Sea lions and seals get hearing tests for noise study

Scientists in Australia trained sea lions and fur seals at Sydney's Taronga Zoo to take hearing tests as part of research into how human-made noise may affect marine mammals.

Keepers trained two sea lions and two fur seals to listen for sounds and press a paddle when they heard a tone. The animals were rewarded with fish for correct responses.

Christine Erbe, a Curtin University professor and the study's lead researcher, said the tests provide a baseline for understanding how noise from ships, boats, aircraft and coastal construction might affect seals and sea lions.

The peer-reviewed study found the animals were most sensitive to sounds around 3.2 kilohertz. Erbe said the research is especially important for the endangered Australian sea lion, which has an estimated population of about 12,000 and relies on hearing for communication, finding food, navigation and detecting threats.

Benjamin Pitcher, a behavioural biologist at Taronga Conservation Society Australia, said the findings could help inform environmental impact assessments and noise management as shipping, coastal development and offshore industries expand. He said the next step is to understand how noise affects the animals underwater and when it begins to interfere with their behaviour or hearing.