A new population of genetically distinct blue whales was discovered in the South Taranaki Bight (STB) between the North and South Islands of New Zealand.
Researchers have been monitoring the area as its a region with a great deal of human activity from gas and oil extraction operations. Recently, the New Zealand government issued a permit for seafloor mining in the area.
Blue whales are the largest mammals on Earth and are currently endangered.
A new study conducted by researchers from the Oregon State University’s Marine Mammal Institute shows that the area is home to a considerable population of blue whales and that these are genetically different from other populations.
The results were published in the journal Endangered Species Research.
Previously researchers discovered an unusual site of nine blue whales on a seismic survey expedition in the STB in 2011.
Leigh Torres, a principal investigator from the Marine Mammal Institute, followed up on this discovery and reviewed whaling records that stated the area was a “minor hotspot” for blue whale activity.
The STB area is attractive to the whales because of the populations of certain krill species that the whales like to eat, according to Torres.
Torres continued her work and led a ten-day research expedition in 2014 despite pushback from resource managers, scientists, and industry leaders. During the expedition, the researchers found 50 blue whales in the area and wondered whether they were part of a migratory population or a genetically distinct population.
The researchers returned to the area in 2016 and 2017 in order to establish how many whales were present in the region, the whales’ distribution patterns, and if they were genetically distinct.
Biopsy darts were used to determine the whales’ genetics and the researchers positioned underwater microphones, or hydrophones, throughout the area to pick up and record whale calls.
The whales were recorded in the STB region nearly 100 percent of the 2016 year.
“We had five hydrophones deployed for two years in the STB and we never heard any Australian blue whale calls – just the local New Zealand population,” said Torres, a co-author of the recent study. “When we conducted biopsies of individual whales, we also discovered that they are genetically distinct from other blue whale populations.”
All in all the researchers identified 151 New Zealand blue whales between 2004 and 2017 and after analyzing the genetic data, it was confirmed that the whales were not part of another migratory population.
Because of the high amount of human activity in the STB, the study and the researchers’ work is of vital importance in ensuring the protection and conservation of the New Zealand blue whales.
The team is working with resource managers in New Zealand and will soon discuss their findings with government leaders and industry representatives to find ways to mitigate the threat of population loss from human activity.
Image Credit: Todd Chandler