Fishing net lights save turtles and dolphins


This June 2019 video from the USA says about itsfelf:

Reducing Bycatch Helps Restore Sea Turtle Populations

Bycatch—when animals are accidentally caught while people are fishing for other species—is the biggest threat to sea turtles in the ocean. This project is helping reduce sea turtle bycatch and restoring their populations after the Deepwater Horizon [BP] disaster.

From the University of Exeter in England:

Lights on fishing nets save turtles and dolphins

December 5, 2019

Placing lights on fishing nets reduces the chances of sea turtles and dolphins being caught by accident, new research shows.

LED lights along the top of floating gillnets cut accidental “bycatch” of sea turtles by more than 70%, and that of small cetaceans (including dolphins and porpoises) by more than 66%.

The study, by the University of Exeter and Peruvian conservation organisation ProDelphinus, looked at small-scale vessels departing from three Peruvian ports between 2015 and 2018, and found the lights didn’t reduce the amount of fish caught from “target species” (ie what the fishers wanted to catch).

The findings support previous research which suggested LED lights reduce bycatch of seabirds in gillnets by about 85%. Gillnets, which can be either anchored or move with the ocean currents, are designed to entangle or snare fish by the gills, and are the largest component of small-scale fisheries in many countries.

“Gillnet fisheries often have high bycatch rates of threatened marine species such as sea turtles, whales, dolphins and seabirds,” said lead author Alessandra Bielli, who carried out analyses as part of her master’s research at the Centre for Ecology and Conservation at Exeter’s Penryn Campus in Cornwall.

“This could lead to declines in the populations of these non-target species — yet few solutions to reduce gillnet bycatch have been developed.

“Sensory cues — in this case LED lights — are one way we might alert such species to the presence of fishing gear in the water.”

The researchers placed lights every 10m along the float line of 864 gillnets, pairing each with an unlit net to compare the results.

“The dramatic reduction in bycatch of sea turtles and cetaceans in illuminated nets shows how this simple, relatively low-cost technique could help these species and allow fishers to fish more sustainably. Given the success we have had, we hope other fisheries with bycatch problems will also try illuminating their fishing nets,” said Exeter PhD graduate Dr Jeffrey Mangel, of Peruvian NGO ProDelphinus.

Most of the turtles caught in the study were green turtles (86%), though loggerhead and olive ridley turtles were also caught.

Among the small cetaceans captured, 47% were long-beaked common dolphins, 26% were dusky dolphins and 24% were Burmeister’s porpoises.

“This work has further shown the usefulness of lights on nets to save wildlife. We now need lights that are ever more robust and affordable,” said Professor Brendan Godley, of the University of Exeter.

Bottlenose dolphin mother adopts melon-headed whale calf


This 5 August 2019 video says about itself:

Dolphin Mom Adopts a Calf From a Different Species | Nat Geo Wild

A bottlenose dolphin mother off the coast of French Polynesia was spotted caring for a melon-headed whale.

How dolphins form friendships, new research


This March 2019 video is called How to Identify Indo-Pacific Bottlenose Dolphins.

From the University of Bristol in England:

Dolphins form friendships through shared interests just like us, study finds

June 12, 2019

When it comes to making friends, it appears dolphins are just like us and form close friendships with other dolphins that have a common interest. The findings, published in the Proceedings of the Royal Society B by an international team of researchers from the Universities of Bristol, Zurich and Western Australia, provide further insight into the social habits of these remarkable animals.

Shark Bay, a World Heritage area in Western Australia, is home to an iconic population of Indo-Pacific bottlenose dolphins, and the only place where dolphins have been observed using marine sponges as foraging tools. This learnt technique, passed down from generation to generation, helps certain dolphins, “spongers”, find food in deeper water channels. While the tool-using technique is well-studied in female dolphins, this study looked specifically at male dolphins.

Using behavioural, genetic and photographic data collected from 124 male dolphins during the winter months in Shark Bay over nine years [2007 to 2015], the team analysed a subset of 37 male dolphins, comprising 13 spongers and 24 non-spongers.

Male spongers spend more time associating with other male spongers than they do [with] non-spongers, these bonds being based on similar foraging techniques and not relatedness or other factors.

Dr Simon Allen, a co-author of the study and senior research associate at Bristol’s School of Biological Sciences, explains: “Foraging with a sponge is a time-consuming and largely solitary activity so it was long thought incompatible with the needs of male dolphins in Shark Bay — to invest time in forming close alliances with other males. This study suggests that, like their female counterparts and indeed like humans, male dolphins form social bonds based on shared interests.”

The study provides new insight into homophilous behaviour in the social network of tool-using dolphins.

Manuela Bizzozzero, lead author of the study at the University of Zurich, added: “Male dolphins in Shark Bay exhibit a fascinating social system of nested alliance formation. These strong bonds between males can last for decades and are critical to each male’s mating success. We were very excited to discover alliances of spongers, dolphins forming close friendships with others with similar traits.”

The study was funded by grants from the Swiss National Science Foundation, National Geographic Society, Australia’s Sea World Research and Rescue Foundation Inc (SWRRFI), W.V. Scott Foundation and the A.H. Schultz Stiftung.

Brazilian river dolphins communication, new study


This 2014 video says about itself:

A new species of river dolphin has been discovered by scientists working in Brazil. This is the fifth known species of its kind, and there are an estimated one thousand of the dolphins living in the Araguaia river basin.

Researchers from the Federal University of Amazonas ran genetic testing on some of the dolphins to be certain that a new species had been found. The last time a new species of river dolphin was discovered was back in 1918.

Doctor Tomas Hrbek, lead author of the study, is quoted as saying: “It is very similar to the other ones. It was something that was very unexpected, it is an area where people see them all the time, they are a large mammal, the thing is nobody really looked.” The Araguaia dolphins are smaller and reportedly have fewer teeth than the Amazon river dolphins, also called boto or pink dolphins, which are believed to be the most intelligent of the river dolphins.

From the University of Vermont in the USA:

Mysterious river dolphin helps crack the code of marine mammal communication

April 19, 2019

The Araguaian river dolphin of Brazil is something of a mystery. It was thought to be quite solitary, with little social structure that would require communication. But Laura May Collado, a biologist at the University of Vermont, and her colleagues have discovered that the dolphins can actually make hundreds of different sounds to communicate, a finding that could help uncover how communication evolved in marine mammals.

“We found that they do interact socially and are making more sounds than previously thought,” she says. “Their vocal repertoire is very diverse.”

The findings of May Collado are her colleagues were published in the journal PeerJ on April 18.

The Araguaian dolphins, also called botos, are a difficult animal to study. They are hard to find in the first place, and while the waters of the Araguaia and Tocatins rivers are clear, it is challenging to identify individuals because the dolphins are skittish and hard to approach.

Luckily, Gabriel Melo-Santos, a biologist from the University of St Andrews in Scotland and leader of the project, found a fish market in the Brazilian town of Mocajuba where the botos regularly visit to be fed by people shopping there. The clear water and regular dolphin visits provided a unique opportunity to get a close look at how the animals behave and interact, and to identify and keep track of various individuals.

The team used underwater cameras and microphones to record sounds and interactions between the dolphins at the market, and took some genetic samples. They identified 237 different types of sounds the dolphins make, but even with 20 hours of recordings the researchers don’t believe they captured the animals’ entire acoustic repertoire. The most common sounds were short, two-part calls that baby dolphins made when they were approaching their mothers.

“It’s exciting; marine dolphins like the bottlenose use signature whistles for contact, and here we have a different sound used by river dolphins for the same purpose,” says May Collado. The river dolphins also made longer calls and whistles, but these were much rarer, and the reasons for them are not yet clear. But there is some indication that whistles serve the opposite purpose than in bottlenose dolphins, with the botos using them to maintain distance rather than for group cohesion.

The acoustic characteristics of the calls are also interesting; they fall somewhere between the low-frequency calls used by baleen whales to communicate over long distances, and the high-frequency ones used by marine dolphins for short distances. May Collado speculates that the river environment may have shaped those characteristics.

“There are a lot of obstacles like flooded forests and vegetation in their habitat, so this signal could have evolved to avoid echoes from vegetation and improve the communication range of mothers and their calves,” she says.

May Collado and her colleagues next want to study whether the same diversity of communication is seen in other populations of Araguaian river dolphins that are less accustomed to humans, and compare them to their relatives elsewhere in South America. The Araguaian dolphins are closely related to two other species, the Bolivian river dolphin and Amazon river dolphin; the Araguaian dolphins were only described as a separate species in 2014, and that classification is still under debate. But there seems to be a large amount of variation in the repertoire of sounds each species makes.

The Amazon dolphins in Ecuador, studied by May Collado in 2005, are generally very quiet. “We need more information on these other species and more populations,” she says. “Why is one population chattier than others and how do these differences shape their social structure?”

May Collado says the work could help researchers gain clearer understanding of how communication evolved in marine mammals. Similar calls have been reported in pilot whales and killer whales, for example, and the similarities and differences between different species could help tease out which signals evolved first, and why.

The river dolphins are evolutionary relics, represented by just a few species around the world, and they diverged from other cetaceans much earlier than other dolphins. So these calls may have arisen first in river dolphins, then later evolved in marine dolphins into whistles and calls but in a different social context. Or was there a change in the function of the calls, with this kind of sound being used for group identity in killer whales, and individual identity in river dolphins? The calls may also have other functions in addition to identity, perhaps indicating group identity, or providing information on emotional state.

“We can’t say what the evolutionary story is yet until we get to know what sounds are produced by other river dolphins in the Amazon area, and how that relates to what we found,” she says. “We now have all these new questions to explore.”

Dolphins greet new born baby


This 28 July 2018 BBC video says about itself:

When a new baby dolphin is born, his family reunites around him to welcome him as one of them.

In a stunning new insight into the lives of wild dolphins, this film follows six remarkable months in the life of the ‘Beachies’: a family of six dolphins led by mother-to-be Puck, who live in the shark-infested waters of Western Australia‘s Shark Bay. Using the latest miniature cameras to eavesdrop on the Beachies’ underwater lives, this moving story follows Puck and the challenges she faces bringing up her newborn calf Samu. From learning to fish, to the ever-present threat of a shark attack, no day is ever the same. Including rarely seen footage of young dolphins and revelatory new behaviour, this is a heart-warming and emotional portrayal of one of the ocean’s most revered creatures.