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Metrics for assessing freshwater fish in Narragansett Bay
Citation:
Rashleigh, B. AND E. Monroy. Metrics for assessing freshwater fish in Narragansett Bay. American Fisheries Society - Southern New England Chapter, New Bedford, Massachusetts, January 10, 2018.
Impact/Purpose:
The Narragansett Bay Estuary Program (NBEP) is one of 28 programs designated as estuaries of national significance under the National Estuary Program. The program helps protect and restore the water quality and ecological integrity of the Narragansett Bay itself as well as the million acre Narragansett Bay watershed, which is home to over 2 million residents from Rhode Island and Massachusetts. The NBEP works to assess conditions and trends in the watershed. Freshwater fish is one of the 24 indicators tracked by the NBEP.
Description:
Freshwater fish are ecologically important in stream ecosystems, and they provide significant value to humans. Historically, the streams and rivers of southern New England supported moderately diverse and abundant assemblages of native fishes. Currently, these habitats are impacted by both environmental change and land development, altering flow and increasing water temperature. As a result, the Narragansett Bay Estuary Program and its bi-state stakeholders are interested in assessing status and trends of freshwater fish in the watershed. Fish data collected by state environmental agencies was compiled for the watershed, and two metrics –relative abundance of fish species that prefer cold or cool water and/or flowing water – were calculated and summarized by HUC10 watersheds. In the Narragansett Bay watershed, the percent relative abundance of cold-coolwater and fluvial species ranged from 11% and 9% in the Palmer River, to 67% and 65% in the Upper Blackstone River, respectively. The pattern was largely driven by brook trout, a coldwater, fluvial species that is highly valued for conservation and recreation. Lower values of these metrics may be due to stressors or environmental setting (e.g., coastal streams); higher metric values are indicative of good environmental health, and their distribution within the study area provides a benchmark for future assessment. Future steps include calculating additional metrics and indices, and relating these to environmental factors and stressors.