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The lower Hudson River Estuary is a dynamic region that supports a wide range of fish species. Hudson River Park uses two year-round survey methods to monitor the presence of fish in the Park’s Estuarine Sanctuary waters: a fish collection survey and an environmental DNA study.

The fish collection survey uses crab pots and minnow traps to catch and  hold fish, which are identified, measured and returned to the River undisturbed. This study was begun by the original River Project in 1988, and has been continuously monitored for more than three decades. This study has caught and identified 52 species of fish in the lower Hudson River to date. 

The environmental DNA, or eDNA, study represents a newer survey technique to measure genetic material from the sloughed cells and feces of living marine organisms in our local waters. Sampling began in 2019 as Hudson River Park and Cold Spring Harbor Lab initially partnered to explore the effectiveness of eDNA as an educational tool and method to gather data on fish biodiversity in the Estuarine Sanctuary. These water samples are processed to isolate and extract the DNA present within the water and can be used to determine if particular species of fish are present within the sample.

Together, these two survey methods help build a more complete picture about the fish species that inhabit our waters year-round.

Reports & Data



Scientists collect and test samples of environmental DNA to study Hudson River Park local fish dynamics.

Environmental DNA is an emerging research method that studies DNA present in our local waterways to monitor fish biodiversity and population dynamics. HRPK has partnered with the Cold Spring Harbor Laboratory from 2019–2021 to analyze DNA in the Park’s waters.

Scientists collect samples of environmental DNA to study Hudson River Park local fish dynamics.

Park scientists study eDNA by regularly collecting one-liter water samples from the River at various locations. These water samples are then filtered to collect the eDNA fragments for analysis.