In one Adirondack Lake with marginal temperatures for brook trout, warm temperatures in some years resulted in complete failure to reproduce 13. These sublethal temperatures are accompanied by decreased feeding, growth, and reproduction 13,14. However, studies have observed physiological indicators of heat stress in temperatures as low as 21☌/68☏ 12. Brook trout begin to experience significant mortality as water temperatures approach 25☌/77☏ 11. Studies commonly have found that in streams where temperatures exceed 20☌/68☏ for extended periods, brook trout are either at low abundance, or are absent altogether 8,9,10. Indeed, modeling studies conducted in various parts of its range, including parts of Canada 6 and in the southern Appalachians 7, suggest large reductions in future distributions for brook trout. This species’ need for cold water implies that there is great potential for climate change to impact brook trout populations. In Massachusetts, wild, reproducing populations of brook trout have been greatly reduced and the majority that remain are restricted to isolated headwater streams 5. Because of their requirements for clean, cold water, brook trout have experienced extensive reductions in distribution and abundance because of habitat degradation 1. They generally do not tolerate extended periods of water temperatures above 20☌/68☏ 3, and the ideal temperature for growth and activity is between 12-19☌ (53.6-66.2☏) 4. Brook trout in Massachusetts are found primarily in streams that have cold, highly oxygenated water 3. Hideīrook trout are an economically important game species throughout their native range, which extends south in the Appalachians to Georgia 1 and north to the Atlantic drainages of Newfoundland, Labrador, and Quebec 2. Data are from a specialized run of Critical Linkages for coldwater streams conducted in 2017. Blue triangles are crossings that have not yet been assessed and the restoration potential is hypothetical.
Blue dots are crossings that have been assessed in the field and the potential for restoring aquatic passability is reliable. You can layer in locations for the top 5% and 10% of crossings with the highest restoration potential as estimated by landscape modeling.
BROOK TROUT PLUS
If these are not visible, use the plus sign to zoom in. Priority crossings for possible culvert replacement or retrofit on coldwater streams (summer mean temperature < 16C) are represented by blue dots and triangles. Estimates are from the USGS Conte Anadromous Fish Research Center, based on field surveys from Massachusetts DFW and agencies of nearby states CT, NH, VT, and NY. Stream characteristics that help predict whether Brook Trout can be found in each stream include stream size, average air temperature, nearby forest cover, and soil characteristics. Streams in blue are more likely to be inhabited by Brook Trout based on environmental conditions, while streams in yellow are less likely to have Brook Trout. The "Probability of Occurance" map displays current distribution of Brook Trout. Also displayed are streams where Brook Trout have been observed (by Mass DFW personnel) shown in orange. Map displays likely Brook Trout habitat in blue (coldwater fisheries resources streams).
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