January 8, 2018 — NOAA scientists studying sounds made by Atlantic cod and haddock at spawning sites in the Gulf of Maine have found that vessel traffic noise is reducing the distance over which these animals can communicate with each other.

As a result, daily behavior, feeding, mating, and socializing during critical biological periods for these commercially and ecologically important fish may be altered, according to a study published in Nature Scientific Reports.

Three sites in Massachusetts Bay included two inside Stellwagen Bank National Marine Sanctuary, a region well known to whale-watchers from the Cape because whales feed in the plankton-rich bank, and one inshore south of Cape Ann. All were monitored for three months by researchers at the Northeast Fisheries Science Center (NEFSC) laboratory in Woods Hole, and at the sanctuary offices in Scituate.

Vocalizations, such as Atlantic cod grunts and haddock knocks, were recorded by bottom-mounted instruments at each site during spawning in winter and spring.

“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 for Gulf of Maine cod and haddock stocks,” said Jenni Stanley, a marine research scientist in the passive acoustics group at the NEFSC and SBNMS and lead author of the study.

“Both fluctuated dramatically during the study. The sound levels appear to be largely driven by large vessel activity, and we found a signification positive correlation with the number of Automatic Identification System (AIS) tracked vessels at two of the three sites.”

AIS is an automatic tracking system, used on ships and by vessel traffic services. It provides information on a vessel, such as its unique identification number, position, course and speed, which can be displayed on a shipboard radar or electronic chart display.

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