A study by the University of Maryland indicates that new offshore wind farms being constructed on the Delaware-Maryland-Virginia coastal shelf could become a stopover spot for migrating Atlantic salmon and striped bass.
The development of offshore wind farms is a key component in the drive for renewable energy, but, like any large civil engineering project, their construction and operation involves some trade-offs. Whatever their benefits, such wind farms are potentially disruptive to local sea life. However, they can also be a potential new habitat, much like oil rigs and artificial reefs.
In order to try and mitigate problems while retaining the benefits, a number of studies have been carried out in the United States and Europe. As part of these efforts, the University of Maryland Center for Environmental Science study looked at the potential impact of wind farms on established migration patterns of salmon and striped bass passing through the relatively barren DelMarVa coastal shelf 17 to 26 mi (27 to 42 km) off the Ocean City, Maryland shoreline as they traverse from their breeding grounds to their feeding grounds.
In particular, the researchers wanted to find out how to minimize construction impact on the migrating fish and whether the farm site might create a new habitat where the fish might linger. To do this, they caught a sample of migratory salmon and striped bass in the area and, after recording their size, weight, and sex, the scientists surgically implanted acoustic tags to the fish and released them.
According to the team, the tags sent out an acoustic ping with a unique ID code and depth telemetry every few seconds, which was recorded by an array of 20 acoustic receivers in the Maryland Wind Energy Area. In all, 352 individual Atlantic sturgeon and 315 individual striped bass were tracked.
By measuring the migration habits of the fish, it was possible to determine that during the local summer, the fish were rare or absent, so it is possible to schedule construction when the loud noises generated will have the least impact.
They also found that the future offshore wind farm could act as a stop-over region for the migration – rather like motorists stopping for a rest and a bite to eat before resuming their journeys. However, more data needs to be gathered to determine the overall impact of the farms on fish migration in the northwest Atlantic Ocean, which could have wider applications for other parts of the world with similar migrations and wind farms.
"Scientists have learned a lot about the Atlantic sturgeon and striped bass’ seasonal patterns of habitat selection within spawning rivers, estuaries, and shelf foraging habitats," says study author Ellie Rothermel. "During these times, we know where the fish are likely to be and when to expect them there, but information on the location and timing of key coastal migrations is limited. Coastal waters have been largely inaccessible to scientists. Our study uses acoustic telemetry to understand the critical migratory periods in the lives of these fish species."
The research was published in PlosONE.
Source: University of Maryland