Antarctic killer whales head north to regenerate skin tissue in warm waters
Posted November 11, 2011
New research published by NOAA scientists suggests a type of Antarctic killer whale migrates north not necessarily to breed or forage — but to regenerate skin tissue in a warmer environment.
The study, published in October in the science journal Biology Letters, tagged 12 Type B killer whales near the Antarctic Peninsula. Researchers tracked five by satellite that revealed consistent movement to subtropical waters, including one animal that traveled more than 8,000 kilometers to visit the warm waters off southern Brazil before returning immediately to Antarctica just 42 days later.
This was the first long-distance migration ever reported for killer whales, according to a press release from NOAA.
“The whales are traveling so quickly, and in such a consistent track, that it is unlikely they are foraging for food or giving birth,” said John Durban , lead author from NOAA’s Southwest Fisheries Science Center (SWFSC) in La Jolla, Calif. “We believe these movements are likely undertaken to help the whales regenerate skin tissue in a warmer environment with less heat loss.”
As evidence, the researchers point to the yellowish coating on Antarctic killer whales caused by a thick accumulation of diatoms or algae on the outer skin of the animals. The coloring is noticeably absent when they return from warmer waters, indicating the upper epidermis of the skin has been shed.
The whales tended to slow in the warmest waters although there was no obvious interruption in swim speed or direction to indicate calving or prolonged feeding, according to the authors.
“They went to the edge of the tropics at high speed, turned around and came straight back to Antarctica, at the onset of winter,” said Robert Pitman , co-author of the study, also with SWFSC. “The standard feeding or breeding migration does not seem to apply here.”
Last year, Pitman was a co-author on a study that suggested there are at least three different types of killer whales in Antarctica. Part of his research was supported by the National Science Foundation . [See previous article — Killer news: Scientists suggest several new species of orcas, including in the Antarctic.]