Featured Image Credit: Douglas J Hoffman
Eva Gruber
A new study led by Sophie Pierszalowski of Oregon State University, utilizing 30-year old whale identification photos, has shown that humpback whale mothers teach their calves to return to the same summer feeding grounds in Glacier Bay and Icy Strait in Alaska. This culture of passing down site preference to offspring is crucial in that it allows the young whales to become familiar with certain places in the vast ocean where they can count on food and refuge. This is especially important in this time where humpback whale populations are still recovering from excessive whaling during the 19th and early 20thcenturies.
The Glacier Bay and Icy Strait humpback populations migrate each year from breeding and birthing waters around Hawaii, to feeding zones in Alaska. Dr. Pierszalowski set out to determine whether this recovering population is becoming more successful by birthing calves that stick to the same areas, or whether whales from other regions are simply moving into the relatively-vacant waters.
By going through data spanning the last couple of decades, as well as more modern and up-to-date genetic sequencing of skin samples, Pierszalowski was able to collect a sample size of 689 humpback whales. She was also able to create family lineages by combining the genetic samples with old photographs of different whales unique fin patterns. This was the most comprehensive study of a population of Pacific humpback whales.
Her study shows that 96% of the females sampled in the 1980s are still in the contemporary population – this shows that the population has grown from within itself, through children and grandchildren returning to the same waters as their mothers.
This information is vital in helping to protect and encourage Pacific humpback whale population, which fell to its lowest of 1,000 individuals in 1966 – the result of heavy international whaling efforts decimating the population. Currently, they are estimated at around 21,000 individuals and experience approximately a 5% growth every year.
With these results, we are better equipped to protect vital habitat for the Pacific humpback whales. This will involve creating Marine Protected Areas, as well as re-routing shipping traffic which poses a variety of hazards to all cetaceans. Some recent encouraging news is that NOAA has removed several populations of humpback whale from the endangered species list – a result of intense conservation efforts and the support of studies just like this one.