Showing posts with label Dolphins. Show all posts
Showing posts with label Dolphins. Show all posts

Thursday, February 2, 2012

True Confessions of a Dolphin-Loving Marine Biologist by Miriam Goldstein

It seems as though most people have some sort of cultural guilt; we feel bad about not calling our parents regularly, about forgetting our brother’s birthday, or we chow down on half the gallon of ice-cream while watching the season finale of Glee (yes, I cried).  I have an additional guilty secret – I am one of the few marine biologists that actually studies dolphins. And not cold-water dolphins either – dolphins that frolic under tropical Hawaiian sunsets. It really is a secret, at least from casual acquaintances.  When my dentist asks me what I do, I usually tell her I spend a lot of time on the computer.  When the guy next to me on the airplane strikes up a conversation, I generally tell him I study underwater sound.

Why all this guilt?  Well, when you think about all of the millions of amazing creatures in the ocean, dolphins make up a very very tiny percent.  And yet, it seems as though they get the majority of the love.  Everyone loves dolphins, but there is so much more out there that deserves our love, respect, and interest.  I mean, there are tunicates build their own house every day and are one of the inspirations for the alien in Alien! How cool is that?

So, if I feel so guilty about cetaceans (the group that includes dolphins and whales), why am I doing it?  Well, despite the love, we really don’t know that much about whales and dolphins.  We don’t know where they are most of the time, we have only a hazy idea of what some of them are eating, and we don’t know a lot about their breeding habits.  No one has ever seen a humpbacked whale, well… hump.  A lot of cetaceans are in big trouble, like the North Atlantic Right whale and the Yangtze River Porpoise.  The ones that are in trouble (like almost all other endangered life on earth) are endangered because of humans.  North Atlantic Right Whales get hit and killed by big ships. Yangtze porpoises, which have to be one of the cutest animals ever, are being polluted and dammed into oblivion, just like their neighbors, the Yangtze river dolphin, which is now extinct.   The beautiful vaquita porpoise is among the 50 most endangered animals in the world.  So yes, there are a lot of other fascinating things to study in the ocean, but there are a lot of good reasons to study dolphins, too. Also, I love them, even if admitting it can be like admitting I like Twilight (which I am SO not admitting).

Photo of outstretched hands holding a red dolphin.
This is how I sometimes feel when I’m talking to non-dolphin-studying marine biologists.

Wednesday, January 18, 2012

Irrawaddy Dolphins, Orcaella brevirostris

Description & Behavior

Irrawaddy dolphins, Orcaella brevirostris (Owen in Gray, 1866), aka Mekong or Mahakam River dolphin, reach 2-2.75 external m in length. The color of Irrawaddy dolphins is dark blue to dark gray ranging to pale gray, with a pale ventral (under) side. They have a high rounded forehead and no beak. Their U-shaped blowhole is located to the left of the midline on their dorsal (upper) side and opens to the front, unlike other species. They have a small, blunt, rounded triangular dorsal fin and large flippers. Like other river dolphins their neck is highly flexible, which enables them to forage in shallow water. They have narrow, pointed, peg-like teeth about 1 cm in length in both their upper and lower jaws. Two unique anatomical features of Irrawaddy dolphins are that they do not have a cardiac sphincter external and the stomach is subdivided into compartments. They are not acrobatic dolphins and are not known to bowride external; however they have been observed leaping from the water.
Irrawaddy dolphins dive for an average of 30-60 seconds but longer dives have been recorded of up to 12 minutes. Although they are generally slow swimmers, a swim rate of 25 external kph was recorded for one individual. This species is usually seen in small groups consisting of <6 animals, but groups of between 10-15 have been reported. This species spends most of their time feeding. They display a unique behavior of expelling a stream of water up to 1.5 external m which is thought to be used to herd fish. Fishermen have reported Irrawaddy river dolphins stunning large fish then playing with them before they eat them.

Irrawaddy dolphins are not thought to communicate through vocal signals.

World Range & Habitat

Irrawaddy dolphins, Orcaella brevirostris, are found in the coastal waters and large rivers of Southeast Asia, Northern Australia, and Papua New Guinea. They prefer coastal, brackish, and fresh water of the tropical and sub-tropical Indo-Pacific.

Feeding Behavior (Ecology)

Irrawaddy dolphins, Orcaella brevirostris, feed on fishes, crustaceans, cephalopods, and fish eggs. Two species of cyprinid fish external, Cirrihinus siamensis and Paralaubuca typus, are thought to be important food sources for Irrawaddy dolphins found in northeastern Cambodia and Laos. Carp is the primary species consumed in other areas.

Life History

Little is known about the reproductive habits of Irrawaddy dolphins. It is thought that they reach sexual maturity when they are around 4-6 years old. Their mating season is believed to occur between April-June in the Semayang Lake/Mahakam River area of Kalimantan, Indonesia, based on the birth of calves born in captivity in Jakarta between July-December. Their gestation period is estimated at about 14 months. Newborns measured following birth in captivity were 96 external cm long and weighed 12.3 external kg. During their first 7 months, calves increased in length by 57 external cm (59%) and in weight by 32.7 external kg (266%). One calf was nursed for about 2 years, although it began consuming fish at 6 months.

Experts Perplexed by 60 Dolphins Stranded on Cape Cod by Lauren Keiper Reuters

Animal welfare advocates are perplexed by dozens of dolphins swimming onto land along the scenic Cape Cod shores south of Boston beginning late last week, one of the largest cases of dolphins stranding themselves in years.

About 60 animals have been stranded along 25 miles of Cape Cod coastline since Thursday, according to the International Fund for Animal Welfare (IFAW).

So far, 19 dolphins have been rescued and released, with some of the 27 dolphins stranded alive unable to survive, said Katie Moore, manager for the group's marine mammal rescue and research. She estimated another 32 washed ashore already dead.

She said the pattern this year is unlike past years, when just one dolphin or a group would be found on a single beach.

"It feels like stranding after stranding after stranding," she said. "It's definitely out of the ordinary."

The dolphins began beaching themselves on Thursday, with a single dolphin stranded near the town of Wellfleet, Massachusetts, said Kerry Branon, a spokeswoman for IFAW.

On Saturday, the busiest day for rescuers, at least 37 dolphin were found spanning five towns along Cape Cod, Branon said.

January through April is the typical season for multiple beaching of dolphins, Branon said.

Cape Cod is among the top locations for the phenomenon worldwide, she said. Beaching of dolphins has been happening for centuries, but researchers are still trying to determine what brings the dolphins to Cape Cod Bay this time of year.

The group actions tend to happen, in part, because dolphins operate with a group mentality, where many others may follow one animal toward shallow water, IFAW said.

Monday, January 2, 2012

425 Dolphins Taken In Taiji Japan by Elizabeth Batt


Although the start of the dolphin drive season in Taiji, Japan was delayed by Typhoon Talas, midway through the season 425 dolphins have been driven into the cove.

Six species of dolphin have been affected since the dolphin drives commenced on September 01 in what has been a tense time for both fishermen and activists on the ground in Taiji. Despite the slow start to the season which echoed throughout the month of September, by November and December, the dolphins received little respite. 

When fishermen berthed their boats for the holiday season on Dec. 22, 425 dolphins had been herded into the cove. Of these, reports Ceta-Base.com, "354 were killed, 38 were released, 28 were live-capture and five have an unknown status." It is a fraction of the 2,165 dolphin quota set for the 2011/12 season by the Taiji Fishery Union (FU), yet activists mourn every loss. The total quota of dolphins granted to fishermen when divided by species includes some 652 bottlenose; 450 striped; 400 spotted; 275 Risso's, 184 long-finned pilot whales, 134 Pacific white-sided dolphins and 70 false killer whales.
 
For those unfamiliar with the Taiji dolphin drive season which takes place annually between September and March, it revolves around a small group of fishermen who operate under the umbrella of the FU in the Wakayama Prefecture of Japan. Weather allowing, up to 12 drive boats leave the harbor each day in search of dolphin pods. These drive boats, called banger boats by activists, are speedy vessels specifically designed to outmatch a dolphin's speed.

When boats locate a pod, metal poles are lowered into the water and hit repeatedly. The metallic clanging interferes with the dolphin's sonar, confusing them. Now disorientated, the dolphins are easily driven towards the harbor and into the cove. The fishermen are further aided in their quest by the topography of the seafloor which creates a natural funnel that helps herd the mammals towards shore. 
 
Once the dolphins are inside the cove, the entrance to the ocean is sealed off with nets, making escape impossible. A few dolphins may be selected for sale to captive marine mammal facilties around the world but the majority are slaughtered for meat. Dolphin meat has been described by one conservation group in Japan as little more than toxic waste. Yet despite being laden with mercury and other pollutants, the meat is sold in Japanese supermarkets. 



Sunday, November 20, 2011

Tuna Fishing Film Shows Whales, Dolphins And Manta Rays Slaughtered (Graphic Video)

A shocking Greenpeace video has revealed the appalling slaughter of marine life during tuna fishing. A tuna industry whistleblower spoke out to expose the routine killing of whales, dolphins and manta rays.

The never-before-seen footage shows graphic images shot aboard a Pacific fishing vessel. The ship uses fishing aggregated devices, man-made floating objects used to attract fish.

UK tuna giants, John West and Princes have agreed to not source tuna from operations using FADs, as well as all major British supermarkets. However Greenpeace warns this is not enough.

“This shocking video is a wake-up call: we as consumers, can demand that retailers give shelf-space only to responsibly-caught tuna. Without significant changes to global fishing practices and more protected marine reserves across the world’s seas, we will literally fish away future tuna supplies, jobs and healthy oceans.” said Casson Trenor, Greenpeace USA oceans campaigner.

Wednesday, November 16, 2011

This picture was taken by Lori Mazzuca in Hawaii. She said that the dolphin and humpback whale were playing gently together. The game seemed to be about how long the dolphin could stay atop the whale's head while the whale swam. When the dolphin finally slipped off it joined another dolphin and they began to leap with joy.

Dolphins are cute. Whales are appealing. Together, the two are irresistible.
This picture showed up on the Facebook page for The Whale and Dolphin People Project, an unconventional group that aims to be "a game-changer campaign to stop the killing of whales & dolphins by changing their status from animal to people."

Friday, November 11, 2011

The Taiji Massacre

There are a few countries which still take part in inhumane dolphin hunts. These countries include Brazil, Peru the Solomon Islands and Denmark in specific the Faroe Islands.

However the largest massacre of dolphins takes place in the waters surrounding Japan, where more than 20,000 of these marine mammals are killed annually. Usually these sensitive animals are harpooned with barbed spears, however a large number of dolphins are captured and murdered in a process called “drive fishing” or “oikomi” as it is known in Japanese.

Drive fishing occurs in mainly coastal towns such as Futo and Taiji. The small fishing town of Taiji lies on the tip of a peninsular that runs in to the Pacific Ocean and is home to the largest dolphin massacre on the face of the planet. During the “driving” season which runs from October to March, in this small picturesque town alone up to 2,500 dolphins are viciously hacked to death every year.

Thursday, November 10, 2011

When the Best Tool Is an Animal

The U.S. Navy Marine Mammal Program (NMMP), based in San Diego, CA, began in 1960 when the military examined the Pacific White-sided Dolphin, trying to figure out the secret to its hydrodynamic body with the aim of improving torpedo performance. (Given 1960s technology, the NMMP never managed to solve the puzzle.) That later expanded to other marine mammals of the Pacific, especially other dolphins and California sea lions, which led to the discovery that these animals are not only trainable but fairly reliable even while untethered in the open ocean.

NMMP has been a controversial program, but the Navy insists that the program complies with all available statutes, including the Marine Mammal Protection Act and the Animal Welfare Act. The NMMP also states that, despite rumors, marine mammals have never and will never be used as weapons themselves. No attack dolphins.

So what does the NMMP do now? Dolphins are used as undersea mine detectors, even finding more than 100 in the Persian Gulf during the Iraq War in 2003. Dolphins and sea lions are used as sentries to find and alert the military to unauthorized swimmers and divers, and sea lions are used to retrieve objects from the ocean depths (at this they outperform human and robotic swimmers by a fair margin).