Fine-Scale Positioning System Proves Effective for Monitoring Fish Behavior at Wind Farms

As offshore renewable energy developments such as wind farms, tidal and wave technologies expand rapidly, so do concerns about their ecological impacts on marine life.

Lead author Dr. Oliver Shipley and PI Dr. Michael Frisk of Stonybrook University, along with a team of researchers from several institutions, evaluated the effectiveness of fine-scale positioning to monitor fish behavior under challenging temperate conditions at a wind farm development area.

Challenge

While renewable offshore energy production offers a promising means to address climate change, the ecological impacts – such as sediment disturbance, toxicant release, food chain disruption, and habitat alteration – associated with construction, operation, and eventual decommissioning of offshore structures can affect species and ecosystems in various ways.

One such concern is the electromagnetic fields (EMFs) generated by subsea cables that deliver power to shore from offshore structures, particularly wind farms. EMFs can potentially alter the behavior and movement of electrosensitive fish and marine mammals.

Mitigating these impacts is an important component of responsible offshore development. However, it requires detailed information on residency and behavioral patterns of aquatic animals at high spatial resolutions which are challenging to achieve in dynamic and harsh marine environments, such as the temperate Northwest Atlantic Ocean.

Solution

To address the challenge, the team deployed Innovasea’s fine-scale positioning system around a subsea power cable associated with the Ørsted South Fork Wind Farm in coastal waters off southern Long Island, New York. The objective was to validate the array’s ability to determine fine-scale behaviors of various marine species with diverse life histories.

The array consisted of 20 VR2AR acoustic receivers that recorded positions for 16 months from August 2021 to December 2022. A total of 201 fish across a range of species were surgically implanted with a V9, V13 or V16 transmitter depending on the size of the individual being tagged. Additional detection information collected by the Atlantic Cooperative Telemetry (ACT) network from another 59 tagged animals was acquired through data-sharing agreements.

Results

Findings suggest that the fine-scale positioning system effectively monitored behaviors across a variety of marine species at sub-meter resolution. Over the 16-month study period, 260 individuals spanning 17 different species were tracked within the array and provided 53,744 unique positions.

The positions also revealed that the system was effective in determining different behavioral patterns. Atlantic sturgeon and striped bass, for example, appeared to use the array as movement corridors, whereas clearnose and little skate exhibited higher residency.

Overall, the study demonstrated that Innovasea’s fine-scale positioning system is an effective tool for monitoring diverse fish behaviors in highly dynamic marine environments, and for addressing many ecological impact questions following the development of offshore structures.