As anyone who has travelled to Seal Rocks can attest, it’s the smell that hits you first. “It’s a strong smell, a mix of wet dog and rotting carcass,” says seal researcher Jessalyn Taylor. Then comes the noise. “Other fur seals have a high-pitched trill, but the Australian fur seals here sound like a foghorn. The juveniles sound like screaming goats.”
Jess knows the sound and smell well. For her research the 29-year-old PhD student has stayed on Seal Rocks for about five days several times over the past two years, to weigh, measure and gather body condition data on 100 seal pups, at four to six weeks and five to six months of age.
“It’s noisy,” she says, “they call all day and night. I need to invest in good earplugs. I get about five hours sleep a night. But you get used to the smells and the sounds and it’s amazing just to see them in their natural habitat.”
The Seal Rocks sleep-over is just one part of a multi-pronged research project investigating the impact of human noise on seal populations, with surveys since 2007 showing pup numbers on the rock, off the Nobbies, have decreased 30 per cent over a decade.
Another critical element of the research is investigating the impact of boat noise on seals. Over two years four hydrophones – or acoustic recorders – have been anchored in two locations around Seal Rocks, onto the sea floor, to a depth of up to nine metres: the first for a month in April 2022, then again for a month this past summer.
The hydrophones record boat noise, monitoring how many boats, their frequency, and the level of noise. We joined Jess on board a boat off Seal Rocks, to retrieve the hydrophones, for a final noise analysis. The boat is run by professional diver Johno Rudge, who works alongside his team – diver Ben Rhodes and skipper Tom Bowman – motoring off Anderson Road boat ramp in perfect conditions.
Today Western Port and the mouth of the bay is tranquil. Once at Seal Rocks Ben dons wetsuit, hooks up to a tube – surface supplied breathing, commonly known as a hookah – and dives in among the seals.
“I could snorkel,” he says before diving into the 20C water, “but using the tube is safer.” While Ben is underwater, Johno steers the boat above. As a diver working along the Victorian coast, Johno carries out work as varied as underwater construction, salvage and scientific research, including in past years surveying for the Wonthaggi desalination plant.
He visits Phillip Island about six times a year, mostly for abalone stock assessment. “The diving off Phillip Island is completely different to other areas. The geology has a lot of formations,” Johno says. “Seal Rocks is another nice place because the seals are really playful and curious. They pull on our hoses, steal our pencils and bite on our flippers.”
After about 15 minutes Ben re-emerges, carrying two hydrophones about 50cm long, encased in Perspex sealed tubing. “The seals were coming right up to my face,” Ben says. “They were blowing bubbles at me, territorial, but pretty chilled and curious.”
Jess, though, is baffled: one of the Perspex casings around a hydrophone has leaked, permanently damaging the equipment and probably the sound recordings along with it. She points to a missing wingnut, probably lost thanks to the massive swells.
According to Phillip Island Nature Parks, noise pollution caused by humans – such as boat and jet ski noise – has become a widespread issue in the world’s oceans, affecting many marine species.
Little is known about its impact on Australian fur seals, but there is some evidence that loud boat noise can disrupt vital behaviour and vocal communication between seals, which can impact health and survival, especially if animals are already stressed or in a compromised state of health. Seal pups are born over summer, when recreational vessel visitation is high and pups are most vulnerable because they are too young to swim and live independently.
“We don’t know how – or if – the noise is impacting them,” Jess explains. “Boat noise is one thing out of a number of things that could be adding to this impact. We don’t yet know and that is why we’re doing the research.”
While there are blanket regulations for boats near wildlife, each seal colony is different and at Seal Rocks it is 20 metres for a permitted tour vessel, 60 metres for all other boats and 260 metres for jet skis – to the boundary of the colony. “Regulations for approach distances at Seal Rocks have been developed despite little understanding of the consequences of vessel noise and visitation on the seals.”
While Jess says stress from noise and vessel visitation at Seal Rocks is just one possible threat to the fur seals and their pups, if significant impacts are detected Nature Parks will work with Victorian environment department to revise regulations. “This could include a revision of approach distances to Seal Rocks, or just greater compliance with the current regulations to ensure people understand that it is harmful to the seals if they approach within 60 metres of Seal Rocks.”
The seal research project started in March 2021 and will run for at least three years.
Jess, who lives in Melbourne and grew up in Colac, completed an undergraduate science degree at Melbourne University and is now studying at Sydney University, successfully applying to oversee the seal project. She is not only supervised by Nature Parks’ Dr Rebecca McIntosh, but also Associate Professor Rachael Gray, from the Sydney School of Veterinary Science, and Dr Isabelle Charrier from the Université Paris-Saclay.
“I learnt acoustic analysis for a month at that university in Paris in order to analyse the data from the hydrophones,” Jess says. The research – all performed under permit – is not only studying the impact of a boats on the fur seals.
Aside from the hydrophones and Seal Rocks sleep over, the third element of the research – sees Jess play noises to seal pups on Seal Rocks and monitor their reactions, four times during the study period. “You can infer their reactions and see whether they’re in states of stress or relaxation. I monitor them pre, post and during the recordings.”
Jess also monitors boats from the Nobbies’ boardwalks, with the data compared between winter when there is less visitation and the peak summer period. She adds Penguin Foundation donors contributed $20,000 towards the research along with several key sponsors.
Despite one of the hydrophones being damaged during the summer, Jess clearly relishes being around the seals. “If you had asked me five years ago what I’d be doing, I would never have imagined it would be this. Seal Rocks is my happy place. I feel lucky to be doing this research.”
By Sarah Hudson
Photos: Sarah Hudson