Evidence that ship noise increases stress in right whales

Abstract

Baleen whales (Mysticeti ) communicate using low-frequency acoustic signals. These long-wavelength sounds can be detected over hundreds of kilometres, potentially allowing contact over large distances. Low-frequency noise from large ships (20-200 Hz) overlaps acoustic signals used by baleen whales, and increased levels of underwater noise have been documented in areas with high shipping traffic. Reported responses of whales to increased noise include: habitat displacement, behavioural changes and alterations in the intensity, frequency and intervals of calls. However, it has been unclear whether exposure to noise results in physiological responses that may lead to significant consequences for individuals or populations. Here, we show that reduced ship traffic in the Bay of Fundy, Canada, following the events of 11 September 2001, resulted in a 6 dB decrease in underwater noise with a significant reduction below 150 Hz. This noise reduction was associated with decreased baseline levels of stress-related faecal hormone metabolites (glucocorticoids) in North Atlantic right whales (Eubalaena glacialis). This is the first evidence that exposure to low-frequency ship noise may be associated with chronic stress in whales, and has implications for all baleen whales in heavy ship traffic areas, and for recovery of this endangered right whale population.

Changes in bottlenose dolphin whistle parameters related to vessel presence, surface behaviour and group composition

“…This study suggests that the acoustic parameters of whistle vocalizations vary naturally according to behavioural context and group composition, but are also influenced by tour boat presence and engine noise. The vocalization changes we observed in the presence of one or more tour boats could have a long-term, negative influence on the bottlenose dolphin population in Walvis Bay if they reduce the communication range of whistles (Jensen et al, 2009), result in increased energy expenditure (Holt, Noren, Dunkin, & Williams, 2015;Williams et al, 2006) or elevate stress levels (Rolland et al, 2012;Romano et al, 2004). Such effects would be compounded if combined with other behavioural responses to tour boat presence that increase energy expenditure, for example increased socializing or travelling (Indurkhya, 2012).…”

“…Although excessive noise can cause hearing damage, and even strandings in cetaceans (Weilgart, 2007), the more relevant impacts of boat noise generated through marine tourism activities are likely to be the masking of calls (Jensen et al, 2009) or biological cues (Clark et al, 2009), behavioural changes (Williams et al, 2006) or displacement (Rako et al, 2013), and stress (Rolland et al, 2012). Animals can adjust their acoustic signalling behaviour to respond to increases in noise in several different ways, which are not necessarily mutually exclusive.…”

Blue whale earplug reveals lifetime contaminant exposure and hormone profiles

“…2A). Cortisol is a biomarker of stress in mammals with concentrations directly associated with responses to a combination of environmental, physical, chemical, and social factors (21)(22)(23)(24). During this response, glucocorticoid steroid hormones are released into the blood stream with the amount reflecting the severity of the stressor (25).…”

Multi-year longitudinal profiles of cortisol and corticosterone recovered from baleen of North Atlantic right whales (Eubalaena glacialis)

“…However, some alternative sample types can be collected from whales, including feces, blubber biopsy dart samples, and respiratory vapor (e.g., Hogg et al, 2005Hogg et al, , 2009Hunt et al, 2006Hunt et al, , 2013Hunt et al, , 2014aKellar et al, 2006;Rolland et al, 2005;Vu et al, 2015). For example, fecal GCs of North Atlantic right whales (Eubalaena glacialis, NARW) show significant increases corresponding with energetically-demanding states such as pregnancy and lactation, as well as with anthropogenic stressors of chronic ocean noise and entanglement Hunt et al, 2006;Rolland et al 2005Rolland et al , 2012. Unfortunately, longitudinal glucocorticoid profiles from individual whales have been extremely difficult to obtain, the best exemplar being one study of GC content of annual cerumen (earwax) layers from a single blue whale (Trumble et al, 2013).…”