Shark Newz

Two mako sharks. Photo courtesy of NOAA Fisheries Service. Flickr/Creative Commons.

LONG BEACH (USA)- This summer the secret underwater lives of sharks will be revealed by a new underwater robot.

Biologist Chris Lowe from California State University Long Beach and engineer Chris Clark from Harvey Mudd College in Claremont, California have been developing a shark-tracking robot for the past three years to learn more about the fishes’ habits.

Although sharks receive more media attention than any other fish, marine scientists still don’t know much about how they live.

Researchers often rely on anecdotal reports from commercial fishermen to understand the range and behaviour of fish. But the shark industry is relatively small, so anecdotal information is scarce.

Now that will change. Read more at Wired. Or see the video below:

Grey reef shark. Photo courtesy of Flickr Creative Commons/PacificKlaus

PERTH (AUSTRALIA)- The diving behaviour of sharks could be influenced by the moon, water temperature and time of day, new research by the University of Western Australia’s Oceans Institute and the Australian Institute of Marine Science has revealed.

Grey reef sharks
Scientists of the two institutes studied about 40 grey reef sharks - commonly found on coral reefs in northern Australia and in the Indo-Pacific – and found they stayed in deep water during a full moon and moved to shallow water with the new moon.

Diving behavior
The sharks were tagged near Palau, east of the Philippines, and followed for two years using acoustic telemetry. The group of mostly adult females were recorded diving to an average depth of 35m in winter and 60m in spring.

Deeper water
In winter, when deeper waters were colder, the sharks remained closer to the surface where the water was warmer, but moved around to a range of depths in summer.

Researchers suggest that because sharks are cold blooded, they may prefer warmer water to conserve their energy.

To their knowledge, the researchers say, it  is the first time such patterns have been observed in detail for reef sharks.

Source: The Australian News

MIAMI (USA)- Great whites are lone predators but when their is a dead whale floating around they are much more social than thought to be. Experts studied social behaviour of white sharks around a dead whale in the cold waters of South Africa.

The study is titled, White sharks (Carcharodon carcharias) scavenging on whales and its potential role in further shaping the ecology of an apex predator.

In it, Captain Chris Fallows from Apex Expeditions collaborated with University of Miami (UM) scientists Dr. Neil Hammerschlag and Austin Gallagher, to explore the behaviors of Great white sharks scavenging on dead whales in South Africa.

The team documented as many as 40 different sharks scavenging on a carcass over the course of a single day, revealing unique social interactions among sharks. See the video below.

The study summarized observations based on four scavenging events opportunistically observed over a 10 year period. In each multi-day observation, the team recorded daily evidence of social, aggregative and feeding behaviors observed in the waters off South Africa. They suggest that although the occurrence of coming upon a whale carcass may be sporadic, the shark populations are likely prepared to scavenge on them, and may even rely on their scavenging activities to supplement their regular feeding activities.

“Although rarely seen, we suspect that as white sharks mature, scavenging on whales becomes more prevalent and significant to these species than previously thought,” said Hammerschlag, who is director of the R.J. Dunlap Marine Conservation Program at UM.

The team found that sharks showed a clear preference for scavenging on the blubber, probably because these high calorie meals can sustain the sharks for longer periods of time. Interestingly, though, the study also found that sharks showed an initial preference for feeding on the whale’s fluke before moving on to feed on the rest of the carcass. The team also found that while scavenging on whales, they ceased hunting and feeding on seals, one of their primary natural prey.

“While scavenging on the whale, the sharks clearly showed a size-based pecking order,” said Fallows. “The biggest sharks came right in, targeting areas of highest blubber content, while smaller sharks fed on areas with less blubber or kept their distance from the whale, mostly scavenging on pieces of blubber that drifted away from the carcass.”

The paper reveals how the social and size structure of sharks at the carcass appeared to be influenced by environmental patterns. “The cues, such as the oils, emanating from this pulse of food are likely attracting much larger sharks over 4.5 meters from long distances to scavenge,” said Gallagher. “These data provide some credence to the hypothesis that large white sharks may be swimming known ocean corridors looking for dead, dying, or vulnerable whales.”

“By attracting many large white sharks together to scavenge, we suspect that the appearance of a whale carcass can play a role in shaping the behaviors, movements, and the ecosystem impacts of white sharks” said Hammerschlag. “These patterns may shed some light into the ecology of this often studied – yet still highly enigmatic – marine predator.”

White sharks scavenging on whales from R.J. Dunlap Marine Conservation on Vimeo.

Dead sharks at a market. Photo: Flickr Creative Commons/StringsOfASoul.

GILBERT ISLANDS (KIRIBATI)- Overfishing is not just a sign of modern times. Hundreds of years ago species vanished by overfishing. That is the important conclusion of a study of ancient Pacific weaponry. In Kiribati at least two shark species.

A collection of vicious weapons made of shark teeth reveals that two species of sharks vanished from the reefs of Kiribati before scientists even noticed the species were there.

Until about 130 years ago, residents of the Gilbert Islands, which make up much of the Republic of Kiribati in the Pacific Ocean, used teeth from dusky sharks (Carcharhinus obscrus) and spotfin sharks (Carcharhinus sorrah) to make swords, spears, daggers and other fearsome weapons. Today, spotfin sharks can be found near Australia and Indonesia, and dusky sharks can be spotted near Fiji — but neither plies the waters around Kiribati.

Read more at NBC News.

Two headed bull shark. Photo courtesy of Michigan University

EAST LANSING (USA) – Scientists at Michigan State University have confirmed the discovery of the world’s first-ever two-headed bull shark. It has two heads, two hearts and two stomachs, and is joined at the back to form a single tail.

The shark was found in the uterus of an adult bull shark in the Gulf of Mexico in April of 2011.

The scientists call it “certainly one of those interesting and rarely detected phenomena”, but cannot yet draw any conclusions about what caused this.

The shark had little, if any, chance to survive in the wild, according to the scientists.

The research was published in the Journal of Fish Biology.

Amy, a 16.3 foot female great white shark is guided onto the lift. Photo courtesy of Ocearch.

JACKSONVILLE (USA)- The first great white in the waters off the southern state of Florida was caught and tagged by Ocearch researchers. She weighs 2,000lbs, is 14ft 6in long and her Florida guardians have called her Lydia.

The great white shark with the unassuming name was hauled on deck for 15 minutes so she could be fitted with electronic tags. Lydia is the latest addition to an elite club of great whites in the Atlantic and Indian oceans now being tracked from space. They can be followed at Shark Tracker.

Lydia is one of 38 sharks tagged in the Atlantic and Indian oceans, most off southern Africa. Their names belie their fearsome reputation; the list includes Edna, Albert, Philip, Maddox and Mary Lee, a 16ft great white weighing 3,500lbs tagged and released last September off Cape Cod, Massachusetts.

See the video:

Read more at Scotsman.com.

HALIFAX (CANADA)- One endangered species endangers another species. In the cold Gulf of St. Lawrence researchers saw the eels they were tracking and studying disappear before they were able to see where they would go to spawn. Turns out that porbeagle sharks ate the unfortunate research objects.

The researchers, as part of the Ocean Tracking Network’s investigation to uncover the eels’ pathway through the Gulf to spawning grounds in the Sargasso Sea— a journey that has mystified scientists for over a century, hoped to track their eels right into the Sea. So they could precisely document spawning areas. Eight eels from the St. Lawrence River in Quebec were tagged with satellite “pop-up tags.”

All eight tags detached from the eels and surfaced prematurely, suggesting the eels’ untimely death.

Julian Dodson, professor at Laval University and principal investigator, coauthored the study told Underwater Times: “Both species are in trouble, and measures to conserve one may well be at odds with efforts to protect the other. What we really need now are studies to quantify just how important eels are in the diets of sharks and just what impact shark predation has on eel abundance.”

Read more at Underwater Times.

Oceanic whitetip shark. Photo: Flickr/Creative Commons- Cold Water Diver

NASSAU (BAHAMAS)- Research indicated that although their reputation for being open ocean dwellers oceanic whitetip sharks (Carcharhinus longimanus ) spend most of their lives in a certain area. In the case of a research by an US-led team of marine biologists, the Bahamas.

The researchers also found that the sharks spent about 68 percent of their time in Bahamian waters, which is good news for conservationists since the Bahamas have strictly protected the sharks for the past two decades.The oceanic whitetip shark is one of the most severely overexploited shark species, it is also among the least studied because it lives much of its life far from land in the open ocean.

According to their report in the online journal PLOS ONE, the team attached tracking tags to one male and 10 female mature oceanic whitetip sharks near the Bahamas in May 2011 and recorded the sharks’ behavior over several different intervals. The tags transmitted their depth, water temperature and location for pre-programmed periods of time.

The team found that five of the sharks made long-distance travels far away from the chain of tropical islands, with one even traveling as far out as Bermuda. All of these were mature female sharks that eventually returned to the Bahamas, providing the first evidence of return-migration for these large marine predators. Before this study very few of these sharks had been fitted with satellite tags, and the data the team obtained will help establish new conservation measures.

Co-Captain Jody Whitworth and master of the M.V. Ocearch Brett McBride prepare to stabilize great white shark, Amy, before taking measurements, blood and securing a real-time technology tag. Photo courtesy of Ocearch.

HAMILTON (BERMUDA)- Mary Lee, a 16ft, 3,456lbs great white shark, is a celebrity on the internet by now. Ocearch has been tracking the big fish since it was first tagged off the coast of Cape Cod (northeast coast USA) last September.

Where the shark is swimming can be seen at the Ocearch website and Mary Lee has thousands of followers. Last she is tracked just over 100 miles to the island’s north and could reach Bermuda’s coast within the next 24 hours. Maybe Mary Lee is attracted to Bermuda’s waters by shoals of giant tuna.

For the last months she has been had been monitored in shallow waters along the Florida coastline, probably while hunting for seals, and spotted off  other east coast state shores. However she has been swimming further from the US coast, moving in a southerly direction towards Bermuda.

Great white sharks can be found in almost all coastal and offshore waters, including the northeast Atlantic, and can reach a length of more than 20ft.

JEDDAH (SAUDI ARABIA)- The numbers of sharks in the Red Sea are rapidly declining. There is too little information on them because of lack of research. Researcher Julia Spät, of the Red Sea Research Centre of the King Abdullah University in Jeddah, conducts a research project about the status of sharks in the Red Sea.

Spät found surprisingly low numbers of sharks in the water. She used BRUVs (Baited remote underwater video surveys were developed in Australia, and are now used around the world for a variety of projects. By attracting fish into the field of view of a remotely-controlled camera, the technique records diversity, abundance and behaviour of species), long-line sampling, and market survey data with information from ongoing shark tagging and genetic studies. B

BRUVS in Saudi Arabian inshore and offshore reefs, in conjunction with long-line surveys, revealed a dramatic lack of reef-associated sharks. Catch per unit effort for Saudi Arabian Red Sea BRUVS ranges between 10 – 60 times lower than data available for the Atlantic, Pacific and Indian Ocean. Despite this, relatively large quantities of reef-associated and pelagic sharks could be found in the fish markets in the region, suggesting heavy fishing pressure on existing populations.

The collected data will help the establishment of a baseline on the current status of Red Sea shark populations, serving as a foundation for future studies on these historically overlooked stocks. This research is ongoing.

Read more at the Dutch Shark Society. Or see the video below on how the BRUVs work.