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Endangered Species Research

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ESR 25:35-42 (2014)  -  DOI:

A whale alarm fails to deter migrating humpback whales: an empirical test

Robert Harcourt1,*, Vanessa Pirotta1, Gillian Heller2, Victor Peddemors3, David Slip1,4

1Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia
2Department of Statistics, Macquarie University, Sydney, NSW 2109, Australia
3Fisheries NSW, Sydney Institute of Marine Science, Sydney, NSW 2088, Australia
4Taronga Conservation Society Australia, Sydney, NSW 2088, Australia
*Corresponding author:

ABSTRACT: Cetacean entanglements in fishing gear cost governments, fishermen and stakeholders millions of dollars a year, and often result in serious injury or death of the entangled animals. Entanglements have been implicated in preventing the recovery of some large whale populations. Acoustic deterrents on fishing nets are widely used to reduce incidental captures of dolphins and porpoises, but there is little evidence as to whether they effectively deter large whales. We tested whether a low-frequency whale alarm (3 kHz Whale Pinger®, 135 ± 5 db, 5 s emission interval and 400 ms emission duration) deterred Southern Hemisphere humpback whales Megaptera novaeangliae from approaching a potential source of entanglement. Northerly migrating humpback whale pods were tracked by an observer blind to alarm status (on/off) as they passed an alarm moored in the centre of the peak migration path. Of 137 pods tracked, 82 (60%) passed within the assumed detectable range (500 m) of the alarm, 51/78 (65%) when it was on and 31/59 (52%) when it was off (p = 0.18). There was no discernible response to the alarm. Whale pods did not differ in directionality, course heading or dive duration when within detectable range of the alarm, whether it was on or off, and a number of pods passed directly over the alarm while it was operational. This suggests that single alarms as currently configured and attached to a trap or pot line are unlikely to effectively deter humpback whales from approaching potential hazards, at least during their northerly migration phase.

KEY WORDS: Fisheries entanglement · Mortality · Bycatch · Acoustic deterrents · Megaptera novaeangliae

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Cite this article as: Harcourt R, Pirotta V, Heller G, Peddemors V, Slip D (2014) A whale alarm fails to deter migrating humpback whales: an empirical test. Endang Species Res 25:35-42.

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