Brook trout eDNA Testing (Funded by HLCT)

The Old Swamp River (OSR), with flow coming from South Weymouth into Whitman's Pond, has been documented as a Cold Water Fishery by the Massachusetts Department of Fish and Game.  Brook trout (Salvelinus fontinalis) have historically been documented in the OSR through State surveys and local reports, as recently as 2019.  However, a stream survey in the summer of 2022 resulted in no signs of brook trout.  Brook trout require cold, clean, oxygenated water to survive and are becoming increasingly rare in the eastern part of Massachusetts. 

In the fall of 2022 the Conservation Commission applied for and received a small grant from the Hingham Land Conservation Trust (HLCT) Goodrich Environmental Research Grant to study presence/absence of brook trout in the OSR using eDNA analysis, and also monitoring temperature and dissolved oxygen. The project involves collecting water samples from multiple points in the OSR and sending them to the University of Maine to be tested for brook trout DNA in the environment (eDNA). The Commission is working with the Department of Ecological Restoration to remove a non-functioning dam (the SNUP dam) on the OSR (work expected FY25), giving an opportunity to study if the removal of the dam causes a resurgence in brook trout.

After conducting the spring 2023 sampling, the lab found no evidence of brook trout eDNA in OSR. Electroshock surveys were done in the OSR in July 2023, and the crew found no trout. Water temperature and dissolved oxygen data collected through July indicate that trout could survive in the river. Conservation staff will be collecting another round of eDNA samples in the fall of 2023 and will continue to monitor temperature and dissolved oxygen throughout the summer.

The Commission thanks HLCT for their support for this project.