‘Unusual mortality event’ declared for East Coast humpback whales

Submitted photo/MERR

DOVER — NOAA Fisheries officially announced an “unusual mortality event” for humpback whales from Maine to North Carolina on Thursday morning. The announcement comes on the heels of a dead whale — thought to be a humpback — found in the waters just off Port Mahon earlier this week.

The death toll leading to the declaration has risen to 41 whales from Jan. 1 2016, to date. The “event” will trigger a focused, expert investigation by National Oceanic and Atmospheric Administration into the cause of the unusually high death count.

According to NOAA data, the average annual humpback whale strandings reach eight per year — this historic data only goes as far back as 2000. In 2016, 26 mortalities were recorded and there have already been 15 more since the beginning of 2017. NOAA officials said that because the recently discovered Port Mahon whale has not yet been confirmed as a humpback, it does not yet appear in the 2017 total.

Suzanne Thurman, director of the Marine Education, Research & Rehabilitation Institute, who was headed to Port Mahon on Thursday to attempt another sample collection, is confident that it will eventually be the 42nd on the list.

“I am fairly certain that it’s a humpback,” she said. “There isn’t much left of it, but we need a sample to be sure, or if I can distinguish a flipper I may also be able to identify it that way.”

Of the 41 whale mortalities in the last 16 months, 10 of the 20 closely investigated bodies had evidence of boat interactions. Historically, only 1.4 whales die per year in the same geographical range due to boat strikes.

“The amount of boat strikes among the humpback whales is unusually high,” said Deborah Fauquier, NOAA’s veterinary medical officer.

Beyond this, NOAA is unsure of the cause behind the elevated body count. They have no evidence that widespread disease, infection or maritime “noise” contributed to the issue.

“Right now, the answer is unknown,” said Greg Silber, NOAA’s coordinator of recovery activities for large whales. “There probably hasn’t been a spike in vessel traffic in these areas, but the difficulty is that the animals move around. I think we’ll find that it’s linked to prey sources. Humpback whales follow prey and they may sometimes lead them close to shipping routes.”

The unusual mortality event declaration will help inform the investigation along the coast and provide resources to the various organizations collecting data in an attempt to understand the causes and make recommendations, said NOAA officials. Three prior investigations produced few results.

According to NOAA, unusual mortality events related to the East Coast humpback population — 10,400 to 10,754 whales at last check — were declared in 2003, 2005 and 2006. The cause for those events remained “undetermined” after the investigations concluded. However, the condition of this particular population isn’t as dire as it once was.

“This population was just recently de-listed and they’re no longer considered an endangered species along the Atlantic coast, but they are still protected under the Marine Mammal Protection Act,” said Ms. Fauquier.

NOAA offered the following advice to residents interested in helping with the investigation and observing best practices:

•Always report stranded, dead or beached whales to NOAA at (866) 755-6622 or MERR at (302) 228-5029.

•Observe safe viewing guidelines by offering whales a 100 foot berth at sea and avoid navigating through feeding areas

•Donate to or volunteer with NOAA or MERR by visiting noaa.gov/ or merrinstitute.org/

The whale discovered at Port Mahon still remains difficult to extract from its position near the shoreline. Several tide cycles since its discovery have moved it closer to land.

Due to the whale’s late stage of decomposition, identifying it accurately was tricky, said Ms. Thurman. The MERR Institute’s best guess is that the whale was a juvenile, originally about 30-feet long and close to 20 tons.

According to Ms. Thurman, the whale is now blocked on the bay side by rows of wooden pylons and the shore side by a bed of jagged rocks that would likely tear the carcass apart if dragged over it. Ms. Thurman said she’s considering a plan with DNREC currently that may involve lining the shore with tarps and dragging it over that.

Not including the Port Mahon whale, Delaware has seen three other dead whales wash ashore in the past 16 months. Two were determined to have died from human interaction — one from boat blunt force trauma and the other from being tangled in fishing gear. The third was not able to be examined.

Reach staff writer Ian Gronau at igronau@newszap.com

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