Commercial fishing can be a risky business, but not when you have the right members on your team! In some locations, fishermen are getting help from self-trained Bottlenose Dolphins! This is a winning outcome for the dolphins as well as for the fishermen that are reaping such rewards. What is really interesting in this study in Brazil is that the dolphins were never formally trained for such an outcome.

What has occurred is that the dolphins are successful with getting the fish into a central location. Then they send out signals to the fishermen that inform them where they should drop their nets to catch the fish. It is very evident the social and cooperation skills of these dolphins are extremely well developed.

Additional research on these dolphins also shows they are extremely social and cooperative within the group. This is based on information that has been published in the Royal Society Biology Letters if you are interested in finding out more. It is believed that these factors help to explain why some of the dolphins in the wild do help humans and other don’t take part in it.

The behaviors are well synchronized and fishermen have been able to rely on those signals. They often include tail or head slaps in the water in given locations. The fishermen are able to quickly put their nets in the right place. This allows them to get the fish instead of guessing where to put the nets and hoping for the best. Such information has been observed and documented by Fabio Daura-Jorge of the Federal University of Santa Catarina.

Along with several colleagues, he has been able to see the outcome of such experiences. So what is in it for the dolphins? They get to dine on the fish that find their way out of the nets. They are patient and wait for that moment to arrive. Such observations were noted by Daura-Jorge and his team through boating surveys that took place over the course of a 2 year period.

They used photos to identify the dolphins. This allowed them to classify the groups as cooperative or non-cooperative based on their interactions or lack of interactions with the fishermen. The use of computer modeling allowed for the social relationships among the dolphins to be successfully identified.

What was found is that those dolphins that were cooperative spent far more time with each other, even when they weren’t participating in activities that helped the fishermen. It is believed that there are many factors at work here that determine if a relationship will occur naturally between humans and dolphins. They include genetics, social learning, and ecology. 

It is believed that information transferred from one generation of the dolphins to the next is very important here. The older dolphins teach the younger ones to be able to successfully help the fishermen. There have been numerous documentations about such behaviors within groups of dolphins in various areas. One that is widely discussed is the process of sponging by the dolphins in Shark Bay, Australia. If you aren’t familiar with sponging, it is the process of these Bottlenose Dolphins tearing pieces of sponges and covering their snout with them while they forage for food. This protects them from damages to that part of the body. 

There are plenty of unique behaviors identified within dolphin groups, and their intelligence level is believed to be a big part of them. According to Lori Marino from Emory University, the size of the dolphin’s brain should be used to help measure their intelligence. She and many others believe the dolphin ranks #2 – right being humans.

Source: http://news.discovery.com/animals/helpful-dolphins-120502.html

The Boto dolphin (Inia geoffrensis), inhabits the Amazon basin and part of the Orinoco river basin, so it has a wide variety of species available to eat, although it prefers fish since it feeds on more than 43 types, including the feared piranhas. Complementary this dolphin also eats crabs and turtles.

It consumes about 2.5% of its body weight daily.

Bottlenose dolphins diet consists mainly of small fish with occasional squid, crabs, shrimp, and other smaller animals.

Their teeth are not used to chew the food. When they find a shoal of fish, dolphins work as a team to keep the fish close together and maximize the intake. They also search for fish alone. Sometimes dolphins employ “fish whacking” where a fish is stunned (and sometimes thrown out of the water) with the fluke to catch and eat the fish easier especially when dealing with large specimens.

In some Mediterranean areas sometimes there is a conflict between common Bottlenose Dolphins and small-scale commercial fisheries looking for the same prey. Common Bottlenose Dolphins are probably attracted to fishing nets because they make easier for dolphins eat from a concentrated food source.

There are several species of herring, being the most common the Atlantic Herring.

This species is registered as the most available fish in the ocean by the Guinness book of records, which makes them at the same time, the most hunted species by dolphins.

The Atlantic Herring dwells on both sides of the Atlantic.

Spinner dolphins eat several kinds of fish, jellyfish, squid, krill and some types of snails that lack the shell.

Although spinner dolphins gather in small groups for hunting, they remain coordinated with sounds and the usual whistles.

They usually submerge from 250 to 1,000 meters deep to hunt their prey. Eels, shrimp, and lanternfish (myctophids) also complement their diet.

Pacific white-sided dolphins inhabit the temperate waters of the Pacific Ocean from Baja California, Mexico to Alaska. Therefore it eats some of the common species of fish in these regions. Among them, herring, sardines, salmon, anchovies, squid and some other small fishes.

This dolphin consumes about 9 kg of food every day and can be organized into groups to chase and ambush fish to eat more efficiently.

The food that dolphins eat is different for each species.
While some dolphins eat fishes like herring, cod or mackerel, some others eat squids or other cephalopods.

Even more, large dolphins like killer whales, eat marine mammals like seals or sea lions and sometimes even turtles.

Usually, the amount of fish that they eat depends on the kind of fish that they hunt. While mackerels or herrings have a lot of fat, squids do not have much fat, therefore, to get the energy required for their activities, dolphins have to eat more of the latter.

On average, a dolphin with a weight of 200 – 250 Kg will eat between 10 Kg to 25 Kg of fish every day.

Usually, to hunt fish, some species of dolphins use a method called herding which is a cooperative hunting performed by a pod where some of them surround a school of fish to compress them as much as possible, while some others take turns to eat through the compacted school of fish.

Another method is corralling where dolphins take fish to shallow waters where they cannot escape.

Some species catch larger fish by hitting them with their tails to stun them and in the case of killer whales, they

Therefore the question about what do dolphins eat has to be answered for every species in particular.

In this video, you can watch a pod of dolphins working together to feed themselves and using the technique called herding to catch the fish as they surround the school of fish, and then some of them take turns to eat.

In the video, you can learn more about What do dolphins eat.