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A group of blue whales that frequent the South Taranaki Bight (STB) between the North and South islands of New Zealand appears to be part of a local population that is genetically distinct from other blue whales in the Pacific Ocean and Southern Ocean, a new study has found.
The whales show a high level of residency, researchers say, as hydrophones deployed in the region recorded blue whale calls on 99.7 percent of the days between January and December in 2016.
Study - Oregon - State - University - Marine
The study, led by Oregon State University's Marine Mammal Institute, is important because the South Taranaki Bight has several oil and gas extraction rigs and the New Zealand government recently issued its first permit for mining the seafloor there for iron sands.
Results of the study are being published this week in the journal Endangered Species Research.
Hydrophones - Years - STB - Blue - Whale
"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 Leigh Torres, a principal investigator with OSU's Marine Mammal Institute and co-author on the study. "When we conducted biopsies of individual whales, we also discovered that they are genetically distinct from other blue whale populations."
This journey of discovery began in 2011 when a colleague told Torres that observers aboard seismic survey vessels had spotted nine blue whales. Torres thought it was unusual, and began looking at whaling records, which suggested the South Taranaki Bight region historically was a minor "hotspot" for blue whale activity.
Patterns - Documentation - Upwelling - Supports - Aggregation
She then assessed oceanographic patterns and found documentation of local upwelling that "supports aggregation of a certain krill species that blue whales like to eat."
In 2013, Torres wrote a paper hypothesizing that blue whales may use this region because of a steady food supply. She said she received pushback from industry, resource managers and even other scientists...
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