Of Whales And Ships: Impacts On The Great Whales Of Underwater Noise Pollution From Commercial Shipping And Proposals For Regulation Under International Law

Authors

Lora L. Nordtvedt Reeve

Document Type

Article

Abstract

On September 11, 2001 (“September 11”), a tragedy unfolded on the eastern seaboard of the United States that caused the sea to nearly empty of ships. This consequence of the terrible calamity in New York City opened an opportunity for a unique scientific study that may help to save the world’s whales. This rare experiment provides evidence that the undersea noise pollution generated by global commercial shipping slowly, chronically, and cumulatively cuts away at the lives of the great whales, including the critically endangered North Atlantic right whales, Eubalaena glacialis (“right whales”). The North Atlantic right whales are baleen whales that come each year to the productive waters of the Bay of Fundy, Canada to nurse their calves and forage for food. During the late summer of 2001, whale scientists from the New England Aquarium were studying the right whales in the Right Whale Conservation Area (“RWCA”) of the Bay of Fundy. The researchers were tracking hormonal changes in the whales, chiefly the hormones associated with stress. The scientists were watching for signs that the whales suffer from the effects of chronic stress, which could offer key information as to why the species has not recovered from its depletion by commercial whaling, despite strong legal and policy protections. The number of individuals in the North Atlantic right whale population is critically low, and the species remains endangered under both U.S. and international criteria. At the same time as the study above, other marine mammal scientists working on an unrelated project were also in the Bay of Fundy, monitoring the acoustic signals associated with the social behavior of the same right whales. This second group of researchers was looking for changes in the calls of the whales. Previous research had shown that high noise levels within the same low-frequency range that the great whales use to communicate causes the whales to raise the volume and frequency of their calls in order to be heard by others of their own species. The underlying scientific premise of both these studies is that underwater noise pollution significantly interferes with the whales’ natural communication and behavior, and therefore could be inhibiting the recovery of their species. The noise generated by the propulsion systems on commercial shipping vessels is of particular concern. The ships generate loud low-frequency background noise that may mask communication among the whales, as well as hindering the whales’ ability to navigate on their long migrations and to detect predators and prey. As the world stood still after the tragic events of September 11, most shipping activities in U.S. waters were halted, causing the underwater noise level to drop dramatically. The vessel management system for the Bay of Fundy recorded a substantial decrease in traffic in the shipping lanes that pass within sixteen kilometers of the RWCA. On August 25, 2001, there were five vessels in the RWCA lanes and on August 29, four vessels. Comparatively, only one ship passed through the Bay of Fundy on September 12 and two on September 13. The unprecedented decrease in ship traffic gave scientists the extraordinary opportunity to compare the whales’ stress hormone levels before and after September 11, and to correlate the findings with the intensity level of underwater noise from ships during the same time periods. The investigators’ conclusions were two-fold: 1) there was a “noticeable” decrease in the low-frequency background noise of the type that would mask communication among the right whales; and 2) this drop in the background noise level showed a statistically significant relationship to the reduction in the stress hormones in the whales. This study demonstrated that the reduction in underwater noise pollution from the shipping activities was directly related to a significant decrease in the stress levels of the whales. A large body of scientific literature shows that chronic stress, as measured by high levels of stress hormones, can lead to detrimental effects on health and reproduction across a variety of vertebrate groups, including mammals. If this is indeed the case with the North Atlantic right whales, reducing their stress hormone levels by reducing underwater noise pollution from shipping might lead to increased health and reproductive success, which could lead to the recovery of their species. Underwater sound from all sources, including shipping, is measured by the intensity of the source level in decibels. The standard source level reference for underwater sound is “re __dB 1 Pa at 1 m,” with one micropascal (1 Pa) as the unit of intensity, the number of decibels (dB) as the unit of the sound level, and one meter (1 m) as the distance from the source, where the blank is completed by adding the number of decibels. Underwater sound is also described by its frequency in hertz (Hz). Underwater noise pollution from large ships is among the most pervasive of anthropogenic sounds in the ocean that falls within the lowfrequency range of 5 to 500 Hz that may mask the sounds produced and heard by the great whales. “Over the past few decades, the shipping contribution to ambient noise has increased by as much as 12 [decibels] coincident with a significant increase in the number and size of vessels comprising the world’s commercial shipping fleet.” For comparison, a cargo vessel that is 173 meters long and sailing at 16 knots has a sound level of 192 dB, while a small boat outboard engine running at 20 knots has a sound level of 60 dB. Underwater noise pollution affects the mysticetes in many ways, some so subtle that they become apparent only when whale populations do not thrive, as in the case of the stress on the right whales. The adverse impacts are physical as demonstrated by the right whale study, and behavioral as documented extensively in the scientific literature. Most worrying of all are the hidden deaths of the whales that end their lives at sea due to the adverse impacts of long-term chronic stress or the whales that are killed by predators they could not detect due to masking. Those whales are never counted in the statistics of mysticete mortality from underwater noise pollution because no human eyes witness the causes of their deaths. This paper aims to contribute to the interdisciplinary field of marine policy, integrating marine mammal science and international ocean law to support policy to conserve the great whales. The paper explores underwater noise pollution from shipping as it affects the baleen whales and how the noise might be regulated to reduce the impacts. The first section discusses the use of sound by mysticetes, the impacts of underwater noise pollution from shipping, and the existing treaties and organizations with the authority for international regulation of marine pollution in general and underwater noise in particular. The second section examines the dual “shipping-conservation” mission of the International Maritime Organization (“IMO” or “Organization”) and whether the current global legal framework is effective for protecting the great whales. The third section offers some suggestions for improving international regulation of shipping noise with the objective of reducing its impact on mysticetes. The analysis presented here addresses one small but important part of the wider group of issues regarding the intersection – and often, the conflict – between conservation of marine resources and the economically significant activities that may have adverse environmental impacts. The paper concludes that the IMO, which regulates discharges of pollution from commercial vessels, has the competence under international treaty law to regulate underwater noise pollution from shipping and could issue guidelines for controlling the sources of shipping noise that impact the whales. While IMO regulation is one solution, this paper also briefly presents the possibility of a new global treaty to comprehensively address the impacts of underwater noise pollution from all sources as it impacts not only the great whales but also other marine species and ecosystems.

Recommended Citation

Lora L. Nordtvedt Reeve, Of Whales And Ships: Impacts On The Great Whales Of Underwater Noise Pollution From Commercial Shipping And Proposals For Regulation Under International Law, 18 Ocean & Coastal L.J. (2012).
Available at: https://digitalcommons.mainelaw.maine.edu/oclj/vol18/iss1/12