of the ORVE=s highest priority focus areas for conservation efforts. The Nature Conservancy recognizes the upper Green River as a ACritical Watershed for Conservation@ in their Rivers of Life publication, ranking it fourth nationally in the number of fish and mussel species at risk. This project addresses Resource Priority 1 (mussel conservation), Action Strategy AA@ (obtain baseline inventory), in the ORVE Plan, and the proposal for the blitz was one of the top two projects ranked by the ORVE last year. The Asheville Field Office secured funding from Region 4 in FY 2001 to cover travel for most participants.

Inspecting the mussels

Fourteen representatives from the Service, U.S. Geological Survey, U.S. Environmental Protection Agency, Kentucky State Nature Preserves Commission, Tennessee Wildlife Resources Agency, Alabama Division of Wildlife and Freshwater Fisheries, and Western Kentucky University began arriving in Bowling Green the Sunday evening before the blitz was to begin. Unfortunately, unusually heavy rains also arrived that night in the central portion of the drainage where sampling efforts were taking place.

River conditions were marginal for sampling on Monday and Tuesday, but by Wednesday had deteriorated to zero visibility, hampering visual efforts to locate mussels. Nonetheless, results were promising.

Sampling at 6 main stem Green sites and 4 sites in its largest tributary, the Barren River, a total of 41 species were sampled. Thirty-five species were extant at sampling sites, as evidenced by live or fresh dead individuals. The remaining species were represented by relic shells only. Overall, 71 species are known from the Green River system, indicating that we found about 58% of the fauna during the blitz, about half of them live or fresh dead. Not bad considering the poor sampling conditions and relatively limited number of sites.

An important finding was the number of live young mussels located during sampling efforts. We found evidence of recent recruitment for 22 species, or 63% of the extant (e.g., live/fresh dead) species at sampling sites. The fact that nearly two-thirds of the fauna was experiencing some level of successful reproduction and recruitment was encouraging given the prevalence of declining mussel faunas in many Southeastern and Midwestern streams. Finding evidence of recent recruitment is therefore very important in assessing the relative health status of mussel populations. But it=s not easy locating tiny mussels in riverine habitats. A lot of movement of the substrate was necessary to find relatively few juveniles buried in slightly depositional shoal areas.

Three federally endangered species were found: the rough pigtoe (Pleurobema plenum), fanshell (Cyprogenia stegaria), and pink mucket (Lampsilis abrupta). Sampling efforts yielded a total of 60 live individuals of these 3 species. Relics of two other listed mussels, clubshell (Pleurobema clava) and ringpink (Obovaria retusa), were sampled. The Green represents the last known population of the ringpink (which was found live in 1999), and probably the best remaining population of the rough pigtoe. The only remaining population of clubshell south of the Ohio River is in the upper Green (above our sampling reach), while one of the three best populations of fanshell is found there. Also, 9 of 11 other species of concern mussels were found live during the blitz. The importance of the Green among streams in the Ohio River system is therefore critical for the recovery of a large suite of imperiled mussel species.

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