Who Needs Flir? a Low Cost but Highly Sensitive Thermal Profile Method to Identify Cool Water Refugia in Downeast Maine Salmon Rivers

A water temperature profile method developed by Vaccaro and Maloy (USGS Report 2006-5136) was used to efficiently locate summer time cool water refugia for two stenothermic salmonids (Atlantic salmon and Brook Trout) that experience thermal limiting factors each summer.

This low cost methodology identifies both cooling and warming trends from 2 second interval sampling events. Data collection equipment is relatively inexpensive because only 1-2 people are needed and sampling equipment consists of a handheld GPS Unit and 3 highly sensitive temperature loggers (Solinst Inc.)

Surveys were completed between the hours of 10AM and 4PM to coincide with optimal thermal conditions.  Overall spatial coverage per day is dependent on stream gradient and habitat complexity.  In the Narraguagus River study area (Catchment=53-192 km², 0.1% gradient and poor canoeing conditions due to low water) we surveyed at a speed of 2.4km/hr covering between 7-11 km over 3-4.5 hours.   This equates to 5,400 – 8,100 data records per trip.

Data collected between each 2 second record was binned into 3 nominal criteria for visual inspection relating to a rate of change: 1) <0.001 °C= Decreasing, 2) -0.001 – 0.001 °C Stable and 3) >0.001 °C= Increasing.  Results will help prioritize restoration future projects.