Tasmania Parks and Wildlife Service (PWS) rangers on Macquarie Island are undertaking a Southern elephant seal census.
Counting started in early September and will continue until the end of November.
This year PWS rangers, with significant support of the Australian Antarctic Division (AAD) expedition team on the island, completed a whole island count of breeding female elephant seals in mid-October. The last time the whole island count was able to be undertaken was in 2014.
The census will help scientists estimate the size of the island’s elephant seal breeding population.
Tasmania Parks and Wildlife Service Deputy Secretary Jason Jacobi said the census of breeding female seals has been undertaken on Macquarie Island since the early 1980s, with the population estimated to be declining about 1.2 percent each year since 1989. Currently, the Macquarie Island population is approximately 10 percent of the global population which is recognised as a threatened species.
“The previous whole island estimate of 15,266 breeding females in 2014 indicated a decline of 34 percent, down from 23,211 over the 25 years since 1989. Everyone is now eagerly waiting to see what the estimate is this year based on the most recent whole island count,” Mr Jacobi said.
“We thank the Australian Antarctic Division and their expeditioners on the island for helping the rangers complete such a challenging elephant seal count”.
Research suggests that large-scale environmental change and variable Antarctic sea ice extent are contributing factors to the declines in Southern elephant seals observed in the Pacific Ocean populations.
The census figures will be also used by collaborating scientists from the Institute for Marine and Antarctic Studies (IMAS) and AAD seeking to understand the relationship between Southern Ocean variability and population trends of iconic Antarctic wildlife such as Southern elephant seals.
“During the breeding season, the Macquarie Island team is recording the number of breeding females returning to the island to give birth,” Mr Jacobi said.
“This starts with weekly counts on beaches around the northern end of the island on the Isthmus and increases to daily counts during the peak pupping period in mid-October when a single more extensive count occurs along larger sections of coastline when the maximum number of breeding females are present on the beaches. The weekly counts have now recommenced and will finish at the end of November.”
“Although some elephant seals are present on the island all year, the census period is the only time that all females are ashore to give birth and the team use this opportunity to estimate the number of breeding females.”