The brook trout is the only trout species native to West Virginia streams. And just like the state it thrives in, it’s quite a sight to behold. The trout has a dark green back with small markings, bluish sides and a pink belly. Its sides are covered in yellow and red dots and its fins are orange-red with a white strip on the front.

Unfortunately, West Virginia’s natural choice for a state fish is declining. Changes in land use, increasing water temperature and loss of streamside canopy and shade have caused populations to dwindle.

Our Role

Freshwater Institute staff noticed Rockymarsh Run, a local stream that flows next to their facility, has the correct water temperature and environmental conditions to support brook trout. However, the stream was empty of the native fish, suggesting other variables could be partly responsible for the decline of brook trout. A conversation with WV DNR biologists theorized that calcium precipitate could be having a negative effect on juvenile brook trout.

Calcium precipitate, also known as marl, is common to hardwater streams. However, calcium ions only remain in solution when water pH is low or slightly acidic. When hard water is aerated, the pH shifts upward and calcium precipitates out of solution, forming a powdery silt that could cover and potentially suffocate brook trout eggs and young fish.

An experiment was developed to test the hypothesis. Three very different water types that are common to Rockymarsh Run were created in the Freshwater Institute's new research facilities for use in the trial, including a raw springwater condition with low pH, a lightly aerated water with mid-range pH, and a continuously aerated treatment with high pH and obvious calcium precipitate. Brook trout eggs from Virginia's Paint Bank Fish Hatchery were obtained and stocked in replicate trays with fine gravel to simulate the substrate used in brook trout nests.

Juvenile brook trout survival was low across all treatments; however, not a single brook trout survived in the high pH and calcium precipitate condition. Calcium siltation covered the gravel and brook trout eggs in these containers.  

Why this project matters

While the results were not entirely conclusive, the findings supported the hypothesis that calcium or marl precipitate could be limiting brook trout survival in hardwater streams like Rockymarsh Run.

Additionally, Freshwater Institute staff continued to grow the remaining brook trout onsite. In mid-March, several hundred brook trout were picked up by WV DNR and reintroduced into the local Opequon Creek with hopes that they continue to grow and thrive. The stocking was carried out in partnership with Shepherd University's Ichthyology class as a hands-on learning experience for local college students.

This synergistic project between the WV DNR and The Conservation Fund's Freshwater Institute resulted in positive outcomes that are aiding brook trout reintroduction efforts and contributing to successful conservation in West Virginia.