Along the east coast of America, an unusual and sad phenomenon has been happening since 2016: Humpback whales have been washing up dead and stranded on the beaches of the east coast, causing concern among researchers as to the cause of these deaths.

From Maine through to Florida, coastal US states are reporting higher than average numbers of humpback whale mortality. In New York, 36 humpbacks have washed up dead in the last seven years, while 35 have been found in the same time frame in Massachusetts. In 2017 and 2020, 34 and 33 whales respectively were found dead across all 13 states. In total, 191 whales have washed up dead in the last seven years across the east coast.

In 2017, the event was declared an Unusual Mortality Event, defined as "a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response." by the National Oceanic and Atmospheric Administration (NOAA). 

Necropsies were performed on around 90 of the whales, finding that around 40 percent that were examined had been involved in either a ship strike or entanglements with fishing apparatus. While this is far from conclusive evidence as to the rise of humpback whale deaths, a team of researchers has been put together to review the data and continue monitoring these concerning mortality events. 

Other suggestions for the cause of this increase come from groups opposed to offshore wind farms. They have suggested that the planning and scanning stage of development for the wind farms, particularly off the coast of New Jersey, may have impacted the whales, although the Marine Mammal Commission responded by saying that “there is no evidence to link these strandings to offshore wind energy development” in a statement. 

Other explanations could be related to the increase in shipping usage, leading to strike events, particularly in the ports of New York and New Jersey, which had their highest cargo activity in history in 2022 according to the Port Authority.

Warming ocean temperatures and the impact of climate change could also be contributing to these whale events as humpback feed on krill, tiny ocean crustaceans, that are hugely impacted by warming conditions. Researchers are already studying the impact of the huge numbers of microplastics that humpbacks swallow with each mouthful.

NOAA has put together an interactive map showing the whereabouts of each stranded whale. Their website also provides guidance on who to contact should a member of the public come across a carcass.