Whales

Brains of stranded marine mammals have shown the hallmarks of Alzheimer’s disease, according to new research

Toothed whales show signs of Alzheimer's disease

A study of 22 toothed whales which died in strandings along the Scottish coast shows that some of them exhibited hallmarks of Alzheimer’s disease, and this might have—at least in part—caused the stranding incident.

The dolphin species involved in the study were five species: Risso’s dolphins, long-finned pilot whales, white-beaked dolphins, harbour porpoises and bottlenose dolphins.

Acoustic signals show blue whales go to oceanic upwellings to feed

From March to July, phytoplankton blooms emerge along Calfornia’s Central Coast, as seasonal winds push the top layer of the waters out to sea, thereby allowing the cooler, nutrient-rich waters to rise to the surface.

Many marine animals are drawn to such oceanic upwellings, which consequently turn into their feeding grounds. For instance, krill gather to feed on the abundant phytoplankton, whilst blue whales converge to feed on the krill.

Once the upwelling ceases, these marine creatures move elsewhere.

Sperm whales form clans with diverse cultures

After studying more than 23,000 sperm whale vocalisations recorded from 1978 to 2017 in the Pacific Ocean, researchers have concluded that sperm whales use distinctive vocalisations to identify themselves with specific whale clans.

Called “identity codas,” these vocalisations comprise sequences of clicking sounds that distinguish different social groups. They are different from non-identity vocalisations used across all the different whale clans.

Orcas and humpbacks brawl

Whale watchers were making their way toward the U.S.-Canadian border in the Strait of Juan de Fuca when the captain spotted the group of whales. At first, whale watchers observed what they thought was a pod of roughly 15 Bigg’s orcas swimming and "being unusually active at the surface." Before long, it became apparent that two humpback whales were in their midst.

A tagged fin whale
A tagged fin whale

New satellite tag tracks long-term whale behaviour

Keeping an eye on whale behaviour is not easy, considering the fact that they travel vast distances and spend the majority of their time beneath the ocean surface.

To counter this, researchers at Oregon State University {OSU) have developed a new satellite tag that can track the whales' movements, even during dives.

Known as RDW, this new technology incorporates pressure and accelerometer sensors, thus giving the researchers the opportunity to monitor the whales’ movements underwater for several months.

Fin whale feeding aggregation.
Fin whale feeding aggregation of ~70 fin whales encountered during RV Polarstern expedition in 2018

Groups of fin whales spotted in Antarctic, suggesting recovery after whaling

Fin whales (Balaenoptera physalus quoyi) of the Southern Hemisphere were brought to near extinction by 20th-century industrial whaling. For decades, they had all but disappeared from previously highly frequented feeding grounds in Antarctic waters. Researchers estimate that by the time whaling was banned in the 1970s over 700,000 fin whales had been killed.  

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Unidentified beaked whales sighted in Nemuro strait. Note the short beak, dark body colour, and sparse linear scars (photo taken by Hal Sato on 21 May 2009).
Unidentified beaked whales sighted in Nemuro strait. Note the short beak, dark body colour, and sparse linear scars (photo taken by Hal Sato on 21 May 2009).

First live sighting of elusive Sato's beaked whale

For decades, Japanese whalers have known of the existence of a whale species that resembles the Baird’s beaked whale, but is smaller in size. It was only in 2019 that DNA samples taken from deceased whales were able to confirm their existence.

The new species was named Sato’s beaked whales, after researcher Hal Sato, who sent photos of deceased stranded individuals to Tadasu Yamada, curator emeritus at Japan’s National Museum of Nature and Science, in the early 2000s.

The vaquita, the smallest and most endangered cetacean in the world, is endemic to the northern part of the Gulf of California. This photo was taken under permit (Oficio No. DR/488/08) from the Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT).

Critically endangered vaquita could survive if gillnet-poaching ban enforced

The vaquita is the world’s smallest marine mammal, measuring between four to five feet in length. A comprehensive survey conducted in 1997 counted 570 vaquitas, but today, 25 years on, a mere ten surviving vaquitas have been counted in the Sea of Cortez, the only place that the vaquita can be found.

Breaching humpback whale
Breaching humpback whale (pixabay license)

Southern Hemisphere whale-call research highlights need for MPA network

The “whup” and “grumble” sounds recorded by hydrophones moored in the Vema Seamount in the Atlantic Ocean, 1,000km northwest of Cape Town in South Africa, suggest this location could be an important stop on the whales’ migration route to polar feeding grounds.

Humpback whale straining krill
Humpback whale straining krill

Whales' baleen plates disclose their dietary habits

Scientists have discovered that the baleen plates of toothless whales can reveal how these mammals adapt to environmental changes over time. By examining the baleen plates, which held a chemical record of their feeding patterns, scientists could find out how changes in the whales’ feeding habits corresponded with the changing climate cycles.

After a study involving humpback and right whales in the Pacific and Indian Ocean, they published their findings in the Frontiers in Marine Science journal.