Posts Tagged ‘bottlenose dolphin’

Lethargic Dolphin Nov. 2015

Written by Tursiops. Posted in bottlenose dolphin photo ID, Cetacean Studies, Uncategorized

In August, 2015, during a routine atlantic bottlenose dolphin photo-ID survey, Keith Rittmaster and Josh Summers of nc maritime museum / cape lookout studies encountered a dolphin intermittently rafting lazily at the surface in Back Sound. It appeared to be an unusual behavior but we could not determine a problem so we photographed the bottlenose dolphin and continued on. It was subsequently reported by boaters in the same area in August because the behavior was conspicuous.

Then in early November, 2015 we received multiple reports of a tursiops truncatus (bottlenose dolphin) “disabled”, “dying”, “with a shredded tail”, and ultimately the last report (as of this writing) on November 5th, 2015 was that it was “dead floating upright” in Beaufort Inlet. Dead dolphins don’t float upright and we found what was reported as “dead” on November 5th very much alive, and its behavior recalled our August encounter in Back Sound. But again, not being able to determine a problem, we took photographs and moved on.

Subsequent examination of photos from the 2 encounters confirmed our suspicion that the dolphin we saw Nov. 5th in Beaufort Inlet was the same individual as the one we saw in Back Sound in August. Also evident in the dolphin identification image above [or below?] is 1) it appeared skinnier in November, 2) the injury on its left side in August has healed, and 3) it had fewer Xenobalanus barnacles on its dorsal fin in November. What was reported as a “shredded tail” was actually barnacles on the trailing edge of its tail (see photo).lethargic-dolphin-web-credit Tt-Xeno-flukes-web-credit

Fin whale, and “Onion” returns, Nov.16, 2015

Written by Tursiops. Posted in bottlenose dolphin photo ID, Cape Lookout Studies Program, Cetacean Studies, Marine Mammal Stranding Network, Sighting Report

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Today was an amazing day for the crew of Spyhop. The day started out with 2015’s first sighting of “Onion” here in Beaufort. While out for our regular bottlenose dolphin photo ID survey we encountered him  in the estuary near Phillips Island. He appears to be in good condition, and seems to be in the company of a new companion.

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We continued out to the ocean, as weather conditions were perfect. No other groups of bottlenose dolphins were seen off Shackleford banks. However, several blows from whales were visible in the distance. Heading back into Beaufort inlet we spotted a very unusual sight…A Fin whale (Balaenoptera physalus) just off of Atlantic Beach! This encounter is highly unusual as Fin whales are rarely sighted south of Hatteras in NC or near the beach in shallow water. While photographing this animal for documentation and possible photo identification we sighted a humpback whale, also very near the beach and a short distance away near the AB circle. Unfortunately we did not have the opportunity to photograph this animal. However, on our way back to the dock we encountered yet another humpback whale only slightly farther offshore of Ft Macon!

fin whalefin whale


Fin whale top left and right, Humpback whale below:
humpback whale

Nov. 11, 2015 Dolphin Photo ID

Written by Tursiops. Posted in bottlenose dolphin photo ID, Cape Lookout Studies Program

 

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Beautiful weather allowed us to go out today on our cape lookout studies program boat “Spyhop” and do our usual bottlenose dolphin survey and photo ID.  Just a few minutes after leaving the Gallant’s channel dock we encountered our first group of approx. 15 animals in the estuary. We recognized a few of our winter “regulars”, among them at least 3-4 mother/calf pairs. The next group was spotted in the ocean off the west end of Shackleford, including freeze brand (FB) #402. Freeze brand animals have been previously captured and marked with numbers to help with dolphin research and identification. A lot can be learned from the sightings of these animals. The third group we saw was fairly large, but due to deteriorating weather conditions we decided not to attempt photos. Inside Cape Lookout Bight we saw a single bottlenose dolphin and surprisingly (for this time of year) several sea turtles, one identified as a large Loggerhead. We had hoped for another sighting of the humpback whale repeatedly seen in the area over the last few weeks, and last photographed by us on Nov. 5, 2015.

Here are today’s “best of” bottlenose dolphin dorsal fin photos:

bottlenose dolphin fin photos

Dolphin Epimelitic Behavior, Nov. 1, 2015

Written by Tursiops. Posted in bottlenose dolphin photo ID, Conservation, Marine Mammal Stranding Network, Sighting Report, Uncategorized

On Sunday, Nov. 1st, Katrina Smith reported a floating dead north carolina dolphin in the Newport River near the ICW at the Morehead Beaufort Yacht Club. Upon arrival, Vicky Thayer (NCDMF and NCSU CMAST) and Keith Rittmaster (NCMM) of the NC Marine Mammal Stranding Network noticed it was being supported and moved by another dolphin, a behavior termed “epimeletic”. After approximately 90 minutes of taking photos and video, and seeking help, they (with volunteer Nelson Owens) brought the dead dolphin carcass onto Lee Sykes’ TowBoat US boat near the Morehead/Beaufort high-rise bridge 5 kilometers from where it was initially sighted. After a brief examine, they put it in the CMAST freezer for future necropsy. The most interesting aspect about this case so far is that the dead dolphin, the one being supported and pushed, was a non-lactating adult female. This is unusual because such epimeletic behavior has often been directed towards dead calves, but not towards an adult dolphin as far as we know.

Both bottlenose dolphins are in the nc maritime museum dorsal fin photo-ID catalog, although neither has been seen often. An upcoming necropsy as part of our ongoing dolphin research will yield more information about the dead dolphin, and hopefully future sightings of the “pusher” will teach us more about that dolphin as well.TBUS-VT-NO-Tt-web-credit

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Young male bottlenose dolphin strands at Emerald Isle

Written by Tursiops. Posted in Marine Mammal Stranding Network

On October 19, 2012, a fresh dead bottlenose dolphin was reported floating near Bogue Sound at Emerald Isle.  NC Maritime Museum volunteers David and Bobbi Brown assisted Dr. Victoria Thayer from the NC Division of Marine Fisheries and NC Maritime Museum Natural Science Curator Keith Rittmaster in retrieving the carcass which was frozen for later analysis.  The carcass (#KAR030) was used as a valuable dolphin research and training tool for volunteers and students.  A careful exam and subsequent necropsy revealed fresh monofilament line scars from a gill net on all appendages of the otherwise healthy juvenile male bottlenose dolphin. The marine mammal stranding network reminds you to please make use of the fishing line recycle bins located along the coast.retrieving KAR030KAR030 rt pec linesgroup necr KAR030 capt

Cetacean populations show regional differences.

Written by Tursiops. Posted in Cetacean Studies

Tursiops truncatus feeding technique

Florida bottlenose dolphins stir up mud “nets’ to corral fish (from BBC’s “Life”)

In the short time I’ve been volunteering for the Cape lookout Studies Program, I’ve learned a lot about how our local dolphins behave in ways that are not consistent throughout the world. While researchers are still learning the “whys” for these differences – it’s seems clear to me that cetaceans around the world have developed some interesting behavioral differences in different parts of the world. For example, some bottlenose dolphins chase fish up on shore, and others stir up mud to corral fish and then feed as their prey try to jump out of the nets.

Sri Lanka’s Unorthodox Whales

Which brings us to the blue whales in the Indian Ocean off the southern coast of Sri Lanka. They don’t follow the migration patterns observed in most blue whale populations.

A young bottlenose dolphin dead with multiple entanglements

Written by Keith_Rittmaster. Posted in Marine Mammal Stranding Network, monofilament recycling

            On October 7th, 2011, Kat Fourhman of the NC Aquarium at Roanoke Island responded to a stranding of a dead bottlenose dolphin on the shore of Roanoke Sound near Manteo, NC.  Paul Doshkov of Cape Hatteras National Seashore assisted with the investigation.  It was a 175cm (5’ 9”) male.  At that size he would have been around 2 years old, still nursing, growing fast.  Monofilament line from 2 different types of gill nets surrounded the rostrum and left pectoral fin. 

Bottlenose Dolphin

Written by Tursiops. Posted in Marine Mammal Field Guide

Dolphin jumping in the Estuary

Bottlenose dolphin jumping in the Estuary.

Tursiops truncatus

Adult Length Range: 1.9 – 3.8m Light gray to black, fading to white on the belly. They have a short snout extending forward from the melon.

Dolphin catching fish

Grab it! A dolphin tries to catch a jumping fish. Photo by Leigh Torres

Bottlenose dolphins (Tursiops truncatus) are the most common marine mammal in the coastal and estuarine waters near Cape Lookout and Beaufort, NC.

Bottlenose dolphin are opportunistic feeders and will hunt whatever is most abundant. They are highly adaptable and congregate in groups. Some males bond in groups of 2 or 3 and mother and calf bonds are usually strong.

25 second hydrophone recording sound clip of 17 bottlenose dolphins off Shackleford Banks. Click here for ringtone or here for iPhone m4r.

North Carolinians have related to dolphins in a variety of ways ranging from commercial dolphin net fisheries (late 1700s-1920s, used primarily for oil, leather, and fertilizer) to conservation of this depleted and federally protected population.

Mom and calf, bottlenose dolphin

Today, threats to dolphins include unintentional entanglement in commercial and recreational fishing gear, ingestion of litter, contamination of food sources, boat strikes, and intentional (but illegal) feeding of dolphin by boaters.

Researchers at the NC Maritime Museum have been using photo-identification since 1985 to study the local bottlenose dolphins.

Jerry, a stranded bottlenose dolphin

Written by Tursiops. Posted in Marine Mammal Stranding Network

Jerry, a stranded bottlenose dolphin

June 14, 2003

On June 14, 2003 I (Allen), Tabbie Merrills, Hugh Wilde, and Buddy Nance, were loading Spyhop at the old Coast Guard docks when Tabbie saw a dolphin swimming in the Bight heading toward a shallow area. As we watched the dolphin swam up to the shore. At first we didn’t think much about this because we often see dolphins in shallow water feeding. But when some kids approached the dolphin from the shore and the dolphin appeared to remain in the same place we knew something was wrong. We immediately placed a call to the Marine Mammal Stranding Network to report a live stranding.

After talking with the local stranding coordinator, Gretchen Lovewell, it was decided to seek the advice of a veterinarian with the NCSU veterinarian school, Dr. Craig Harms. As luck would have it the Dr. Harms had kayaked to the Cape earlier that morning to climb the lighthouse and just happened to check his messages. We were all surprised to see him come kayaking up.

As Dr. Harms examined the dolphin we saw that a shark had bitten it and that it was listing to one side. It was a big dolphin and highly unlikely to have been bitten by a shark unless it was already weak. Dr. Harms thought this could be good candidate for rehabilitation so the decision was made to transport the dolphin to the NOAA Lab on Pivers Island.

We loaded the dolphin on to Haywood Holderness’s boat and transported the dolphin to Harkers Island where NOAA personnel Aleta Hohn , Annie Gorgone, Gretchen Lovewell, and Ari Friedlander from Duke met us. We loaded the dolphin into the back of a pickup truck, covered him with wet towels and transported him to the NOAA lab. Four of us rode in the back spraying him with water. At the NOAA Lab we unloaded the dolphin into a temporary pool. Dr. Harms took blood samples for analysis and tube fed him some liquids.

It was necessary for someone to be in the pool with him at all times to help him keep his head above water to breath and to keep him from listing to one side. Tabbie started contacting possible volunteers and making an around the clock schedule. We had volunteers from the local community, NOAA, Duke Marine Lab, NC Maritime Museum, and NCSU School of Veterinarian Medicine.

It was also necessary for us to provide some fish for him to eat. Hugh provided some frozen spots from his freezer. Leslie from William Smith Seafood in Beaufort kindly offered to help provide fish for food. Keith also provided some food, trashing his best cast net in the process. The dolphin would not eat so Dr. Harms made a fish slurry and tube fed him.

When the blood samples came back it was obvious that we had a very sick dolphin on our hands, but nobody gave up. Dr. Harms contacted the NCSU Veterinarian School and 2 veterinarian students came down from Raleigh to assist. Dr. Harms did everything possible to help the dolphin and spent countless hours with him, but he was an old sick dolphin and it was his time. When he died 3 days later, on June 17th, it was a sad time for all the people that had worked so hard to try and save him. The necropsy confirmed that he was a very sick dolphin.

Thanks to all the people that helped.







The rearticulation of a bottlenose dolphin skeleton

Written by Tursiops. Posted in Cetacean Studies

by Keith Rittmaster and Leonard DeDuke, 5 March, 1997

bottlenose dolphin skeleton     On May 11, 1993, Keith Rittmaster, Natural Science Curator of the NC Maritime Museum, discovered a dead bottlenose dolphin carcass washed ashore at Cape Lookout. Keith performed a necropsy to determine the sex, approximate age, possible cause of death, and to take tissue samples and measurements. It was a post-partum adult female, 260 cm long. The cause of death was not determined. Tissue samples (gonads and stomach) were sent to the Beaufort NMFS lab for analysis. Then students from Halifax Academy, Roanoke Rapids, NC assisted Keith in burying the carcass under approximately 1 meter of sand behind the primary dune on 1/4″ mesh hardware cloth.

     On May 21, 1994, students from Halifax Academy returned to help Keith exhume the grave. After a year, very little flesh or residual tissue remained. 16 people divided into teams of 2-3 focused on specific aspects of the skeleton. Each arcade of teeth was pressed into a labeled piece of styrofoam. The vertebral column was strung together in order with nylon twine. Hardware cloth envelopes were made and labeled for the flippers, hyoid bones, sternebrae, caudal vertebrae, and pelvic bones. Ribs and costal bones were labeled and tied together in order. The chevrons were assembled in order, photographed, labeled, and placed in a hardware cloth envelope.

     Keith brought the bones back to the museum, scrubbed them, and soaked them for two weeks in a weak (10%) solution of household ammonia. Then they were air dried in the sun.

     Museum Volunteer Leonard DeDuke undertook the task of rearticulating the bottlenose dolphin skeleton with advice from Charley Potter from the Smithsonian Institution, Bill McLellan and Ann Pabst from UNC Wilmington, Sentiel Rommel, and various publications on the subject. A 1/4″ stainless steel rod runs through the entire length of the vertebral column. Felt pads were used to represent the intervertebral discs. Wires and Marine Tex adhesive were used to attach most of the other bones together.

     Notice there are no bones in the lateral extensions of the tail (flukes) nor in the dorsal fin which are soft tissue in the living specimen. These appendages are highly vascular and used for swimming and thermoregulation. Also notice that near the back of the vertebral column that some of the vertebrae are fused. This may have been a result of an injury or disease, and perhaps a contributing factor in the dolphin’s death, or, as is often the case in dolphins, a normal condition of aging. Also note one of the ribs on the dolphin’s right side was fractured. This was repaired in the rearticulation, but may have contributed to the dolphins’ death. On the same rib notice a previous fracture that was healed in life.

     A rearticulated bottlenose dolphin skeleton such as this one has tremendous educational and scientific value. It provides students and scientists the opportunity to study the evolution, comparative anatomy, and bone disorders of these animals. Public displays are an excellent means for increasing public awareness of marine mammals. Since the dolphin is a mammal, it’s bones are similar to other mammals, including humans. There are, of course, some differences between dolphin skeletons and other mammals. One of those differences is the presence of the chevron bones on the undersurface of the caudal (or tail) vertebrae. These bones serve as sites for muscle attachment used in the downstroke in swimming. Notice that the flipper has the similar bones (humerus, radius, ulna, phalanges) found in other mammals, including humans. These bones, however, are relatively smaller in the dolphin and reflect adaptations for life in a marine environment.

     The study of a specimen such as this one also assists in the behavioral interpretations of observations in the wild. For example, a dolphin’s physical limitations are not obvious in the wild but an understanding of these limitations through skeletal studies will help us understand the relationships between biology, anatomy, and behavior.

     To complete this project, from the necropsy on the beach to the final hanging of the bottlenose dolphin skeleton display took approximately 300 people hours. The cost of materials was approximately $300. Leonard is not interested in rearticulating another bottlenose dolphin skeleton but said he may be interested in trying a large whale next.