Dolphins

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.

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.

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.

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. 

Before they were closed down, these fisheries would cause the deaths of many harbor porpoises, as they ended up as bycatch in the fisheries' gillnets. And based on the numbers, it is apparent that such coastal set gillnets had taken a greater toll on the harbor porpoises than we realized.

This is the finding of a paper published in the Marine Mammal Science journal.

Whether or not you have watched (or agree with) the movies Free Willy or Blackfish, the predicament of captive cetaceans is one that can spark off a heated debate from both sides of the fence.

Nonetheless, such movies and increased awareness have led to public calls for attractions and venues that keep wild animals captive to release them.

Marine-animal attractions like SeaWorld are particularly under fire due to their animal shows featuring captive cetaceans trained to perform for public entertainment.

According to a new study, bottlenose dolphin colonized the Mediterranean after the last Ice Age, about 18,000 years ago. Leading marine biologists collaborated in the study, the most detailed ever conducted into the genetic structure of the Mediterranean’s bottlenose dolphin population to date.

A study of bottlenose dolphin deaths in the Gulf of Mexico conducted between 2010 and early 2013 has concluded the highest number of strandings and deaths occurred in areas most impacted by the 2010 BP Deepwater Horizon oil spill. In comparison, Gulf Coast areas of Texas and Florida, which experienced little to no oiling, saw few statewide increases in stranded dolphins during the same period.

There was something peculiar about dolphins that puzzled the prolific British zoologist Sir James Gray in 1936. He had observed the sea mammals swimming at a swift rate of more than 20 miles per hour, but his studies proposed that dolphins simply do not have the strength to swim so fast. The conundrum came to be known as “Gray’s Paradox.”