Fish Community Monitoring

River and Stream Fish Community Monitoring

biologists measure fish

Each year fish biologists monitor fish populations in selected waters across the state in order to maintain a robust data set. Long term monitoring helps to identify changes in fish communities due to landuse, water diversions, and natural events such as floods, droughts, increasing water temperatures, and in some streams, recreational fisheries management actions. Data for many of these sample events are available on the CT ECO Fish Community Data Viewer.

One such project was to re-visit sites that were sampled during the 1988-1995 statewide stream survey project. Phase one of this resampling focused on the occurrence of wild brook trout. To evaluate change statewide, 107 sites out of the 585 initial sites where at least one wild brook trout was observed were selected at random. Following two summers (2018-2019) of field data collection we observed wild brook trout were still present at 68 of the 107 sites (39 sites wild brook trout were not observed). Phase two involves identification of common variables for this network of sites to inform management actions. This initial analysis is available as a report and as a presentation.

Statewide Stream Survey Project (1988-1995) a map of stream survey sample locations

A comprehensive survey of Connecticut's rivers and streams was completed over a seven year period between 1988 and 1995. Data on fish populations, physical habitat, and water chemistry were collected from 978 sites on 800 streams. The objectives were to 1) quantify the state's coldwater and warmwater fisheries resources, 2) compile a database which allows timely and accurate completion of environmental permitting and reviews, 3) develop models which accurately predict species composition and biomass in Connecticut streams, 4) make this information available to the public, and 5) provide the information necessary to develop a trout management plan for Connecticut streams.

The following links are to the various stream survey reports and fish community data available online:

CT ECO Fish Community Viewer (interactive map with data)

Final Report Statewide Stream Survey Project

Upper Housatonic River Basin Report

Lower Housatonic River Basin Report

Upper Connecticut River Basin and Farmington River Basin Report

Lower Connecticut River Basin Report

Upper Thames River Basin Report

Lower Thames River Basin and Eastern Coastal Basin Report

Western and Central Coastal Basins Report