Groton — Eight monitoring buoys placed in the Thames River by a Navy contractor last month will be collecting data on endangered Atlantic sturgeon and other species, part of a fish and marine mammal survey in preparation for a pier-reconstruction project at the Naval Submarine Base.

Four of the green buoys are located north of the base, two are just offshore from the base and the other two are near the mouth of the river. The buoys bear labels reading “U.S. Navy Property. Do Not Disturb,” along with contact information for Tracey McKenzie, natural resource manager at the base.

“Any tagged species will be picked up on the receivers,” she said Thursday.

McKenzie said the environmental services firm Tetra Tech has been hired to conduct the monitoring, collecting data from the monitors under a $200,000 contract over the next two years. The company also will do visual surveillance of harbor and gray seals in the river and near the base as part of the project.

The monitoring is being done as part of environmental assessments required for the planned demolition of Pier 32 and replacement with a wider, longer pier for Virginia-class submarines. The project, planned for 2019, will include dredging of the navigation channel in the river, she said.

Chris Zendan, public affairs officer for the sub base, said the monitoring will take place over the next two years.

“While we are certainly interested in the possibility of identifying tagged Atlantic sturgeon, we are not exclusively conducting this effort focusing on sturgeon or seals,” he said.

However, any findings of Atlantic sturgeon using the river will be of particular interest to the Navy because of their status as an endangered species, which affords them greater protection. During earlier monitoring in 2015, a 2- to 3-year-old tagged sturgeon was found swimming in the river near the sub base. The sturgeon had an electronic tag implanted by a researcher on Long Island.

The National Oceanic and Atmospheric Administration’s Greater Atlantic Fisheries Office has been contacted by the Navy about the planned pier project, said John Ewald, spokesman for NOAA. The agency is responsible for enforcing Endangered Species Act provisions on marine animals, as well as the Marine Mammal Protection Act that prohibits the killing or harassment of seals without a permit.

Ewald said new approaches announced last month to preventing harmful noise impacts to marine life will not affect the Navy’s monitoring work but may alter the pier demolition and construction project in the future. The new Ocean Noise Strategy is intended to better address the impacts of ocean noise on protected species, he said.

McKenzie said if sturgeon and seals are found through the monitoring, the Navy will work with the National Marine Fisheries Service, a division of NOAA, to determine how to lessen impacts of the construction work on these species. The Navy could be required to keep noise levels from pile driving and other work below certain thresholds, install equipment to contain noise or to stop work during certain times of the year critical for spawning or other activities.

“It won’t affect our mission,” she said. “It may add process and it may add time or affect construction schedules.”

j.benson@theday.com