Note: After this post was published, a fifth dead right whale was reported in the Gulf of St. Lawrence.

After two North Atlantic right whales were found dead in the Gulf of St. Lawrence (GSL) on June 4 (“Wolverine“) and June 20 (“Punctuation“), two additional dead right whales were reported in the region on June 25, 2019, bringing the total known mortalities to four. The third dead whale this month has been identified by the New England Aquarium’s Anderson Cabot Center as Catalog #1514, an adult male of unknown age named “Comet” for a long scar on his right side. He was first seen in April 1985 in Cape Cod Bay and was sighted nearly every year since and in all major right whale habitats. In 2017, he was photographed in the Gulf of St. Lawrence for the first time. He returned in 2018, and his most recent sightings this year were also in the gulf on June 5 and June 7 by the NOAA Northeast Fisheries Science Center aerial survey team.

Comet in the Bay of Fundy. Credit: Moira Brown, Anderson Cabot Center-New England Aquarium
Comet's namesake scar. Credit: Hansen Johnson, New England Aquarium/Canadian Whale Institute

Comet was an old favorite. Over the 33 years we followed him, he was often seen in surface active groups with other right whales, and paternity analyses confirm that he had fathered female Catalog #2042 in 1990. In 2013, #2042 made him a grandfather when she gave birth to her first calf. Based on the scars around his peduncle and fluke, we also know that the whale had been involved in three minor entanglements in his life.

Comet in a surface active group. Credit: Moira Brown, Anderson Cabot Center-New England Aquarium

The fourth dead whale has been identified as an 11-year-old female, Catalog #3815. She was just reaching sexual maturity and had not yet given birth to a calf.  She was born in 2008, but had a slightly unusual beginning. She and her mother, Catalog #3115 (“Harmony”), were not seen during the winter on the calving ground as most other mother-calf pairs are, but off New Jersey in May. The following January, when #3815 was a yearling, she was seen in waters off Georgia, still with her mother, but by the end of the month she was on her own.

#3815 in the Bay of Fundy. Credit: Dan Pendleton, Anderson Cabot Center-New England Aquarium
#3815 in the Bay of Fundy. Credit: Moira Brown, Anderson Cabot Center-New England Aquarium

She was sighted every year since, most often in Cape Cod Bay and, like Comet, was first photographed in the Gulf of St. Lawrence in 2017.  Also like him, she returned to the gulf in 2018, and her most recent sightings this year were also on June 5 and June 7 by the NOAA Northeast Fisheries Science Center aerial survey team. She had been entangled in fishing gear on four separate occasions. The first three were minor entanglements, but in 2017 her encounter was more serious and led to substantial scarring around her peduncle.

In 2018, she was seen often in the Gulf of St. Lawrence. Credit: Delphine Durette Morin, New England Aquarium/Canadian Whale Institute

With four carcasses discovered in a three-week span, the trauma from the events of 2017 is bubbling up in our minds. As right whales aggregate in the Gulf of St. Lawrence and continue to move throughout busy Northeast U.S. waters, we find ourselves holding our breath. It’s important to remember that the bulk of right whale mortalities have been attributed to anthropomorphic causes – namely, vessel strike and entanglement in fishing gear. A new paper by Dr. Sarah Sharp shows that between 2003 and 2018, “56 carcasses received external examinations, 44 of which were also necropsied. Cause of death was determined in 43 cases, of which 38 (88.4%) were due to anthropogenic trauma.” That’s almost 90%! When the results of a necropsy are inconclusive or undetermined, it doesn’t rule out that the death was caused by humans, it just means that a cause can’t be determined definitively, which is what science likes to do.