Sharks in French Polynesia


This video says about itself:

11 November 2017

Filming Sharks In Protected French Polynesian Waters – BBC Earth

The Blue Planet II team are filming in the protected waters of French Polynesia where shark species thrive. It’s an example of positive conservation measures in action and helps conserve the pristine reef habitat.

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Deep sea sharks video


This video says about itself:

Sharks Attack Submarine – Blue Planet II Behind The Scenes

4 November 2017

The Blue Planet II team dive to over 700 meters to see what happens to a whale carcass on the seabed. Whilst filming sharks as they feast, the sharks start to take a worrying interest in the submarine!

Alligators eat sharks, new research


This New Scientist video from the USA says about itself:

25 September 2017

A previously overlooked conflict between alligators and sharks has been going on for centuries at least, and it seems the alligators are winning. Read more here.

From Kansas State University in the USA:

Bite on this: Alligators actually eat sharks

October 16, 2017

Jaws, beware! Alligators may be coming for you. A new study documents American alligators on the Atlantic and Gulf coasts are eating small sharks and stingrays. This is the first scientific documentation of a widespread interaction between the two predators.

Jaws, beware! Alligators may be coming for you, according to a Kansas State University researcher.

While the sharks may not actually be as big as the fictional Jaws, James Nifong, postdoctoral researcher with the Kansas Cooperative Fish and Wildlife Research Unit at Kansas State University, and Russell Lowers, wildlife biologist with Integrated Mission Support Services at Kennedy Space Center, published a study in Southeastern Naturalist documenting that American alligators on the Atlantic and Gulf coasts are eating small sharks and stingrays. This is the first scientific documentation of a widespread interaction between the two predators.

“In the article, we documented alligators consuming four new species of sharks and one species of stingray,” Nifong said. “Before this, there have only been a few observations from an island off the Georgia coast, but the new findings document the occurrence of these interactions from the Atlantic coast of Georgia around the Florida peninsula to the Gulf Coast and Florida panhandle.”

Despite the freshwater and saltwater differences, Nifong said it is fairly common for sharks and rays to share the water with alligators. Many sharks and rays can swim into freshwater where opportunistic alligators can’t pass up a good meal. Although alligators don’t have salt glands like true crocodiles, they are resourceful as they travel between freshwater and marine habitats.

“Alligators seek out fresh water in high-salinity environments,” Nifong said. “When it rains really hard, they can actually sip fresh water off the surface of the salt water. That can prolong the time they can stay in a saltwater environment.”

An alligator’s diet typically consists of crustaceans, snails and fish, but because alligators are opportunistic predators, Nifong said sharks may end up on the menu.

“The findings bring into question how important sharks and rays are to the alligator diet as well as the fatality of some the juvenile sharks when we think about population management of endangered species,” Nifong said.

As part of Nifong’s dissertation research, he pumped the stomachs of more than 500 live and alert alligators to learn more about their diet. Researchers also equipped the alligators with GPS transmitters to watch their movements and found that alligators travel between freshwater sources and estuaries, which are a partially enclosed coastal water body where freshwater and salt water mix and house shark nurseries.

“The frequency of one predator eating the other is really about size dynamic,” Nifong said “If a small shark swims by an alligator and the alligator feels like it can take the shark down, it will, but we also reviewed some old stories about larger sharks eating smaller alligators.”

Nifong dug into history and found news reports from the late 1800s that described battles of large masses of sharks and alligators after flooding and high tides washed the predators together. One particular historical incident included in the journal article described how the sharks were attracted to blood from alligators feeding on fish. When the alligators were washed out to sea, the sharks attacked.

Nifong conducted the alligator diet research as part of larger research of freshwater river systems and food web dynamics. He currently is researching the drivers of native fish biodiversity in the Neosho River Basin for Martha Matter in the Kansas Cooperative Fish and Wildlife Research Unit, a part of the Division of Biology at Kansas State University.

See also here.

Hammerhead shark swimming, new research


This 2013 video is called Bonnethead sharks in slow motion.

From Florida Atlantic University in the USA:

Size doesn’t matter, at least for hammerheads and swimming performance

October 10, 2017

Different head shapes and different body sizes of hammerhead sharks should result in differences in their swimming performance right? Researchers have conducted the first study to examine the whole body shape and swimming kinematics of two closely related yet very different hammerhead sharks, with some unexpected results.

Sharks come in all shapes and sizes and perhaps the most unusual is the hammerhead shark, easily recognized by its oddly shaped head. Most research on hammerheads has focused specifically on their laterally expanded heads, or cephalofoil, and how they use it to see and smell as well as its effects on hydrodynamics and sensory efficiency. There are about nine known species of hammerhead sharks with dramatic differences in their body shape including the shape and size of their heads. While much is known about the variations in their electroreception, olfaction and vision, very little is known about whether or not their shape differences affect their swimming performance.

Researchers from Florida Atlantic University have conducted the first study to examine the whole body shape and swimming kinematics of two closely related yet very different hammerhead species: the Bonnethead and the Scalloped hammerhead, with some unexpected results.

Adult Bonnetheads are about 2 to 3 feet long and their head width makes up about 18 percent of their body length; adult Scalloped hammerheads are closer to 12 feet long and their head width makes up about 30 percent of their body length. Despite these differences, results of this new study, featured on the cover of the current issue of the Journal of Experimental Biology, find that in the end, size or shape really doesn’t matter, at least when it comes to swimming.

Using an interdisciplinary approach in the Biomechanics Laboratory in FAU’s Charles E. Schmidt College of Science under the direction of Marianne E. Porter, Ph.D., assistant professor of biological sciences and co-author of the study, the researchers set out to test their hypothesis. Different head shapes and different body sizes of hammerhead sharks should result in differences in their swimming performance.

Prior to starting the study, Porter, Sarah L. Hoffmann, lead author and a Ph.D. student of biological sciences, and Steven Matthew Warren, co-author and a senior in the Department of Mechanical and Ocean Engineering in FAU’s College of Engineering and Computer Science, reviewed CT scans of both species of hammerhead sharks. Because sharks are made up entirely of cartilage that is heavily mineralized, they were able see the marked differences in the two species of the sharks’ physiology from these scans.

To test their hypothesis, they focused on undulation, which is how a shark moves its body and tail from side-to-side to propel itself forward. The goal: to figure out if the movement of the body changes between these two species with very different head shapes.

Beginning in 2015, they viewed hours of video of Scalloped hammerheads and Bonnetheads swimming. They looked at tail beat frequency and tail beat amplitude. They analyzed video sequentially to select clips in which sharks completed at least three full tail beat cycles of straight, steady swimming. Warren analyzed and then condensed the videos into a minute-long segment to enable the research team to use the measurements to compare swimming mechanics between the two species. They were able to get all of the measurements they needed from that condensed one minute of video footage.

“One of the more unique aspects of our study is that we were able to observe these sharks swimming in large tanks moving around naturally,” said Porter. “Most studies place sharks in flumes, which are basically underwater treadmills that force them to move. We are interested in learning how these animals move in and of themselves for both conservation efforts and real world applications such as bioinspired engineering.”

Results of the study revealed that the Bonnetheads swing their bodies further in and out and therefore have a larger amplitude of undulation. On the other hand, Scalloped hammerheads bend faster and have a higher frequency of undulation.

“When we corrected for their body size, we discovered that they actually swam at the same speed to get to points A and B, but did so in different ways,” said Hoffmann. “Even though they are different, they get to the same destination at the same time; they’re just using different body mechanics.”

A key finding from their study is that in both species the head is moving at a different rate than the rest of the body. In fact, it is actually moving back and forth a lot faster than the rest of the body. Similar to sturgeons, a species of fish, the researchers discovered that these hammerheads have a double oscillating system. They speculate that it is because of an increased ability for sensory perception.

“There is no way that we could have anticipated the double oscillation system in this species,” said Hoffmann. “The head movement being different than the rest of the body movement is something that’s almost impossible to see with the naked eye.”

The researchers point out that with the double oscillation system, the shark’s head is moving at a much quicker rate than the rest of their body essentially to scan more of the substrate of their environment.

“Think of it like a metal detector as you move it back and forth,” said Hoffmann. “They’re going to be covering more territory for electroreception and olfaction and they need to be able to do that at a greater rate than the rest of their body.”

New Pacific marine parks


This video says about itself:

9 October 2017

Two countries have made a big new splash in ocean conservation. Niue, a tiny island in the South Pacific, has committed to protecting 49,000 square miles of ocean, including one of the world’s best habitats for reef sharks. Additionally, Chile will create two new reserves totaling 240,000 square miles. Both countries will restrict fishing in the new marine protected areas. All three reserves were scientifically supported by National Geographic Society’s Pristine Seas program.

Sharks, rays live longer than estimated before


THis 2014 video from the USA says about itself:

Stingrays and Manta rays come in many shapes and sizes… But one of the coolest rays in all the ocean has to be the giant Shark Ray.

In the front they are broad like a ray, but the back section they are all shark with dual dorsal fins. How cool is that! Also known as a bowmouth guitarfish, this large species can reach a length of 2.7 m (8.9 ft) and weigh up to 135 kg (298 lb).

WHERE TO SEE RAY SHARKS IN THE USA In one of the biggest resorts in town, there’s a major Aquarium with full grown Shark Rays in it. It’s called the “Shark Reef” and it’s main tank is filled with 1.3 million gallons of water. This Aquarium displays all kinds of sharks, rays, fish, reptiles, even a green sawtooth shark — but the real celebrities here are the Shark Rays….

Just step inside what they call the Shark Tunnel and within seconds you will have a very up close and personal encounter – guaranteed!

SHARK RAYS ARE A THREATENED SPECIES Shark Rays are not dangerous to humans. They like to eat crabs or lobsters and stuff like that but their numbers in the wild are dwindling due to overfishing. They are killed for the shark fin on top. It’s the main ingredient in Shark Fin Soup which is popular in certain parts of the world. Attempts to breed these amazing creatures in captivity so far has been a failure. Seven pups born at the Newport Aquarium in Kentucky all died within a few months of their birth.

From James Cook University in Australia:

Sharks and rays live a lot longer than we thought

September 29, 2017

A James Cook University researcher has found that sharks and rays live a lot longer than we thought — some twice as long as previously estimated.

Dr Alastair Harry looked at 53 different populations of sharks and rays that scientists had already intensely studied. He said in nearly a third of populations the studies had underestimated the animals’ ages.

“Questions arose over methods of ageing sharks after it was found that grey nurse sharks can live up to 40-years-old, double the length of time first thought, and the age of New Zealand porbeagle sharks had been underestimated by an average of 22 years,” he said.

Dr Harry said scientists usually measure shark age by counting growth rings in their vertebrae. These measurements are confirmed by tagging animals and injecting them with a fluorescent marker or by measuring carbon accumulated in the animals from atmospheric testing of nuclear weapons in the 1950s.

“Age underestimation appears to happen because the growth rings cease to form or become unreliable beyond a certain size or age. Across the cases I studied age was underestimated by an average of 18 years, and up to 34 years in one instance. From the amount of evidence we now have it looks like the problem is systemic rather than just a few isolated cases,” he said.

Dr Harry said accurate age estimation was important because it was used to manage fishery stocks.

He said the underestimation of longevity in orange roughy, a deep-sea fish, led to overly optimistic estimates of stock productivity, contributing to serious, long-term ecological and socio-economic impacts.

Dr Harry said sharks and rays are less commonly targeted by commercial fishers, but are still often caught as bycatch. That means the impacts of age underestimation may well take longer to become apparent.

“It could lead to inefficient prioritisation of research, monitoring and management measures. If it’s as widespread and common as it seems from this study, the impacts could also be substantial from a wider scientific perspective, affecting the many disciplines that also use baseline life history data,” he said.

Pakistani fishermen saved young whale shark


This video says about itself:

21 August 2017

WWF-Pakistan trained fisherman captain Ali Akbar along with his crew safely released a 7.5 feet juvenile whale shark caught in the gillnet, recently. The fishermen were carrying a fishing operation about 2 kilometres north of Churna Island, Balochistan. This is not the first time that a whale shark was rescued by fishermen, however, their pups seldom survive during the entanglement or die even in the rescue process. The baby whale shark was entangled in the net placed for catching tuna in the waters. When the crew members first tried to disentangle it [in the water] … the animal did not show any body movement, hence, it was heaved on board. As it was freed from the net, the baby started to move slightly. To the utter surprise and jubilation of the fishermen, the juvenile whale shark came to life and encircled the boat before disappearing in the deep sea.

Since the start of the Observer Programme of WWF-Pakistan in October 2012, a total of 61 cases of whale sharks have been documented. Before the programme, some fishermen used to kill whale sharks for liver oil if they get entangled in their fishing gear. Even though the population of whale sharks in Pakistani waters seems to be stable, however, it is extremely prone to frequent entanglement in fishing gear, habitat degradation and marine pollution.