North Atlantic right-whale researchers have discovered that four calves that were previously thought to be dead had actually survived.
A new study led by the New England Aquarium provides insight into the survival of North Atlantic sand whale calves, growth rates and the life history of this critically endangered species.
The researchers analyzed all North Atlantic sand whale calves born between 1988 and 2018 and categorized the animals based on genetic samples and photo identification. The researchers focused on 13 case studies of right whales that required genetics to track their life history data.
They were able to determine the age of 12 whales, matched 11 with their birth mothers, and determined that the four calves had actually survived.
“The results of this study have changed what we know about the time of separation between a mother and a calf, as well as the physical development of the calves, all crucial information for a critically endangered species numbering less than 350 individuals,” said lead author Philip Hamilton. senior researcher at the New England Aquarium’s Anderson Cabot Center for Ocean Life.
The research showed that it is not uncommon for mothers to be seen without their calves in the feeding areas for short periods already in April – and some calves socialize with different mothers for short periods.
The data reveal that mothers and calves are seen separately at the feeding grounds off New England and Canada in 10% to 40% of all spring and summer observations. Prior to this study, calves were assumed to be dead if their mothers were always alone in the feeding grounds during the calf’s year of birth. Using genetics and photo identification, four calves believed to be dead were discovered alive.
In a case study, the female whale “War” was seen alone at the birthplace off Massachusetts in May 2004, questioning whether her calf was alive. A biopsy sample from “Seadragon” three years later determined that the calf had actually survived.
The study underscores the importance of using both photographs and genetics from young marine mammals, as well as degraded carcasses, to accurately capture individual life history data.
“Genetic sampling of animals early in their lives before they are spread or separated from their mothers provides an important means of individual identification at a time when photo identification is not as reliable,” Hamilton said. “All of this information is essential to help save this species from the brink of extinction.”