Relative abundance and behavior of marine mammals exposed to transmissions from the Heard Island Feasibility Test

Abstract

The Heard Island Feasibility Test source transmitted a hum at 209-220 dB re: 1 microPa at 175-m depth, centered on 57 Hz with a maximum bandwidth of 30 Hz for 1 h of every 3. Experienced marine mammal observers conducted line-transect surveys and monitored marine mammal behavior visually and acoustically in a 70 x 70 km square centered on the transmission site. Thirty-nine groups of cetaceans and 19 of pinnipeds were sighted from both vessels before the start of transmissions. Thirty-nine groups of cetaceans and 23 of pinnipeds were sighted during transmissions. Blue (Balaenoptera musculus), fin (B. physalus), and sperm (Physeter macrocephalus) whales were sighted during the base line period; blue, sperm, and possibly sei (B. borealis) whales were sighted during the transmission period. More schools of hourglass dolphins (Lagenorhynchus cruciger) were sighted during transmissions, but fewer groups of pilot whales (Globicephala melas), southern bottlenose whales (Hyperoodon planifrons), and minke whales (B. acutorostrata). The density of all cetaceans was 0.0157 groups/km2 before the transmissions and 0.0166 groups/km2 during. Antarctic fur seals (Arctocephalus gazella) and southern elephant seals (Mirounga leonina) were seen, but not in sufficient numbers to estimate abundance. One blue whale tracked before, during and after a transmission changed respiration and reorientation rates, but did not avoid the source detectably. Sperm whales and pilot whales were heard in 23% of 1181 min of baseline acoustic surveys; but in none of 1939 min during the transmission period. Both species were heard within 48 h after the end of the test.

No evidence for recovery in the population of sperm whale bulls off Western Australia, 30 years post-whaling

“…Environmental noise in the form of seismic explorations is known to be audible to sperm whales (Madsen et al 2006); however, there are conflicting reports on the extent to which this noise may trigger behavioural responses (Mate et al 1994, but see Madsen et al 2002) or interfere with the complex vocalisations that sperm whales employ for hunting and socialization (Bowles et al 1994, but see Madsen et al 2002). Although there has been long-term seismic exploration in relation to a petroleum deposit between Albany and Esperance along Australia's southern coast, the infrequency of this activity and the distance from the study site (>1000 km from Albany) probably preclude this from being a major source of concern, as it may be for example in the Gulf of Mexico (Mate et al 1994).…”

Widespread spatial and temporal extent of anthropogenic noise across the northeastern Gulf of Mexico shelf ecosystem

“…Marine mammals, including sperm and humpback whales, have exhibited avoidance reactions to active airguns (Malme et al 1984, Mate et al 1994, Richardson et al 1995, McCauley et al 2000, and changes in vocal behavior and foraging efforts (Bowles et al 1994, Jochens et al 2008. Blue and fin whales have also been documented to drastically alter their vocal behavior and exhibit avoidance in response to seismic surveys (Di Iorio & Clark 2010).…”

Point Mugu Sea Range Marine Mammal Technical Report

“…They may cease calling when exposed to weak noise pulses from extremely distant seismic exploration {greater than 186 miles or 300 kilometers away; Bowles et al 1994). Sperm whales may move away from a seismic vessel at somewhat closer range (Mate et al 1994), or behave unusually (S. M, Dawson, University of Otago, persona!…”