Whale strandings spike on northwest US coast
It’s a bad year for grey whales, reports Lynda V. Mapes ,of The Seattle Times.
STRUCK by a ship, entangled in crab pots, stillborn, emaciated: It’s been a tough three months for whales.
Since April 3, whales — mostly greys and humpbacks — have been entangled and/or stranded on the beach in Oregon and Washington in numbers not seen in nearly two decades, with 16 cases of large whale strandings so far, the National Oceanic and Atmospheric Administration’s (NOAA) Office of Protected Resources says.
That is the most strandings in Washington since 19992000, when there was a big spike in dead whales all along the West Coast. This season, as then, scientists have counted many emaciated calves among the dead in Washington.
Among the lost so far this season: a 9.5m yearling grey whale that was hit by a ship and washed ashore late last month, dying hours later. A dead orca calf also washed up in Ocean Shores a few days later.
Jessie Huggins, of the Cascade Research Collective in Olympia, did a full postmortem on the orca. She said genetic analysis would determine within a few weeks whether the baby was a member of the southernresident orca pods, critically endangered and with no successful pregnancies for the past three years.
The infant calf appeared to have died from a trauma during birth, Huggins said.
As for the grey whale, it probably was healthy before it was struck by a ship, probably three to four weeks ago, judging by the amount of healing that had occurred at the wound, said Huggins, who did a postmortem on that animal also. Four vertebrae had been shattered. But after it was struck, the whale was unable to swim normally to feed and was badly emaciated when it washed ashore.
‘‘I’m glad it was quick at that point, for the animal’s sake,’’ she said.
‘‘This is definitely a high mortality year for greys,’’ said John Calambokidis, of the Cascadia Research Collective.
But it is nothing like the losses in 19992000, when the population appeared to reach carrying capacity and 651 greys died from Mexico to Alaska.
The cause of the grey whales’ troubles this year was not yet understood, he said.
‘‘The picture is still emerging.’’
David Weller, who runs the greywhale monitoring programme for NOAA out of its Southwest Fisheries Science Centre in La Jolla, California, said longterm data collected by the agency showed the big picture for greys was actually good.
‘‘What is going on this year is not overly alarming to me,’’ Weller said.
‘‘It is of interest; we are keeping an eye on it. But based on what we have seen grey whales go through in the past, the ups and downs and changes over time, they do just carry on and the population continues to grow.’’
The agency’s longterm data over the past 25 years has also pointed to a correlation between greywhale calf survival and the extent of sea ice in the Arctic. ‘‘These guys give us a way to peer into the Arctic,’’ Weller said. ‘‘They are a sentinel species.’’
If the pregnant females cannot get at their food source in the Arctic, it shows in the decline in birth rates the following year.
A second issue plaguing greys and humpbacks this year is entanglement, which has been trending upward, said Kristin Wilkinson, regional stranding coordinator for Washington and Oregon for NOAA Fisheries Protected Resources Division West Coast Region in Seattle.
The average for Washington and Oregon was about three to four whales entangled each year and this year there had been seven already, Wilkinson said.
The increase held true along the West Coast, said Justin Viezbicke, NOAA’s stranding coordinator for California.
Between 2000 and 2013, the average was about 10 confirmed entanglements reported per year. In 2017, 31 whales were confirmed entangled off the coasts of California, Oregon and Washington. In 2016, there were 48 confirmed cases and in 2015 there were 50, the highest annual totals for the West Coast Region since NOAA Fisheries started keeping records in 1982.
The reasons could be whales following a changing food web closer to shore, as they chase bait fish. It also could be increased fishing pressure with more gear in the water, or even just more reporting.
Humans have always been the biggest threat to whales, hunted for their oil, captured for aquariums, even shot for target practice. The protection provided for whales and all other marine mammals under the Marine Mammal Protection Act has allowed for the recovery of most species in the eastern North Pacific and Salish Sea.
Grey whales have rebounded so robustly they were taken off the Endangered Species Act list in 1994.
The major exception is southernresident killer whales, which remain critically endangered. The annual census reported to NOAA last month by the Centre for Whale Research tallies just 75 southern residents, the lowest number in decades.
❛These guys give us a way to peer into the Arctic. They are a sentinel species❜
— the NOAA’s David Weller