Using Molecular Ecology to Inform Hudson River Tributary Dam Removal Planning

Dr. Liam Zarri (Smithsonian National Zoo and Conservation Biology Institute)

Thursday, February 6 | 2:30PM ET | Online and Open to the Public

Riverine fish conservation commonly focuses on restoring connectivity for migratory fishes by removing old dams that fragment otherwise large swaths of free-flowing river. For non-migratory fishes, the removal of these dams may not elicit the same positive response because they can complete their lifecycle in small stretches of river. Many non-migratory fishes exhibit a bell curve shaped distribution in density: low at their upstream and downstream extents and high at their core. Findings of a recent study on redbreast sunfish (Leopomis auritus) in tributaries to the lower Hudson River done by Dr. Zarri and their team suggest removal of dams at the upstream fringes of a non-migratory species’ within-basin range could alleviate a greater degree of genetic differentiation than the removal of dams at the core of their distribution. The conservation implications of upstream barriers for imperiled non-migratory taxa have potentially been overlooked and may lend more options to managers balancing the complex social, financial, and ecological criteria guiding the dam removal decision-making process.

Using this as a case study, Dr. Zarri’s presentation will focus on (1) the utility of molecular tools for freshwater conservation planning and (2) conservation genetic perspective on riverine dams, such as impact by small (pervasive) vs. large (more rare) dams on migratory and non-migratory fishes.

This event is part of 2025 Spring Seminar Series: Applied Water Research in New York State hosted by the New York State Water Resources Institute. The series runs on Thursdays from 2:30 - 3:30PM ET from January 23 - March 6, 2025.

The work presented was prepared for the NYS Water Resources Institute at Cornell University and the NYS Department of Environmental Conservation, with support from the NYS Environmental Protection Fund.