Humpback whale found dead in Cumberland County river, Feb. 27, 2017
A humpback whale found dead in the Cohansey River in Cumberland County on Feb. 25, 2017.
(Photo provided by Ed Hymer)
Dead humpback whales continue to wash ashore on beaches along the Atlantic Coast, and no one is sure why.
The deaths of 41 humpback whales, dating back to January 1, 2016, from Maine to North Carolina has led the National Oceanic and Atmospheric Administration Marine Fisheries to declare an "unusual mortality event." The declaration, which now triggers an investigation into the cause of the whale deaths, was officially made on Thursday morning.
The declaration also comes just one day after a whale was found ashore near Chadwick Beach in Ocean County. (The type of that whale is as yet undetermined.)
This map from NOAA Fisheries shows where humpback whales have been found stranded on the Atlantic Coast since Jan. 1, 2016. Six of these strandings have occurred in New Jersey.
An "unusual mortality event" is defined by the Marine Mammal Protection Act as "a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response."
The average number of humpback whales found stranded annually from Maine to North Carolina is 14 per year. In 2016, 26 humpback whales were found in that range. So far in 2017, 15 have been found.
Yet the declaration may not solve what the mystery of what is killing these whales.
The last time a UME was declared for humpback whales off the Atlantic Coast was in 2006. Events were also declared in 2005 and 2003. In each of those three cases the cause of the UME was ultimately undetermined.
Since the UME program began in 1991, the investigations have determined causes for just 32 of 63 declared events.
During a press conference call on Thursday, NOAA officials were asked if environmental factors -- whether rising ocean temperatures or overfishing of the whale's prey -- could be the cause of the deaths, but said that no such conclusions could yet be drawn.
Mendy Garron, the stranding coordinator for NOAA Fisheries' Greater Atlantic Region, said in a conference call with members of the press that only 20 of the 41 humpbacks have been examined. Of these 20, ten showed signs of ship strikes either through blunt force trauma or propeller wounds.
Deborah Fauquier, a veterinary medical officer for NOAA's Office of Protected Resources, said that the injuries caused by the ship strikes were the cause of death in each of those ten cases.
NOAA added that no infectious disease linking the whales has been found, and that investigators at this point see no links between the dead whales.
Greg Silber, the coordinator of recovery activities for whales in the Office of Protected Resources, said the cause behind the surge of ship strikes is unknown.
"Generally speaking, especially with larger ships, most operators are unaware that they've hit a whale," Silver said.
The declaration of a UME does not lead to any immediate new regulations to protect the whales. NOAA does have the authority to issue ship traffic regulations in some cases. In 2008, NOAA imposed ship speed restrictions up and down the Atlantic Coast to protect endangered Right Whales.
Humpback whales were once listed as endangered, but the population off of the Atlantic Coast now averages more than 10,000 whales.
Members of the public who find a dead or stranded whale are asked to report it to NOAA by calling 1-866-755-6622.
Michael Sol Warren may be reached at mwarren@njadvancemedia.com. Follow him on Twitter @MSolDub. Find NJ.com on Facebook.