December 19, 2017 — Communication among cod comes in the form of vocalized grunts. And for haddock, it’s knocks.

Now it appears that increasing traffic noise from large vessels in the Gulf of Maine may be reducing the range of communication for the two species of Atlantic groundfish, according to research by NOAA Fisheries scientists.

The study, undertaken by scientists from NOAA Fisheries’ Northeast Fisheries Science Center and published in Scientific Reports, said the decline in the ability to communicate may generate widespread changes in the species’ “daily behavior, feeding, mating, and socializing during critical biological periods for these commercially and ecologically important fish.”

Cod, for instance, vocalize to attract mates and listen for predators and “not hearing those signals could potentially reduce reproductive success and survival,” according to the study.

Using bottom-mounted instruments to record the cod grunts and haddock knocks, scientists spent three months monitoring the sounds made by the two species at three separate spawning sites within the Gulf of Maine — two inside Stellwagen Bank National Marine Sanctuary and one inshore south of Cape Ann.

“We looked at the hourly variation in ambient sound pressure levels and then estimated effective vocalization ranges at all three sites known to support spawning activity in the Gulf of Maine cod and haddock stocks,” said Jenni Stanley, a marine research scientist and lead author of the study. “Both fluctuated dramatically during the study.”

The variations of the sound levels, she said, appear to be driven by the activities of large vessels.

Read the full story at the Gloucester Times