SEATTLE — A satellite-linked tag fired into an endangered southern resident orca by U.S. biologists led to a fungal infection that contributed to the whale’s death, scientists said Wednesday.
U.S. fisheries officials on Wednesday released the findings into the death of a 20-year-old whale named L95. Fisheries and Oceans Canada researchers found the male floating dead on March 30 off Nootka Island on the west coast of the Island, with fragments of a dart tag in its dorsal fin. The death prompted the agency in April to temporarily halt its dart-tagging program.
Five weeks before the orca was found dead, National Oceanic and Atmospheric Administration researchers in the U.S. used a dart to fire the small satellite-linked transmitter into the animal.
The transmitters track where the whales go in the winter and how they find food. They are the size of a 9-volt battery and attach to the fin with two titanium darts just over five centimetres long. They are designed to detach over time and leave nothing behind in the whale.
An examination of the dead animal concluded that a fungal infection entered the orca’s bloodstream, causing the whale’s death, according to a report released Wednesday. A panel of five outside experts reviewed and agreed with the findings.
Some advocates have criticized the tagging, saying it injures the orcas and there are less invasive ways to monitor the small population of whales.
Richard Merrick, NOAA Fisheries’ chief scientist, told reporters during a conference call that some extenuating factors may have predisposed the whale to a fungal infection, including human error from not sterilizing the dart tag after it had fallen into the water during a failed first attempt.
The tag also hit the whale on its lower dorsal fin near significant blood vessels, broken parts of the tag also remained in the animal and the whale’s health may have been compromised at the time it was tagged in February, Merrick said.
“NOAA and the biologists who work with these whales are deeply dismayed that one of their tags may have had something to do with the death of this whale,” he said.
“There’s always a risk involved when you’re conducting research on wild animals. But it’s our job and our obligation to reduce that risks, and that’s what we’ll continue to do.”
The satellite-tagging program will be suspended until the agency has completed its own review of the program, Merrick said.
NOAA’s Northwest Fisheries Science Center in Seattle will also create an independent panel to review the need for further satellite tagging of Puget Sound resident orcas and consider alternative methods of gathering information on the whales. Recommendations are expected next year.
And NOAA’s Office of Protected Resources will consider additional conditions to reduce injury or infection for all future tagging efforts on whales, dolphins and other cetaceans.
The whale was a member of L-Pod, one of three southern resident pods that live in the area from the Salish Sea as far south as California.
About 80 whales live in these three groups, which are considered endangered by Canadian and U.S. authorities. Their numbers have fluctuated in recent decades as they have faced threats from pollution, lack of prey and disturbance from boats.
NOAA is considering whether to expand habitat protections for the orcas to include offshore areas from Washington to Northern California, and Merrick said the tagging program has been crucial to understanding the animal’s habitat.
The tags have been used numerous times on whales and other marine mammals, as well as eight Puget Sound orcas.
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