Wednesday, February 28, 2024

Sonar camera allows Navy to study fish behaviors near worksite

Marine Biologists Cara Hotchkin and Scott Chappell at the Navy's work site near Little Creek base (Southside Daily photo/Courtesy of William Chappell and Fleet Forces Command)
Marine Biologists Cara Hotchkin and Scott Chappell at the Navy’s work site near Little Creek base (Southside Daily photo/Courtesy of William Chappell and Fleet Forces Command)

VIRGINIA BEACH — Human beings it seems are, by nature, somewhat unconcerned about the world around them. Likely it’s a by-product of being at the top of the food chain for a few millennia.

But human activity isn’t without its consequences, and for the Navy in Hampton Roads the goal is to be good stewards of the environment around them.

“We have a large presence and a significant responsibility to take care of the environment,” said Mike Andrews, Public Affairs and Communications Officer with Naval Facilities Engineering Command.

Andrews said they were asked to launch a study that would gauge how fish populations near an elevated causeway being constructed at the Joint Expeditionary Base Little Creek by the engineers, for Fleet Forces Command training purposes, might be affected by noise and activity around the site.

So Naval Facilities Engineering brought in marine biologists Cara Hotchkin and Scott Chappell to have a look.

“The driving of pilings produces sound waves through the water,” said Chappell, who also identifies himself as a fisheries habitat biologist. “Those sound waves are capable of injuring or killing fish if they are very close to the pile driving, 100 feet or closer.”

The muddy water of the Chesapeake Bay makes visual studies impossible, so Chappell and Hotchkin are using an Adaptive Resolution Imaging Sonar (ARIS) acoustic camera. The device, Chappell said, works much like a dolphin’s built-in sonar or a man-made fish-finder, by sending out very low intensity sound beams that reflect off underwater objects.

The ARIS sends out a wedge-shaped beam that can cover an area of about 250 square feet and within that wedge can detect the shape and movement of fish within it.

He said they’ve found that the number of fish near this particular pile-driving site is low and that no breeding habitats are being impacted.

The sounds from the pile-driving can cause changes in fish behaviors such as more “stressful interactions” with other fish or with their environment, and “defensive maneuvers or alerted distraction” that are not their routine.

“The effect of sound on fish behavior is an area of ongoing scientific research and this (project) represents the only one of its kind using high resolution sonar to evaluate fish behavior in the muddy waters of a bay environment,” Chappell said.

However, the study won’t be able to determine if the sounds and any unusual behaviors they produce will directly impact the viability of species in the area.

The location of the work is on a beach and sandy nearshore environment that is without structures such as oyster reefs, seagrass beds, artificial reefs, or shipwrecks, which tend to attract more fish.

The Adaptive Resolution Imaging Sonar (ARIS) acoustic camera (Southside Daily photo/Courtesy of William Chappell, Fleet Forces Command, and Blue Land Media)
The Adaptive Resolution Imaging Sonar (ARIS) acoustic camera (Southside Daily photo/Courtesy of William Chappell, Fleet Forces Command, and Blue Land Media)

“The fish observed to-date at the Little Creek training location have been mostly small schooling species and crabs in the deeper water a little further offshore,” Chappell said.

However, he said it was possible that the endangered Atlantic sturgeon could be present in the vicinity of the work, but that they would need to be very close to active pile-driving to suffer any potential injury.

For information on the Navy’s environmental efforts, visit their YouTube channel.

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