Migrating humpback whales show no detectable response to whale alarms off Sydney, Australia

Abstract

Migratory Group V (Stock E1) humpback whales Megaptera novaeangliae are at risk of entanglement with fishing gear as they migrate north and south along the east coast of Australia. This study investigated the effectiveness of 2 distinct tones for use as an alarm to acoustically alert whales to fishing gear presence and therefore reduce the chance of entanglement. We compared how whales responded in terms of changes of surface behaviour and changes in direction of travel in response to 2 acoustic tones and when there was no alarm. These 2 acoustic tones were a 5 kHz tone (5 s emission interval and 400 ms emission duration, similar to but higher frequency than the signal from a Future Oceans F3 TM 3 kHz Whale Pinger®) and a 2−2.1 kHz swept tone (8 s emission interval and 1.5 s emission duration). A total of 108 tracks (focal follows) were collected using a theodolite at Cape Solander, Sydney, Australia, during the whales' 2013 northern migration. Linear mixed effects models were used to determine the effect of the different acoustic tones on whale direction (heading), and behaviour (dive duration and speed). Whales showed no detectable response to either alarm. Whale direction and surfacing behaviour did not differ whether the alarm was 'on' or 'off'. Although the response may have been different if the alarms were attached to fishing gear, the lack of measurable response suggests that the types of tones used are not likely to be effective in alarms intended to reduce entanglement of northward migrating Australian humpback whales.

An Economical Custom-Built Drone for Assessing Whale Health

“…Each pod was considered independent as all whales were on their annual northern migration (Pirotta et al, 2016). Overall, 59 successful samples were collected from at least 48 different whales (11 whales were sampled but not identified via video due to occasional failure of the GoPro R camera e.g., low battery or maximum storage capacity reached).…”

A citizen science approach to long‐term monitoring of humpback whales (Megaptera novaeangliae) off Sydney, Australia

“…Citizen science, like the CSWMS, acts as “complementary tools to monitor cetacean biodiversity” (Lodi & Tardin, ). There have been a number of marine wildlife biodiversity studies conducted by scientists off Sydney (Gulesserian et al, ; Harcourt, Pirotta, Heller, Peddemors, & Slip, ; Pirotta et al, , ), but the intensive nature of the CSWMS provides a unique opportunity to document rarely seen marine species. For example, observations of southern right whales most likely from the Australian southeast stock, provided an opportunity for photo identification of individuals from this small and remnant population (Carroll et al, ).…”

First analysis of behavioural responses of humpback whales (Megaptera novaeangliae) to two acoustic alarms in a northern feeding ground off Iceland

“…The emitted sound from the whale pinger had an actual source level of 137 dB re 1µPa (rms) recorded at a distance of 1 m. The levels at 5, 10 and 20 m were 137 dB, 140 dB and 144 dB re 1µPa (rms) respectively using spherical spreading as transmission loss. Based on previous modelling of the pinger sound, humpback whales are expected to detect the sound at a distance of at least 500m from the source [24, 26]. The seal scarer had an actual source level of 189-198 dB re 1µPa (rms) measured at a distance of 20, 30 and 40 m using spherical spreading (of 20 Log R) as transmission loss.…”

“…19, 20]. Whale pinger and low-frequency acoustic alarm sound experiments have been conducted on baleen whales, including North-Atlantic right whales ( Eubalaena glacialis ) [21], minke whales ( Balaenoptera acutorostrata ) [22], grey whales ( Eschrichtius robustus ) [23], and humpback whales [24, 25, 26, 27, 22]. Results from these experiments were also highly variable.…”

“…Humpback whales were also less likely to collide with cod-traps fitted with alarms in Canada [27] and were found to respond to “tone stimuli” within their hearing range in Australia [29]. By contrast, grey whales did not appear to respond to acoustic deterrent sounds though results were inconclusive [23] and the majority of recent research conducted on humpback whales in Australia has concluded there is no clear response to the modern whale pinger alarms, some of which are now sold commercially [24, 25, 26]. Despite this, anecdotal reports do claim that some industries have had lower incidence of humpback whale entanglement with the use of the commercial whale pingers [30, 31].…”