A Tale of Two Fishes

By Ryan Lowndes, Edward Kim, Jeff Kneebone

As 2024 comes to a close, the New England Aquarium’s Fisheries Science and Emerging Technologies (FSET) team at the Anderson Cabot Center for Ocean Life has been busy downloading the data from over 100 acoustic receivers that we deploy annually off the coast of Massachusetts to monitor tagged sea turtles, false albacore, sandbar sharks, and other commercially and recreationally important fish species. A large portion of those acoustic receivers is strategically placed in areas designated for offshore wind development with the goal of investigating how wind turbine construction and operation impact the movement and residency patterns of a wide array of species.

Two of the species we’re studying are black sea bass and tautog, which are bottom-dwelling fishes that tend to strongly associate with complex structures such as rocky reefs and shipwrecks. As the development of offshore wind farms in New England continues, there is concern among anglers that black sea bass and tautog seasonal spawning migrations from deeper, offshore waters to shallow, inshore waters could be disrupted by the creation of new structures, i.e., offshore wind turbines. Simply put, there is concern that structures created by offshore wind development will create appealing habitats that will keep the fish offshore and deter migration to inshore areas where they are more accessible to anglers. To investigate the theory behind these concerns, we began a study in December of 2022 to explore and understand the movement of black sea bass and tautog between offshore wind energy areas and nearshore locations before, during, and after wind turbine construction.

Diving into the data

Between 2022 and 2023, acoustic transmitters were surgically implanted in black sea bass and tautog, and their movements were monitored by our acoustic receiver array within the offshore wind areas in addition to a separate array we maintain within Nantucket Sound. To date, we have detected most of our tagged fishes at least once in our offshore receiver array and realized their movements tell a tale of homebodies and nomads. Our tagged black sea bass routinely made their seasonal migrations to and from the wind energy areas each year, spending the warmer months in spring and summer nearshore and moving offshore in fall and winter.

Our tagged tautog, on the other hand, were not quite so adventurous. Every single tautog was only detected at the receiver they were caught and tagged next to in the offshore area. This initially worried us—did none of the tautog survive following tagging? But rest assured, they all did! Tautog have a funny habit of tucking themselves in at night into a rocky crevasse or overhang, emerging in daylight to feed. So, we ran an additional analysis to compare daytime versus nighttime detections, and found that when the tautog went to bed, so did the recorded detections, the transmitters’ signals having been disrupted by the rocks the tautog surrounded themselves with.

We are also fortunate enough to receive data contributions from other researchers’ acoustic receiver arrays via the Atlantic Cooperative Telemetry (ACT) Network. Thanks to those additional detections, we now know that our black sea bass not only migrated inshore to Nantucket Sound, but also to nearshore Rhode Island, Long Island, and areas offshore New Jersey! One black sea bass was tagged in the offshore wind area south of Cape Cod in October of 2023, where it stayed until November before it left the area. It was then detected in April of 2024 in an offshore wind area off of New Jersey, and by June, had made it to the Nantucket Sound before finally returning to the same area it was originally tagged in September of 2024!

Despite these migratory patterns observed in black sea bass (and, to a lesser though more mysterious degree, the tautog), we still need more data to support our understanding of any potential influences of offshore wind development. The wind turbines are continuously under construction, and we are eager to examine data for the rest of 2024. Additionally, we hope to deploy more transmitters in black sea bass and tautog in the wind lease areas south of Cape Cod to add more individuals to the study to further support our research and shed some more light on the movements of these amazing fishes!

Special thanks to the ACT Network and the various owners of the arrays who provided data and made this work possible: Dr. Timothy Rowell at the National Oceanic and Atmospheric Administration (NOAA), Dr. Keith Dunton at Monmouth University, Brittney Scannell at Stonybrook University, Christopher Parkins and Eric Schneider at the Rhode Island Department of Environmental Management, and to Alison Frey at the University of Massachusetts Dartmouth School for Marine Science and Technology.