A study looking at the feeding behaviour of Australian fur seals in Bass Strait has found the animals benefit from the shipwrecks, pipelines and cables in their underwater world.
The researchers found these structures act like artificial reefs, attracting fish and other marine life. This makes them a happy hunting ground for hungry fur seals, which feed on a variety of bony fish, squid and octopus.
Revealed by the study's GPS tracking data and underwater "seal-cam" footage, the results showed the animals from the Kanowna Island colony off Wilsons Promontory favoured particular foraging routes.
"In one case we looked at the GPS track and it was a straight line, which made us think that the seal might be following fishing vessels," said John Arnould from Deakin University.
On closer inspection the researchers realised something else was at play: the animal's foraging path mirrored a pipeline. And it wasn't alone. Others were doing the same.
Underwater infrastructure in Bass Strait includes the high-voltage Basslink power pipeline, communications cables, wells and numerous shipwrecks.
Published in the journal PLOS ONE on Thursday, the findings showed this infrastructure benefited the fur seals because by forming an artificial reef, marine life became concentrated in what was otherwise a sandy seafloor with very little habitat variation.
Associate Professor Arnould said the Australian fur seals, which feed almost exclusively on the seafloor, appear to have cottoned-on.
"For some individuals it influenced where they were foraging and for some of the 36 studied, the artificial structures were heavily influencing where they were foraging," he said.
The research team, including scientists from the University of Tasmania and the University of California Santa Cruz, also looked at how far from the infrastructure the seals were feeding.
In some cases it was up to 100 metres but Associate Professor Arnould said this still indicated the artificial environment was having an impact on foraging behaviour.
"Structures can influence currents and therefore nutrient transport," he said. "So even if seals aren't always feeding on the pipeline, the pipeline is influencing where they forage."
On one case, black and white video footage of a seal foraging around an oil rig revealed a surprising number of fish concentrated in the area.
"The amount of fish around this structure was unbelievable," Associate Professor Arnould said.
Thirty-six Australian fur seals were fitted with a GPS tracker and dive recorder as part of the study. Two of the 36 had an underwater camera attached to their dorsal fur.
Heavily hunted for their coats in the 1800s, the Australian fur seal population dipped to as few as 20,000. Now protected, the seal population is recovering at about 3000 pups a year, or 2 per cent.
