Freshwater mussels can be negatively affected by heavy machinery during stream restoration projects, requiring mussels to be relocated from the project area to unaffected areas. We assessed recapture and survival of Western Pearlshell (Margaritifera falcata) relocated in Tincup Creek, Idaho before and after a stream restoration project. From 2018 to 2020, we searched 4,350 m of Tincup Creek before restoration and salvaged 1,213 Western Pearlshell. Mussels were measured, marked with shellfish tags, and relocated among 10 sites in previously restored reaches elsewhere in Tincup Creek. At the time of salvage, mussels ranged from 19 to 84 mm with 83% of the mussels ≥50 mm, and most mussels were found in run habitats (63%). We surveyed all sites for tagged mussels 1 to 3 yr after relocation. We recaptured tagged mussels at seven of the 10 sites, and the recapture rate was positively related to the number of relocated mussels and mussel size. Tag retention was high but varied among relocation years. Estimated survival after 3 yr was 69.9–87.4% at two sites, and detection probability was 60.3–62.9%. Estimated survival after 1 yr was 55.8–91.3% at four other sites. Survival was low at three sites, likely due to low numbers of relocated mussels or scarcity of suitable habitat, and survival decreased dramatically at one site (from 91.3% to 28.6%) in 2 consecutive years, likely due to beaver activity. Our results suggest that stream restoration created habitat suitable for Western Pearlshell, and relocation was a successful strategy for avoiding direct mortality associated with restoration activities.

Bear Creek is a tributary of the Tennessee River in northwestern Alabama and northeastern Mississippi. The watershed supports a diverse freshwater mussel assemblage including several species of conservation concern. We conducted a mussel survey at 55 sites in the Mississippi portions of Bear Creek and its largest tributary, Cedar Creek, during September and October 2020. We found a total of 30 species, of which 25 were represented by live individuals. The invasive Asian Clam, Corbicula fluminea, was widespread in the watershed, but we found no evidence of Zebra Mussel, Dreissena polymorpha. Notable species found live included two federally endangered species, Cumberlandian Combshell, Epioblasma brevidens and Slabside Pearlymussel, Pleuronaia dolabelloides; one federally threatened species, Rabbitsfoot, Theliderma cylindrica; and two state endangered species. In addition, we report the first documented occurrence of the Mountain Creekshell, Villosa vanuxemensis, in Mississippi. Mussel abundance and species richness were low at most sites in the watershed, but the upper portion of Bear Creek had the highest mussel abundance and species richness. We compare our results with previous surveys in the watershed and discuss conservation issues pertinent to the Bear Creek mussel fauna.

Most North American unionids are imperiled to some degree, including the Louisiana Pigtoe, Pleurobema riddellii, which is currently under review for listing under the U.S. Endangered Species Act. Understanding a species' population dynamics, including spatial and temporal variation in survival, density, recruitment, and population size, is vital for conservation, but this information is lacking for P. riddellii. We conducted a mark–recapture study to estimate apparent survival, density, recruitment, and population size of P. riddellii within a 25-m² area at three sites (75 m² total) in the Neches River, Texas from 2014 to 2019. We used the program MARK to evaluate POPAN models for estimating population parameters. We collected a total of 392 unique individuals of P. riddellii over the 5-yr period and the observed recapture rate averaged 55.6%. The most parsimonious POPAN model indicated that apparent survival varied temporally, the recapture rate varied temporally and spatially, and both the entry probability (recruitment) and population size varied spatially. Apparent survival averaged 83.3% ± 3.4% (SE)/yr, overall population size across the three sites was 429 individuals (overall density = 5.7/ m²), and recruitment averaged 6.3%/yr. High survival, relatively high density, the presence of recruitment, and the lack of temporal changes in population size suggest that these populations are stable. The presence of P. riddellii throughout a long section of the river, including localized patches of higher abundance, suggests that the total population size in the Neches River is relatively large and the river is a global stronghold for the species.

We studied population density, population size, and reproductive seasonality of the Phantom Tryonia, Tryonia cheatumi (Pilsbry, 1935). This endangered freshwater snail is found only in the San Solomon Spring system, a cienega, or karst-based, arid-land freshwater spring system, in western Texas, USA. We sampled populations at seven locations in the system seasonally over a 2-yr period. San Solomon Spring, the system's largest spring and modified into a swimming pool, had the largest population of T. cheatumi, with an estimated 49 million individuals and a mean density as high as 23,626 ± 39,030 (individuals/m² ± SD). There were seasonal differences in mean density (up to 25-fold) and median snail size at all sites, but consistent seasonal patterns of mean density or size were not observed. Median snail size among samples was not related to water temperature, and juveniles were present in most samples in all seasons. These results support continuous, aseasonal reproduction, as expected in thermally stable habitats, but differences in median size and mean density among seasons and sites suggest that other factors affect reproduction and seasonal variation in population size of T. cheatumi.

The Brook Floater (Alasmidonta varicosa) mussel is globally vulnerable and has disappeared from much of its historical range. Information on Brook Floater host fish use is needed for ecological and conservation purposes, but previous laboratory studies provide conflicting results. We evaluated host fish use by Brook Floater from populations in Massachusetts and Maine, USA. We conducted three experiments using a total of 10 fish species from six families, and we estimated glochidial attachment rate and juvenile metamorphosis rate. Across fish species, attachment ranged from 51.0% to 84.6% and metamorphosis ranged from 4.9% to 80.9%. Fish species and inoculation density (viable glochidia/mL) only weakly predicted attachment, and the number of glochidia that attached to fish did not affect metamorphosis rate. Juvenile metamorphosis was successful on all fish species tested, supporting evidence that Brook Floater is a host generalist. Fish species was an important factor in predicting metamorphosis rates in all experiments. The highest metamorphosis was on Slimy Sculpin (Cottus cognatus) (80.9% ± 2.6 SD) and Brook Trout (Salvelinus fontinalis) (71.6%), but metamorphosis on Brook Trout varied according to source and was lowest on hatchery-raised fish (12.8% ± 0.3 SD). These data contribute to our understanding of the life history of Brook Floater by identifying potential host fishes, and our results can inform propagation efforts for this species in the northeastern USA.