‘WELL SPOTTED’ (2): ATLANTIC SPOTTED DOLPHINS IN ABACO


Atlantic Spotted Dolphins in Abaco Waters (BMMRO)

‘WELL SPOTTED’ (2): ATLANTIC SPOTTED DOLPHINS IN ABACO

No sooner have I posted about PANTROPICAL SPOTTED DOLPHINS sighted during the current BMMRO whale research program, than the other Bahamas spotted dolphin species shows up as well. These are the more numerous Atlantic Spotteds Stenella frontalis, more confined in range (as the names suggest) than the Pantropicals. 

Atlantic Spotted Dolphins in Abaco Waters (BMMRO)

The BMMRO caption reads “Atlantic spotted dolphins today! Small social group playing with sargassum – they swam past what looked like a plastic mattress cover – one dolphin whacked it with its tail as it swam by…”

Atlantic Spotted Dolphins in Abaco Waters (BMMRO)

Just because it can…Atlantic Spotted Dolphin leaping in Abaco Waters (BMMRO)

RUBBISHING RUBBISH: A RANT

Behold a large plastic bag, made by humans and dumped by humans into a place that is not theirs to use as a trash repository. It will take some 500 years to break down completely. But when people say that they don’t really mean it will have harmlessly disappeared over that period and become salt water. Far rom it. It will just break down into smaller and smaller pieces, to bite-sized bits for turtle, fish and seabirds who will idiotically mistake them for food (duh!), then to micro-plastic that will become part of the evolving plastic soup that will be ingested by tiny sea creatures and coat the reefs in polyethylene gunk. [End of rant. Ed.]

Atlantic Spotted Dolphins in Abaco Waters - marine trash (BMMRO)

Behold an Atlantic Spotted Dolphin giving the bag a passing whack with its tail. It won’t do anything to help with marine pollution, but is shows a robust disdain for a piece of man-made rubbish that has made it into the creature’s home environment.

Atlantic Spotted Dolphins in Abaco Waters - marine trash (BMMRO)

Below is a short GoPro shoot of a pair of ASDs, that I took from the BMMRO research boat last year. Marvel at the grace and elegance of these beautiful animals as they swim just below the surface (wonder, too, at the incompetence of the cameraperson who, to be fair, was leaning over the side of the RHIB with the camera on a stick…)

All photos BMMRO; video from the Rolling Harbour achives, intemperate rant all my own

‘WELL SPOTTED’: PANTROPICAL SPOTTED DOLPHINS IN ABACO


Pan-tropical Spotted Dolphins, Abaco Bahamas (BMMRO)

‘WELL SPOTTED’: PANTROPICAL SPOTTED DOLPHINS IN ABACO

Two species of spotted dolphin are found in Bahamas waters. The most common is the ATLANTIC SPOTTED DOLPHIN Stenella frontalis, a species confined to the Atlantic. Less commonly seen – though with a global range – are Pantropical Spotted Dolphins Stenella attenuata

Pan-tropical Spotted Dolphins, Abaco Bahamas (BMMRO)

The BMMRO research boat is out whale-spotting right now, and the team is finding a good variety of cetacean species, from dolphins right up to SPERM WHALE mother and calves. A couple of days ago, the pantropicals surfaced and these great shots of them were taken.

Pan-tropical Spotted Dolphins, Abaco Bahamas (BMMRO)

The two spotted dolphin species are very similar to the untrained eye. Identification is further complicated by the fact that both species start life without spots and go through stages ranging from no spots at all to completely spotted. These stages are sometimes referred to as ‘two-tone, speckled, mottled, and fused’. The pantropicals are relatively small, reaching lengths up to 7 feet and weighing c250 pounds at adulthood. Their beaks are longer and more slender than the familiar but larger bottlenose dolphin. The beak has a white tip, a useful identifier.

Atlantic Spotted and Pantropical Spotted range maps for comparison

The pantropicals favour shallower water by day, and at night they move to deeper water where they can dive down for food such as squid. Although they are IUCN listed as ‘Least Concern’ and their world-wide numbers are estimated to be abundant, they face the usual man-related threats to the species throughout their range, especially in the Pacific region. As we see time after time, complacency can turn to concern in a very short time.

Pan-tropical Spotted Dolphins, Abaco Bahamas (BMMRO)

THREATS TO THE SPECIES

  • Entanglement in fishing gear – captured as bycatch in the course of commercial fishing
  • Entangled in discarded fishing gear
  • Illegal feeding and harassment – this is a problem in particular locations eg Hawaii
  • Overexposure to and interaction with eager tourists in inshore areas
  • Hunting – these dolphins are prolifically hunted for food in several parts of the world
  • Hunting – they are caught ‘accidentally’ in large numbers in nets set for tuna
  • Persecution in eastern tropical Pacific fisheries, according to WDC
  • Pollution, plastic ingestion etc – basically, mankind’s negligence over 60 years or so
  • General habitat degradation, disturbance and marine noise pollution – mankind again

Pan-tropical Spotted Dolphins, Abaco Bahamas (BMMRO)Pan-tropical Spotted Dolphins, Abaco Bahamas (BMMRO)

Credits: BMMRO for all photos; research credits NOAA; WDC

DOLPHINS DISPORTING IN THE BAHAMAS


Atlantic Spotted Dolphin, Bahamas (BMMRO)

DOLPHINS DISPORTING IN THE BAHAMAS

‘Disporting’. Not a word I’ve used very often. Or possibly ever. It looks a bit like ‘unsporting’, which is emphatically what dolphins are not. Basically, it just describes what dolphins are doing when you see them on the surface: amusing themselves, frolicking around in the waves, and simply enjoying themselves.Bottlenose Dolphin, Bahamas (BMMRO)

True, they are probably keeping an eye out for food… But when you have a group sociably following alongside the boat your are in, moving in front, dropping behind, diving under, and generally playing around, it’s quite hard to believe that these are completely wild creatures. They seem to be performing just for you, simply because they want to. You don’t even have to throw fish at them to earn this free display.

Atlantic Spotted Dolphin, Bahamas (BMMRO)Atlantic Spotted Dolphin, Bahamas (BMMRO) Atlantic Spotted Dolphin, Bahamas (BMMRO)

As is well-known, the BAHAMAS MARINE MAMMAL RESEARCH ORGANISATION (BMMRO) is the custodian for the welfare of these beautiful creatures for the entire Bahamas. However, being based on Abaco and carrying out the majority of the research from the HQ at Sandy Point means that many of the great images that get taken are from Abaco waters. Indeed some are taken within swimming distance (not mine) of the shore.  Bottlenose Dolphin, Bahamas (BMMRO)Bottlenose Dolphin, Bahamas (BMMRO)Bottlenose Dolphin, Bahamas (BMMRO)Bottlenose Dolphin, Bahamas (BMMRO)

The photographs featured here were taken during the last few weeks. Some are of the familiar bottlenose dolphins. The others – with speckled undersides clearly visible in the header image & below – are of Atlantic spotted dolphins. There’s even one of my own taken from the research vessel. Atlantic Spotted Dolphin, Abaco Bahamas (Keith Salvesen)Atlantic Spotted Dolphin, Bahamas (BMMRO)

For the researchers, the most important part of an individual dolphin is its dorsal fin. Unique patterns of cuts and scars mean that each dolphin sighted can be logged and their profiles built up. Some have been found in the same area for many years. They are not usually given jocular names – ‘Davy Jones’, ‘Finny Phil’ or whatever. The first time we went out on the research vessel we were slightly surprised by the practical, scientific calls during a sighting of a dolphin group: “there’s B4 again” and “over there – D5 is back”. All said fondly however – many of the dolphins are old friends.

This dolphin has a notable notch on the dorsal fin with a nick below, & a scar line – with a prominent white scar on the lower front edge Bottlenose Dolphin, Bahamas - Dorsal Fin Damage (BMMRO)

Notice how these 3 dolphins all have quite different fin profiles.  The nearest one’s fin looks unblemished, but has a paler tip. Powerful binoculars and a serious camera can pick out small  differences at a distance that the eye could notBottlenose Dolphin, Bahamas - Dorsal Fin Damage (BMMRO)

Coming soon: Manatees & Man in the Bahamas

All photos (bar one by me) BMMRO, with thanks to Diane & Charlotte, and a tip of the hat to the current interns involved in the research projects (Hi, UK Thomas!)

ATLANTIC SPOTTED DOLPHINS OFF ROCKY POINT, ABACO


Atlantic Spotted Dolphins off Rocky Point, Abaco

This pair was in a group of 8 Atlantic Spotted Dolphins that we encountered yesterday during a day’s expedition on the Bahamas Marine Mammal Research Organisation (BMMRO) research boat. We spent nearly an hour with them, and there will be a longer post about these magnificent creatures in due course. But right now, I’m still in single image posting mode while “on-island”…

Photo: Keith Salvesen / BMMRO

THE BAHAMAS: A STAMPING GROUND FOR DOLPHINS


Dolphin leaping, Abaco (BMMRO)

THE BAHAMAS: A STAMPING GROUND FOR DOLPHINS

I have commented before on the excellent wildlife stamps produced by the Bahamas Philatelic Bureau, and there is a fairly comprehensive page featuring many of the special issues HERE. Recently, dolphins were treated to their own set of stamps, in conjunction with the BMMRO (Bahamas Marine Mammal Research Organisation).  Four dolphin species are showcased, with a fifth species (Risso’s Dolphin) shown on the commemorative Official First Day Cover (replete with the BMMRO logo). The release date was 31 March 2016.

Bahamas Dolphin Stamps 2016

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The stamps are available as sets of 4 or of course individually. In a newsletter earlier this year, the BMMRO included some fascinating information about their valuable work – in particular with whales – and about the individual dolphin species featured in this very special philatelic issue. This was also published by the stamp producers, Pobjoy Mint Stamp Division.

BMMRO is a Bahamian non-profit organisation whose mission is to promote the conservation of marine mammals in The Bahamas through scientific research and educational outreach. Since 1991, BMMRO has been conducting small vessel surveys primarily around Abaco Island to document the occurrence, distribution and abundance of marine mammals in The Bahamas.

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BOTTLENOSE DOLPHINS Tursiops truncatus

These are the most common marine mammals seen on the Bahama banks. It should be noted, however, that there are at least two distinct “breeding populations” or “ecotypes” of this species: coastal bottlenose dolphins that inhabit the shallow waters of the banks; and oceanic bottlenose dolphins found in pelagic waters. These populations diverged genetically several hundred thousand years ago and have since developed different physiological adaptations to their respective marine environments. The coastal ecotype is smaller in length reaching just over 8 feet and has a relatively larger dorsal fin and pectoral fins which helps them to maneuver more readily around rocks and reefs to catch fish, and to regulate their internal body temperature (the temperature of the shallow Bank waters fluctuates much more than the deeper Atlantic Ocean). The coastal dolphins do not travel much beyond the bank edge and live in small resident communities. The deeper diving oceanic ecotype can reach 10 feet or more in length, are usually seen in larger groups and appear to have a more extensive range with movements documented between Abaco, Bimini and Exuma Sound.

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ATLANTIC SPOTTED DOLPHINS Stenella frontalis

These dolphins are not born with spots, but actually accumulate them as they mature, becoming quite mottled-looking as adults. Hence, young spotted dolphins are often confused with bottlenose dolphins, and sometimes the two species will interact, which adds to the confusion. Although they can reach almost the same length as bottlenose dolphins, they have a smaller girth and thus body weight. Atlantic spotted dolphins are a year-round resident species in The Bahamas. Individuals photo-identified 20 years ago in Abaco can still be seen in the same areas today. They are commonly seen in groups of 20-50 dolphins in the oceanic waters where they feed on flying fish and squid, and rarely venture on to the bank. However, along the western edges of Little and Great Bahama Banks this species can regularly be found on the bank during the daytime where they come to rest and socialise.

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PANTROPICAL SPOTTED DOLPHINS Stenella attenuata

This species is more slender in body shape than Atlantic spotted dolphins, and also have a distinctive dark dorsal cape, which sweeps from their rostrum to behind their dorsal fin. Like Atlantic spotted dolphins, they accumulate their spots with age, which allows researchers to readily document age-classes within groups. This species is strictly oceanic in its distribution. Pantropical spotted dolphins are not as frequently sighted as Atlantic spotted dolphins in The Bahamas. They occur in groups of 50-100 dolphins and are often seen engaging in acrobatics, such as making high leaps out of the water, and bow-riding.

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ROUGH-TOOTHED DOLPHINS Steno bredanensis

These dolphins are dark grey in colour with a long beak and prominent white lips. Their lower jaw and belly can sometimes be a pinkish colour. They reach just over 8 feet in length. They are an oceanic species and although appear to be rare in some parts of The Bahamas, can be regularly seen in the Tongue of the Ocean where they occur year round. Some individuals have been re-sighted in this area over the past ten years. They are typically found in groups of about 20 animals, but are sometimes in larger mixed-species aggregations of several hundred dolphins.

Risso's Dolphin - BMMRONot on a stamp but shown on the First Day Cover

RISSO’S DOLPHIN Grampus griseus

These are large light grey dolphins that can reach over 13 feet in length, and have a relatively tall, dark dorsal fin. Adults are typically covered with overlapping white scars caused by the teeth of their con-specifics making them look quite battered. They have a rounded head, lacking a beak, but have a deep vertical crease down the center of the forehead. As they mature, their forehead becomes prominently white, and as such they are one of the easiest species to recognize at sea. Risso’s dolphins are commonly seen in oceanic waters in the northern Bahamas each winter and spring, primarily on the Atlantic side of the islands. It is unknown where these groups range the rest of the year, but some individuals have been seen off Abaco repeatedly over the years.

RELATED POSTS

BAHAMAS WILDLIFE STAMPS PAGE

PHILATELY WILL GET YOU…

ABACO BIRD STAMPS

Bottlenose Dolphins, Rocky Point, Abaco (Keith Salvesen : BMMRO) 7

Credits: BMMRO for relevant text & images except last (RH), Pobjoy Mint, Bahamas Philatelic Bureau

‘SPOTTED IN ABACO WATERS’: PANTROPICAL SPOTTED DOLPHINS


 Spotted Dolphins Abaco Bahamas (BMMRO)

‘SPOTTED IN ABACO WATERS’: PANTROPICAL SPOTTED DOLPHINS

The BMMRO has posted several reports of dolphin and whale activity around the coast of Abaco during August, with some outstanding photos to accompany them. I had been going to post rather generally about this until a couple of days ago, when an unusual dolphin species for the region was… er… spotted and some memorable images taken.

Spotted Dolphins Abaco Bahamas (BMMRO)

These are PANTROPICAL SPOTTED DOLPHINS Stenella attenuata, whose range encircles the globe but at a lower latitude than the far more frequently encountered resident  ATLANTIC SPOTTED DOLPHINS Stenella frontalis. Here are comparative range maps. The rarity of the Pantropical species in the Bahamas is indicated in the BMMRO report of a stranding in 2011 – see below.

ATLANTIC SPOTTED DOLPHIN                                                                    PANTROPICAL SPOTTED DOLPHIN

Verbreitungsgebiet des Zügeldelfins Stenella frontalis.PNG                                                Cetacea range map Pantropical Spotted Dolphin.PNG

Spotted Dolphin Abaco, Bahamas (BMMRO) copy 2

Spotted Dolphins Abaco  Bahamas (BMMRO)Spotted Dolphins  Abaco Bahamas (BMMRO) copy

The pantropical image below is from the BBC archive and not taken in the Bahamas. I’ve included it for illustrative purposes due to the close-up underwater view of the dolphin.Pantropical spotted dolphin (BBC)

This wonderful underwater video of pantropicals is by Jake Levenson, shot from a polecam. Although it is 6 minutes long, I highly recommend it for (a) the stunning views of these creatures at very close quarters (b) the excellent audio quality – you can clearly hear the dolphins communicating with ‘sonar’ clicks and squeaks, and (c) the strange sense of peace you may feel when you have watched it. 

[youtube http://youtu.be/-hXTYe58g34]

PANTROPICAL SPOTTED DOLPHIN STRANDING 2011

In May 2011 a dead dolphin was found on the sandbank at Casaurina Point, Abaco. BMMRO’s scientists established that it was a sub-adult male pantropical spotted dolphin with a stomach full of squid beaks, a known prey for the species. A full necropsy was conducted on the animal and samples were taken for scientific testing to determine the cause of death. At the time the BMMRO reported the find in their quarterly Newsletter:

Pantropical spotted dolphins are commonly found in off-shore waters, although they can be found close to Abaco’s coastline due to the close proximity of deep waters. They can occur in large group sizes of up to 100 animals. Adult males and females reach up to 2.6 m (8.5 ft) and 2.4m (7.9 ft) in length, respectively. Since our efforts began in 1991, BMMRO has records of only 28 sightings of pantropical spotted dolphins in The Bahamas (my rubric), although their cousin species, Atlantic spotted dolphin, is a common resident. This is the first recorded stranding of this species in The Bahamas.”

Credits: BMMRO / Diane Claridge; BBC; Jake Leveneson (video); Wiki (range maps)