Ship Noise is a Stressor For Right Whales
At Faunalytics, we have previously published information about studies that examine the impact of ship noise on whales. As human activity in the oceans has increased, so too has underwater noise. Ship noise is thought to have a negative impact on the sound-based communication and navigation of whales, but the extent of its effect on these animals is hard to quantify. One of the biggest hurdles that scientists face in the study of ship noise is a lack of control data – it is not possible to completely stop the noise from ships in order to understand how whales behave in its absence. To try to work around the problem, this study looks at the drop off in human ocean activity in the Bay of Fundy in the aftermath of September 11th 2001.
The researchers looked at ocean noise data from this time, as well as information from the subsequent four years, and compared it to measures of stress hormones found in whale faeces. They found a “decrease in baseline concentrations of [stress hormones] in right whales in association with decreased overall noise levels (6 dB) and significant reductions in noise at all frequencies between 50 and 150 Hz.” Stress hormones increased as ship noise returned to “normal” or baseline levels, and the authors note that “chronic stress, assessed by persistently elevated GCs, can lead to detrimental effects on health and reproduction across a variety of vertebrate taxa,” including whales.
This study was able to utilize an unintended set of control data to reveal useful evidence of how ship noise affects whales. For advocates, this research shows the major effect that even indirect human activity can have on other species.