Science Partnership between USGS and Confederated Tribes of the Umatilla Indian Reservation to Support Conservation of Freshwater Mussels
Western Pearlshell (Margaritifera falcata) is a native mussel species of conservation concern in the Pacific Northwest region of North America. This species is of cultural importance to the Confederated Tribes of the Umatilla Indian Reservation (CTUIR). The current project is a collaboration between the USGS Columbia Environmental Research Center (CERC), the CTUIR, and USFWS to better understand the natural history of M. falcata to support reintroduction in Tribal watersheds. This effort supports the CTUIR Fisheries Program mission of protecting, conserving, and restoring native aquatic populations and habitats. More broadly, the work supports the First Foods management approach, which prioritizes traditional and historically significant foods that contribute to the continuity of the Tribe’s culture.
The Issue:
M. falcata mussels have been historically difficult to culture. Previous efforts to grow out M. falcata juveniles in a laboratory setting have been successful but showed low survival.
Addressing the issue:
Our objective was to optimize feeding to improve survival and maintain good growth rates during laboratory culture of Western Pearlshell.

- Juvenile mussels were cultured in a pulsed flow-through auto feeding system previously developed at CERC ) for five months.
- All mussels were fed the same algal mixture that is prepared by adding Nanno 3600® and Shellfish Diet 1800® to water to maintain optimum concentrations in the culture beakers.
- Feeding treatment 1: Algal mixture was prepared with CERC well water.
- Feeding treatment 2: Algal mixture was prepared with CERC pond water to add additional nutrients.
- Approximately 50 newly transformed (<30-day old) M. falcata were impartially stocked into each of 16 replicate beakers per treatment.
- Mussel survival in every replicate beaker was determined once every two weeks and a subset of mussels in each replicate were randomly selected and photographed for shell length measurements using digital image analysis.
Results/Future Results:
Mean survival was ≥ 89% in the two treatments over the 5-month culture period. Mussels grew substantially in both treatments. The increase in shell length of mussels in each feeding treatment was consistent over time. Mussels fed the algal mixture prepared with pond water had a slightly higher growth rate than those fed the mixture prepared with well water. Final size varied widely, with some individuals up to 5 times larger than others.
The pulsed flow-through auto-feeding system is an effective means to grow out juvenile M. falcata. These results will help CTUIR and other propagation facilities to increase the production of high-quality freshwater mussels for reintroduction trials and restoration.
The CTUIR and USGS partnership plans include expansion into other important western species such as Western Ridged mussel (Gonidea angulata).

Return to Fish and Invertebrate Toxicology
Pulsed flow-through auto-feeding beaker systems for the laboratory culture of juvenile freshwater mussels
Western Pearlshell (Margaritifera falcata) is a native mussel species of conservation concern in the Pacific Northwest region of North America. This species is of cultural importance to the Confederated Tribes of the Umatilla Indian Reservation (CTUIR). The current project is a collaboration between the USGS Columbia Environmental Research Center (CERC), the CTUIR, and USFWS to better understand the natural history of M. falcata to support reintroduction in Tribal watersheds. This effort supports the CTUIR Fisheries Program mission of protecting, conserving, and restoring native aquatic populations and habitats. More broadly, the work supports the First Foods management approach, which prioritizes traditional and historically significant foods that contribute to the continuity of the Tribe’s culture.
The Issue:
M. falcata mussels have been historically difficult to culture. Previous efforts to grow out M. falcata juveniles in a laboratory setting have been successful but showed low survival.
Addressing the issue:
Our objective was to optimize feeding to improve survival and maintain good growth rates during laboratory culture of Western Pearlshell.

- Juvenile mussels were cultured in a pulsed flow-through auto feeding system previously developed at CERC ) for five months.
- All mussels were fed the same algal mixture that is prepared by adding Nanno 3600® and Shellfish Diet 1800® to water to maintain optimum concentrations in the culture beakers.
- Feeding treatment 1: Algal mixture was prepared with CERC well water.
- Feeding treatment 2: Algal mixture was prepared with CERC pond water to add additional nutrients.
- Approximately 50 newly transformed (<30-day old) M. falcata were impartially stocked into each of 16 replicate beakers per treatment.
- Mussel survival in every replicate beaker was determined once every two weeks and a subset of mussels in each replicate were randomly selected and photographed for shell length measurements using digital image analysis.
Results/Future Results:
Mean survival was ≥ 89% in the two treatments over the 5-month culture period. Mussels grew substantially in both treatments. The increase in shell length of mussels in each feeding treatment was consistent over time. Mussels fed the algal mixture prepared with pond water had a slightly higher growth rate than those fed the mixture prepared with well water. Final size varied widely, with some individuals up to 5 times larger than others.
The pulsed flow-through auto-feeding system is an effective means to grow out juvenile M. falcata. These results will help CTUIR and other propagation facilities to increase the production of high-quality freshwater mussels for reintroduction trials and restoration.
The CTUIR and USGS partnership plans include expansion into other important western species such as Western Ridged mussel (Gonidea angulata).

Return to Fish and Invertebrate Toxicology