Atlantic Salmon Thermal Habitat and Water Quality

Water Temperature in Atlantic Salmon Rivers

The Maine DMR monitors water temperature in approximately 20 sea-run Atlantic salmon drainages across the state of Maine. The extensive network of inexpensive, highly accurate data loggers provides over 1,000,000 temperature measurements annually.  The data gives the department the ability to evaluate the extent to which water temperature limits growth and survival of juvenile Atlantic salmon in habitat reaches thoughout these 20 rivers and helps the Commission to prioritize river reaches for fry and parr stocking.  For example, the Narraguagus River in the Route 9 area of Beddington constitutes a large portion of the overall habitat available to juvenile Atlantic salmon in this particular river.  Temperature monitoring in this section has shown it to be at times susceptible to critically high temperatures during summer heat waves.  However, nighttime lows usually provides juvenile salmon with an important recovery period that allows them to survive through these warm spells.  The 24-hour temperature coverage allows us a more complete picture of what is happening to fish.

Water Quality in Atlantic Salmon Rivers

In 2003, the Atlantic Salmon Commission began collaborating with the Senator George J. Mitchell Center for Environmental and Watershed Research at the University of Maine (GMC) in creating seasonal snapshots of pH related water chemistry in Maine salmon rivers.  Water samples were collected in spring, summer and fall by staff from the ASC, GMC, NOAA, DEP and volunteers from watershed councils from approximately 70 sites throughout 13 Maine Atlantic salmon rivers including: the Dennys, Machias, East Machias, Narraguagus, Pleasant, Ducktrap, Cove Brook, Kennebec and Sheepscot rivers. In addition, a more intensive study investigating the effects of land use on water chemistry is being conducted in tributaries of the Union (relatively undisturbed) and the Narraguagus Rivers (managed forest land).  These surveys document that rivers east of the Penobscot River have lower pH and alkalinity than rivers to the west, and that storm events have the potential to lower the pH in the eastern rivers to levels where it may be affecting the survival of out-migrating Atlantic salmon smolts.