Dolphins

Includes orcas

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.

New subspecies of bottlenose dolphin identified

A new bottlenose dolphin subspecies has been identified, and it is found only in the eastern tropical Pacific Ocean, according to a study published in the Journal of Mammalian Evolution.

Called the Eastern Tropical Pacific bottlenose dolphin (Tursiops truncatus nuuanu), it is smaller than other common bottlenose dolphins, and is likely to prefer the deep offshore waters between southern Baja California and the Galapagos Islands. 

The so-called “dive response” is not merely a reflex in dolphins, but an active response.

Why aren’t dolphins getting bent?

Marine mammals are not above the physical principles and processes that lead to bubble formation in tissues following decompression. Scientists once thought that diving marine mammals were immune from decompression sickness, but beached whales have been found to have gas bubbles in their tissues—a sign of the bends. In any case, how some marine mammals and turtles can repeatedly dive as deep and as long as they do has perplexed scientists for a very long time.

The vaquita is currently listed as Critically Endangered by the IUCN Red List
The vaquita is currently listed as Critically Endangered by the IUCN Red List

Mexico enhances vaquita protection

The Mexican government has announced the successful conclusion of a project involving the placement of 193 cement blocks on the sea floor in strategic locations in the vaquita’s habitat.

Called the Concrete Block Planting project, the objective was to discourage the setting of gillnets within the Zero Tolerance Area, where the remaining vaquita population is localised. Large steel hooks protrude from the top of the blocks, trapping any gillnets they come into contact with.

Dolphin BFFs?
Dolphin BFFs?

Male dolphins form lifelong bonds

Researchers have discovered that male bottleneck dolphins form long-term social groups to help one another find mates and fight off competitors.

It was the first time such behaviour was observed in the animal world.

Their conclusions were based on data collected of 202 Indo-Pacific bottlenose dolphins between 2001 and 2006 in Shark Bay, Australia, using visual and auditory data. In the lab, the researchers then focused on studying the interactions of 121 of individuals for the next decade.

Harbour porpoise in Denmark.
Harbour porpoise in Denmark.

How toothed whales use echolocation to hunt

Can hunting by echolocation be as fast as hunting by sight?

As visual animals, we may find this a peculiar question—not so if one applies it to animals that hunt using echolocation, like bats, dolphins and whales. These animals emit clicking sounds and use the reflected echoes to determine the location of objects and other animals.

Can animals that hunt using echolocation lock onto their prey and track their movements, and how fast can they react? These were questions that an international team of researchers sought to answer.

Screengrab from New Scientist's video showing the mud ring made by the dolphins in the Caribbean.
Screengrab from New Scientist's video showing the mud ring made by the dolphins in the Caribbean.

Dolphins in Caribbean trap fish with mud nets

In 2019, a pair of bottlenose dolphins in the Caribbean—a mother and her calf—was filmed in the Chetumal-Corozal Bay in northern Belize using mud rings to catch fish.

This method of catching fish was first observed and documented in several parts of Florida by Stefanie Gazda, a researcher from University of Florida in 2005.

Common dolphin (NOAA NMFS/Wikimedia Commons/Public Domain)
Common dolphin (NOAA NMFS/Wikimedia Commons/Public Domain)

Share your views on Scotland's first cetacean conservation strategy

Focusing on nine of the most commonly found dolphin, whale and porpoise species in UK waters, the strategy has been developed by the Scottish Government, in collaboration with the UK Government, the Welsh Government and the Northern Ireland Executive.

Its objective is to ensure the effective management to achieve and maintain the current favourable status of the nine species. It highlights certain pressures where further research or extra management measures may help to improve the conservation of marine mammals.

Mmo iwdg / Wikimedia Commons / CC BY-SA 3.0
Long-finned pilot whale cow with her calf, off the coast of Ireland. Photo by Mmo iwdg / Wikimedia Commons / CC BY-SA 3.0

Buoy in Celtic Sea tracks oceanic noise

Equipped with an autonomous hydrophone, the buoy's function is to conduct for the first time real-time acoustic monitoring of the water's cetaceans to assess how oceanic noise pollution affects them. 

Deployed as part of the Smart Whale Sounds project, it will also track the distribution and behaviour of whale species in real-time and be used to train machine learning models to identify different species' calls.