migratory routes

Welcome to Whale Week! This week we’ll be bringing you photos and information about the whales that call national marine sanctuaries home. 

This is Salt, one of the most famous humpback whales in the world today. She was first spotted in Massachusetts Bay in the 1970s, and has been seen in Stellwagen Bank National Marine Sanctuary just about every year since then. She was one of the first northern humpback whales to be recognized at breeding grounds at Silver Bank off the coast of the Dominican Republic, providing proof of the humpback whale migratory route in the North Atlantic. 

Salt has had 14 calves and many grandchildren – and in 2014, she became a great-grandmother! She appears to be a leader among her peers, often diving and resurfacing before others when in a group of feeding whales. 

(Photo: Laura Howes)

ANTARCTICA’S BLUE WHALE ARE MADE UP OF THREE POPULATIONS

Antarctica blue whales (Balaenoptera musculus intermedia) a critically endangered subspecies and the largest extant animal, are made up of three populations, according to a recent study of Australian researches based in a new DNA analysis, the results are published in Scientific Reports.

Researchers suspect that the three populations go their separate ways when they head north to breed – presumably heading into the three major Southern Hemisphere ocean basins: the South Pacific, South Atlantic and Indian Oceans. Individuals from the three populations occur together throughout the Antarctic, although possibly in different proportions in different areas. This is probably because the blue whales need to rove long distances around Antarctica to find the massive amounts of krill that make up their sole food source.

Scientists urge that future research should invest in locating the breeding grounds and migratory routes of Antarctic blue whales through satellite telemetry to confirm their population structure and allow population-level conservation.  

Antarctic blue whales reduced in abundance from 239,000 before hunting commenced in the 1904/05 austral summer season to a low of 360 when they were last hunted in the 1972/73 season. The most recent abundance estimate was 2,280 from surveys conducted between the 1992/93 and 2003/04 austral summer. This is only about 1% of pre-exploitation abundance. The subspecies is classified as Critically Endangered in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.