Ship noise causes measurable stress in whales, according to a study that capitalized on an accidental experiment: the sharp drop in shipping traffic in the Bay of Fundy, Canada, in the days following the September 11, 2001, attacks.
The monitoring program was already up and running.
In July 2001, a research team from the New England Aquarium in Boston had begun a survey of the North Atlantic right whales that gather each summer in the Bay of Fundy to feed and nurse their young.
The method relied on trained dogs to locate whale feces floating on the water’s surface. Those samples provide reliable hormonal data on the animals’ physical condition.
At the same time, a separate team was recording the area’s low-frequency underwater sounds — the same acoustic band whales use to communicate, and the very band generated by cargo ships’ engines and propellers.
Neither team had set out to study the attacks. The timing turned a catastrophe into a research opportunity no one could ever have engineered.
Less Traffic, Less Noise, Less Stress
In the two days before September 11, nine ships passed through the bay. In the two days after, only three.
The effect on the underwater soundscape was immediate. Underwater noise fell by six decibels, with the sharpest reduction in frequencies below 150 hertz — the range that overlaps most directly with whale calls.
The researchers then compared those acoustic measurements with the glucocorticoid levels — stress-related hormones — found in the fecal samples collected before and after the attacks.
Hormone levels in 2001 were lower in the months after 9/11 than in the months before. The pattern did not repeat over the next four years of monitoring, which ruled out other seasonal or environmental explanations.
The findings were published in February 2012 in the journal Proceedings of the Royal Society B, offering the first evidence that ocean noise does not merely alter whale behavior — it also leaves a measurable physiological mark.
An Unplanned Experiment — and Its Limits
The research team itself admitted the conditions were far from ideal for drawing firm conclusions.
The analysis rested on just four days of acoustic recordings from before and after 9/11, plus a limited number of fecal samples.
A marine biologist at the University of St Andrews in Scotland publicly questioned whether the available data were enough to support the study’s conclusions. Together with colleagues, he proposed a more rigorous experimental design to properly test the finding.
Despite those objections, the study became a landmark in marine biology — not because it settled the question, but because it opened a line of inquiry that no one could have pursued without an extraordinary event: a near-total halt in shipping traffic.
The State of Right Whales in 2026
More than two decades later, the species remains critically endangered.
The most recent population estimate places North Atlantic right whales at around 380 individuals — an increase of roughly 20 since 2020, and the third consecutive year of upward movement. Of that total, only about 70 females are of reproductive age.
Collisions with vessels and entanglement in fishing gear remain the leading causes of death and injury.
In March 2026, NOAA Fisheries proposed a new rule on vessel speed limits in areas the whales are known to frequent.
Conservation organizations have been pushing for that measure for years, seeing it as the most effective tool available for cutting down ship strikes.
Underwater noise, by contrast, does not receive the same level of regulatory attention as vessel traffic and fishing gear.
The correlation found in the Bay of Fundy in 2001 is still cited as the first sign that quieter oceans, too, help keep whales alive.
