MANATEES IN THE BAHAMAS? WE GOTTEM!

February 15, 2018 by Rolling Harbour

MANATEES IN THE BAHAMAS? WE GOTTEM!

Not so long ago, most people had no idea that the waters of the Bahamas in general – and Abaco in particular – contained a small population of these curious, gentle, trusting creatures. When I first wrote about them and their adventures, there was surprise – maybe disbelief. A few years later, all that has changed thanks to the BMMRO and an outreach program that raised awareness – and consequently the sighting and reporting – of manatees. They are now widely recognised as they nose their way round harbours, docks and landing stages – and quite rightly they still excite delight and a degree of wonderment.

You can find out more – lots more – about Bahamas manatees on my page HERE. I have a post in progress about recent manatee developments with a rescue one but alas I have found I have already run out of week through some kind of bizarre time / space continuum dislocation (specifically, flagrant time-mismanagement). So I am posting a few adorable images to be going on with.

And remember, if you happen to see one, please do report it to the BMMRO or let me know. Useful data includes date, location and a description if possible of any damage – notches and nicks – to the paddle (= tail). It’s a good method for ID. Photos a bonus. Every sighting adds to the database of knowledge about these strangest of creatures of the Bahamian seas. And you’ll be pleased to know that they are undoubtedly managing to breed in the Bahamas: there are baby manatees to prove it…

All photos: BMMRO

BAHAMAS REEF FISH (43): CUBERA SNAPPER

February 8, 2018 by Rolling Harbour

BAHAMAS REEF FISH (43): CUBERA SNAPPER

The cubera snapper (Lutjanus cyanopterus) is the largest snapper species. Adults may grow to 5′ long but they average around 3′ long and weigh 40 lbs or so (the record apparently stands at a massive 126 lbs). These are game fish, and they are a commercially important species. They are also IUCN listed as vulnerable, perhaps for that very reason.

10 CUBERA SNAPPER SNAPPY FACTS

The largest of a large number of snapper species in the western Atlantic
Feed on fish, shrimps & crabs, with large strong teeth (see pics) and jaws
Among their (few) predators are sharks, barracuda, and moray eels
Edible, but beware of the danger of CIGUATERA poisoning
In summer months, spawning is governed by lunar cycles
Cuberas form huge spawning masses (to 10k) in offshore shallows
Sadly the resulting eggs and larvae are rich pickings for predators…
Youngsters live in sea grass or mangroves for protection
Cuberas are game fish with commercial importance
IUCN listed as vulnerable – largely courtesy of mankind (see »)

RANGE FINDER

CONSERVATION MATTERS

Overfishing is one of the greatest threats to the species. Those young fish that are not predated naturally and grow to adulthood are targets for fishermen. There’s no prissy ‘catch & release’, as with bonefish. At spawning time, as the fish instinctively (and predictably) mass as the moon dictates, so do the human predators. The spawning sites are where the best protection can be given, to ensure the annual reproductive cycle is uninterrupted. If not, ‘vulnerable’ will soon give way to ‘endangered’…

I’d been going to pull apart a long recipe for the “wonderfully sweet white meat ” of this fish for the tastiest morsels of info, then (not being a cook) I quickly tired of the idea. Sorry to disappoint.

Credits: Melinda Riger for the wonderful photos; range map from wiki; magpie research pickings, including (but not limited to ) Nat Geo

COOKIECUTTER SHARKS: BEASTLY LITTLE SUCKERS

February 5, 2018 by Rolling Harbour

COOKIECUTTER SHARKS

BEASTLY LITTLE SUCKERS

The Cookiecutter shark Isistius brasiliensis (aka the less scary, more genial sounding ‘cigar shark’), might be an ideal candidate for a Room 101 nemesis.** These little beasts – a species of dogfish shark – are found in several mainly island-based areas dotted around the globe, including in Abaco waters.

HOW COME THE NAME?

These sharky little b@st@rds (*technical term*) attack marine mammals and fishes, gouging out perfect round plugs of skin and flesh, leaving what are sometimes called ‘crater wounds’. Then they eat them. Imagine getting hold of a really sharp domestic cookie cutter with circular rows of razor-sharp teeth, and grinding it hard into your thigh. There! That!

The size of an adult shark:16″ max

The term ‘cookiecutter’ is also a pejorative slang term, meaning mass-produced, lacking in originality, or boringly samey, as in cookiecutter cars or TV genres etc. The little critters under consideration here are anything but…

HORRIFYING COOKIECUTTER FACTS

Live in the depths, rise vertically in the day & dive back down at dusk
Undersides have light-emitting ‘photophores’ which emphasise…
…the dark collar which acts as a lure, resembling a small innocent fish
Bioluminescence lures prey & confuses predators (more on this below)
The glow is so strong it may last for some time after removal from water

Their lips are ‘suctorial’ = they attach tightly to their target
The jaws then gouge out the victim’s flesh in a remarkably neat circle
Omni-vicious: any medium to large ocean creature is vulnerable to attack
There are even occasional reports of humans being targeted

Here are two Blainville’s beaked whales that I photographed from the BMMRO research vessel. The top whale has a number of circular healed attack marks and a recent one. You can see how deep the gouged hole is. The other has well-healed scars.

Multi-toothed: top rows of small teeth, rows of larger teeth on the bottom
The lower teeth are the cutters, acting like a saw when locked on
See header image and below for full details

HOW EXACTLY DO THEY DO WHAT THEY DO?

I can explain it no better than the renowned authority Prof. W. K. P. Dear: “the suctorial lips ensure a tight seal. It then bites, using its narrow upper teeth as anchors while its razor sharp lower teeth slices into the prey. Finally, the shark twists and rotates its body to complete a circular cut, quite possibly aided by the initial forward momentum and subsequent struggles of its prey. The action of the lower teeth may also be assisted by back-and-forth vibrations of the jaw, a mechanism akin to that of an electric carving knife”.

ARE THESE SHARKS ‘PARASITES’, WOULD YOU SAY?

The behaviour of these sharks is an example of a symbiotic relationship between two species that is parasitic. This means essentially that one gains and the other suffers (e.g. no-see-ums!). This is distinct from commensalistic symbiosis, where one species gains and the other is unaffected (e.g. cattle egrets with cattle); and mutualistic symbiosis, where both gain (e.g. cleaner fish & groupers). So, in a word, yes.

An ‘ambush predator’: they ‘hover’ in the water column waiting…
They are capable of rapid movement to catch up & latch onto prey
They will eat a passing small fish, crustacean or even squid as a snack
Sometimes they operate in schools; there is safety in numbers
The schools are thought to increase the ‘lure’ effect of the dark collar

A beached whale that’s been heavily targeted

FUN FACT TO COUNTERACT THE BAD STUFF

In the late c20, more than 30 U.S. Navy submarines were forced back to base to repair damage caused by cookiecutter shark bites, either to the neoprene footings of sonar domes or to rubber-sheathed cables. The problems were solved by using fibreglass. Oceanographic equipment and telecommunications cables are also recorded as being damaged by these sharks.

Cookiecutter Shark – the real deal

MONSTERS OF THE DEEP

These great cards from the weirdly spelled WIERD ‘N’ WILD CREATURES provide excellent factual info. Their CCS card is no exception. You’ll find more details here about the effect of the bioluminescence and so on, written as clearly as I might hope to.

** “The worst thing in the world varies from individual to individual. It may be burial alive or death by fire, or by drowning, or by impalement, or fifty other deaths. There are cases where it is some quite trivial thing, not even fatal.” (George Orwell, 1984)

Alright now…

Credits: BMMRO – header image; beaked whale photos – Keith Salvesen / BMMRO; Te Ara NZ for the main jaw image; all small images with thanks to Wiki and respective photographers who took the time to upload them for all to enjoy & learn from; ‘wierdnwonderful creatures’ for the monster card; range map from Wiki

PS Apologies to anyone who bothered to wade through this, and stayed awake long enough to notice that formatting gremlins struck halfway through

GRAYSBY (GROUPER): BAHAMAS REEF FISH (42)

February 1, 2018 by Rolling Harbour

GRAYSBY (GROUPER): BAHAMAS REEF FISH (42)

The Graysby Cephalopholis cruentata is a small, spotty grouper, which grows to a maximum of around 16 inches. These rather unassuming and solitary fish have a preference for coral reefs, where they can blend in with their surroundings on ledges and in caves and crevices during the day. At night, they become active – that’s when they feed on feed on small fish, crabs and shrimps.

The graysby has variable colouring in a range from light brown to pale gray, with all-over spots that may be red, orange or brownish. Often, they have 3 to 5 contrasting spots on their backs, along the base of the dorsal fin, as below:

The long erectile dorsal fin comprises both spines and ‘rays’ – spines at the front, rays at the back. Like this:

The spots of a graysby can change in colour (at least to a limited extent), becoming either paler or darker. I imagine this is a protective feature to enable the fish to blend in more easily with its reef surroundings.

Graysby (grouper) - Melinda Riger / Grand Bahama Scuba

Signalling to turn right…

I wondered if they are edible. I believe so – but then I also read that the larger adults carry the risk of ciguatera and raised mercury levels. So I’ll give it a miss thanks.

Photo & other credits: all photographs by Melinda Riger / Grand Bahama Scuba; aqua.org; SAMFC (drawing)

WTF? (WHAT’S THAT FISH?) 14: ARROW CRABS

January 16, 2018 by Rolling Harbour

WTF? (WHAT’S THAT FISH?) 14: ARROW CRABS

It’s been a while since the last in the WTF? series, which is dedicated to the wilder, less conventionally fish-shaped side of reef life – those creatures that you may come across, blink into your face-mask, and silently mouth the words ‘What’s That Fish?’ (that’s what it looks like you are saying, anyway).

Let’s meet some Arrow Crabs Stenorhynchus seticornis, one of the very few creatures surely to have a triangular body plus a huge pointy nose (rostrum), supported on long skinny legs. To which add, they wear tiny blue gloves on their two front claws.

These crabs are coral reef dwellers and mostly stay concealed during the day. Their body is protected by a carapace, and the rostrum has serrated edges like a tiny rasp or file. I haven’t found a definitive reason for this gadget, but I suspect it is more for probing than for piercing or fighting.

There’s a considerable colour variation among these crabs, as these images show. The body may even have blue iridescent lines (#2, above). And those claws may be any of 50 shades of blue…

Arrow crabs are most active at night. They eat feather-duster worms (illus.) and similar invertebrates such as bristle worms.

Feather-duster worm (Melinda Riger / G B Scuba)

Arrow Crab Meal

Like certain types of shrimp, they also have a symbiotic relationship with anemones, whereby they make use of an anemone to benefit from the food it captures – and possibly for cover too. They are protected from anemone stings, whereas some of their predators are not.

This was the place where I was going to tell you about the arrow crab’s private life, but, well… “it’s complicated”. Briefly it is: male passes sperm-filled capsule to female; she uses it in some way whereby it fertilises her eggs; she then ‘broods’ the eggs in one of her ‘swimming legs’; the eggs hatch into larvae and swim off to eat plankton; each one then grows & moults, repeating the process until it has reached adult form. On balance, humans have arguably perfected a preferable method.

Arrow Crabs are apparently popular aquarium creatures, although they sound to me rather a disagreeable challenge. They can move quickly on those long legs, and it seems as if they inclined to be aggressive to other inhabitants of the tank. As far as I can make out, it’s best not to put 2 of them together: they certainly won’t be doing the sperm capsule thing described earlier…

Master of Disguise

Photo credits: Melinda Riger / G B Scuba (1, 3, 4, 5, 6); Adam Rees / Scuba Works (2, 8, 9); Nick Hopgood,Wiki (7); Chuck Elliot – video

SOUTHERN STINGRAYS: BAHAMAS REEF FISH (41)

January 9, 2018 by Rolling Harbour

SOUTHERN STINGRAYS: BAHAMAS REEF FISH (41)

Anyone who has scuba-dived or snorkelled around the bright coral reefs of the Bahamas, or hunted bonefish out on the Abaco Marls will have come across Southern Stingrays Dasyatis americana. And there are certain places (eg Manjack Cay) where you can actually feed them – and not come to any harm…

FEED THEM? AREN’T THESE GUYS LETHALLY DANGEROUS CREATURES?

The name that always comes to mind in connection with stingrays is poor Steve Irwin, the charismatic Australian wildlife expert who was tragically ‘stung’ over his heart as he swam close over a ray while filming underwater. But this was, it would appear, a dreadful combination of circumstances with a terrible outcome.

The ray’s stinger is in fact an erectile venomous barbed spine near the base of the tail and not on the end of it (as one might expect). But these creatures are not out to harm you – though of course when you are in their environment you should accord them the respect that they merit.

If you are walking / wading in the water, avoid the risk of accidentally treading on a ray. Best to shuffle your feet forward in the sand; if there’s a half-concealed ray feeding or resting on the bottom nearby, it will swim away peacefully. I took the photo below while bonefishing on the Marls; the ray directly ahead slowly makes off as the skiff drifts closer. The next one is of a ray with its young – completely aware of us as we glide past to one side, but not especially bothered.

If you are swimming, snorkelling or diving, don’t get too close – especially by swimming directly over a ray (apparently Steve Irwin’s mistake, so that he was struck right in the chest by the stinger when the ray reacted).

Enough of the potential dangers. The southern stingray is a magnificent creature, as Melinda’s wonderful photographs show. She spends half her life underwater and I’m not aware that she has had a problem with a ray.

Like many larger sea creatures, stingrays need help with their personal care – the removal of parasites, dead skin and so forth. And so they make use of the services offered by small fish like gobies, wrasses and shrimps at a CLEANING STATION. Here are 2 photos of rays doing just that. You can see the tiny fish by the reef, going about their work. There’s a mutual benefit in this symbiotic relationship, in which it is understood that the cleaners are unharmed. Indeed, they will often enter the mouths and gills of a fish to clean… including the teeth. So there’s dental hygiene on offer too…

RELATED POSTS

YELLOW STINGRAY

GRACE WITH ATTITUDE

TAKEN TO THE CLEANERS

Photo Credits: Melinda Riger / Grand Bahama Scuba, except for the feeding photo (cheers, Samantha Regan), the ‘specimen’ from Tomas Willems (Wiki) and my two noted above

CHRISTMAS TREE WORMS: SEASONAL SPIROBRANCHES

December 18, 2017 by Rolling Harbour

CHRISTMAS TREE WORMS: SEASONAL SPIROBRANCHES

“Deck the Reefs with Worms Like Christmas Trees… Fal-La-La-etc-etc ” is a traditional Carol familiar to all. Well, most. Ok, some, then. Oh right – maybe with different words? Anyway, now is the perfect time to take another look at these remarkable subsurface symbols of seasonal good cheer (nb they are animals not plants).

10 CHRISTMAS TREE WORM FACTS TO PONDER

The 2 colourful spirals are not the worm, but complex structures for feeding & respiration
The spirals act as specialised mouth extensions for ‘filter-feeding’
Prey is trapped by the feathery tentacles & guided by cilia (microscopic hairs) to the mouth
The tentacle things are radioles and act as gills for breathing as well as prey traps
It is not believed that prey slide down the spiral to their doom, like on a helter-skelter

Christmas Tree Worm (Melinda Riger / Grand Bahama Scuba)

The actual worm lives in a sort of segmented tube, with extremely limited mobility skills
It contains digestive, circulatory & nervous systems – and a brain in the middle of it all
The worm also has a tiny drainage tube (I think I have this right) for excretion etc
They embed themselves into heads of coral such as brain coral. And stay there
And yes, the Christmas trees are retractable… (see below for some action)

HOW DO THE WORMS… YOU KNOW… ERM… REPRODUCE?

This is a delicate area. They don’t tend to talk about it much, but as far as I can make out they eject gametes from their what-I-said-above. There are mummy and daddy worms, and their respective gametes (eggs and spermatozoa) drift in the current and presumably into each other to complete the union. The fertilised eggs develop into larvae, which settle onto coral and burrow into it, build their protective tubes and the process begins again.

YOU DON’T REALLY UNDERSTAND THESE CREATURES, DO YOU?

I won’t lie. I found it hard to work out how the CTWs function in practice. There are plenty of resources showing them in their full glory, but that only takes one so far. Then I came across a short video that shows it all brilliantly simply (except for the reproduction part).

The worms, in their coral burrows, hoist their pairs of ‘trees’. You can easily see small particles – possibly zooplankton – drifting in the water, and the radioles swaying to catch potential food. Suddenly it all makes sense (except the repro bit – I haven’t found footage of that). Next: the New Year Worm (there is no Easter worm).

A WHOLE FESTIVAL OF CHRISTMAS TREE WORMS

Credits: Melinda Riger (G B Scuba); Nick Hobgood; Betty Wills; Video by ‘Super Sea Monkey’;Reef Collage by RH; MarineBio; Wikibits & Magpie Pickings

Happy Christmas to all those who put up with RH with such fortitude

NASSAU GROUPER: ENDANGERED… AND PROTECTED

December 7, 2017 by Rolling Harbour

NASSAU GROUPER: ENDANGERED… AND PROTECTED

Most creatures need some space for creative activity of one sort or another. Especially one particular sort, namely breeding. And for vulnerable and endangered species, this is especially important in order to maintain a sustainable population, and preferably to increase it year on year. Which is why there are closed seasons for certain fish, ensuring a time when they can be left alone to breed in peace and to perpetuate their species.

The Nassau grouper Epinephelus striatus is just one of a number of grouper species that inhabit Bahamian waters. They are mostly found in the Northern Bahamas but only the Nassau grouper is on the IUCN Red List as an Endangered Species in need of protection.

WHY ARE THESE FINE FISH ENDANGERED?

Sad to say, mankind is the main cause of the population fragility that has led to the official listing, and the imposition of a strict closed season for 3 months between December 1st and February 28th. Scientific studies have shown that commercial overfishing has reduced a thriving population to fewer than 10,000 mature fish. That may sound plenty to be going on with… until you consider that a net annual loss of only 10% would lead to extinction in a decade.

10 CONVENIENTLY COLLECTED NASSAU GROUPER FACTS TO PONDER

An adult can grow to more than a metre long, and weigh 25 kg
They tend to be solitary daytime feeders, eating small fish & crustaceans
Their large mouths are use to ‘inhale’ or suck in prey
The colouring of an individual can vary from red to brown
These fish have little black spots around the eyes (I’ve no idea why).
Their habitat is in the vicinity of coral reefs, from shallows to 100 m deep
Spawning occurs in Dec & Jan during a full moon
Large numbers gather in a single location to mate in a mass spawning
These groupers are slow breeders, which compounds the overfishing problem
They are easy mass targets at spawning time; hence the need for a closed season

Department of Fisheries information sheet (interesting if you have the time)

A Nassau Grouper glumly contemplates the possibility of extinction Nassau Grouper (Melinda Riger / Grand Bahamas Scuba)

RELATED POSTS

Credits: all photos, Melinda Riger; Infographic by Royal Defence Force (tip o’ the hat to Char Albury); Info Sheet, Dept of Fisheries

BAHAMAS REEF FISH (40): FOUR-EYED BUTTERFLYFISH

December 1, 2017 by Rolling Harbour

BAHAMAS REEF FISH (40): FOUR-EYED BUTTERFLYFISH

Four-eyed (or foureye) butterflyfish (Chaetodon capistratus) are small, somewhat circular fish with an endearingly pointy little snout. They are one of several butterflyfish species found in Bahamian waters. On their sides are smart ‘go-faster’ chevrons, with the unmistakeable white-circled black ‘eye’ at the back. The real eyes, in the conventional position, are small and far less noticeable, not least because of the stripe that passes right through them.

WHY THIS EXOTIC PATTERNING?

This type of misleading pattern is not uncommon in fishes and indeed in terrestrial creatures. It creates confusion in predators – and when this little fish is threatened it swims away with its large ‘eye’ prominent to the pursuer. It acts as a warning and an off-putting feature that suggests ‘don’t eat me’. If you half-close your eyes and look at the image below, the large eyes stand out against the reef background and hint at a creature not to be tangled with. Why reef predators don’t rumble this ruse within minutes, I have no idea.

WHAT IF THE RUSE FAILS?

Foureyes are very agile swimmers and can take advantage of narrow gaps and clefts in the reef by swimming sideways or even upside-down to manoeuvre away from danger and to safety where the predator cannot reach it.

AND IF THAT DOESN’T WORK?

If the foureye is in deep trouble, it has an alternative cunning plan. It will turn and face the pursuer, head down and dorsal spines erect. This posture says both ‘I’m very spiny – watch out’ and ‘I’m coming atcher’.

AND IF THAT DOESN’T WORK? I’M WORRIED FOR IT NOW…

Curtains. It’s lunchtime, I’m afraid.

♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦

Foureyes are far from the only reef dwellers that have predator-confusing markings. In the image below, the foureye at the top is swimming with a larger BUTTER HAMLET, a species that also relies on an abnormal spot pattern to put off predators. This is a great capture, and it also illustrates how the smaller reef fishes can hang out together amicably.

RELATED POSTS

REEF BUTTERFLYFISH

SPOTFIN BUTTERFLYFISH

LONGSNOUT BUTTERFLYFISH

Image Credits: 1, 2, 3, 4, 6, Melinda Riger / Grand Bahama Scuba; 5, Lazlo Ilyes

SPERM WHALES – BMMRO FIELD TRIP, BAHAMAS

November 28, 2017 by Rolling Harbour

SPERM WHALES – BMMRO FIELD TRIP, BAHAMAS

I can never quite get my head around the fact that the waters around Abaco are home to the twin leviathans, sperm whales and humpback whales. And before anyone points it out, I realise they can’t actually be twins: sperms whales (cachelots) are TOOTHED WHALES whereas humpback whales are BALEEN WHALES.

During November, the Bahamas Marine Mammal Research Organisation (BMMRO) undertook a rather special field trip. Using sophisticated devices, the scientists first located a group of sperm whales, and then tracked them through the night using the communications between the creatures – ‘vocalisations’ – to follow them. Later analysis of the recordings will have made it possible to identify the individuals through their unique vocal patterns – and so to recognise them again.

The hydrophonic equipment used is extremely sensitive, and can pick up the sounds made by whales and dolphins over a great distance. The box of tricks looks deceptively modest – I took these photos on a previous trip when we were looking for beaked whales and dolphins. Charlotte Dunn holds the microphone submerged on a cable and underwater sounds are amplified so that the slightest chirrup of a dolphin can be heard by everyone on the vessel. The sounds are recorded and locations carefully logged.

Besides the sperm whales, the BMMRO team also had sightings of spotted dolphins, bottlenose dolphins and beaked whales during the field trip. These bonus sightings will also have been logged for future reference. It all adds to the detailed research data that assists the conservation of the prolific marine mammal life in Bahamian waters.

Atlantic Spotted Dolphins Atlantic Spotted Dolphins, Bahamas (BMMRO)

By the time one of the whales decided to breach, it was some distance away, so I’m afraid I can’t bring you a dramatic close-up from the trip. But just to see this view at all is breathtaking.

All photos BMMRO except the 2 hydrophone ones on the research boat (Keith Salvesen)

BAHAMAS REEF FISH (39): YELLOWTAIL DAMSELFISH

October 23, 2017 by Rolling Harbour

BAHAMAS REEF FISH (39): YELLOWTAIL DAMSELFISH

Yellowtails are just one of several damselfish species in Bahamas waters. These small fish are conspicuous not just for the bright tails that give them their name. More striking if anything – especially if seen underwater in sunlight against the coral – are the electric blue spots visible in both adults and juveniles.

The body of adults is dark blue to brownish to almost black

The body of juveniles is blue

Yellowtails are a common and widespread variety of damselfish. They have a limited ability to change colour according to their surroundings, but with their bright tails and luminous blue flecks, it’s hard to see how they can look, to a predator, anything other than a tasty snack.

I have enjoyed seeing these little fish at Fowl Cay Marine Preserve, Abaco. The reef there makes for easy and rewarding snorkelling, with a wide variety of small and medium-size reef fishes to be seen. It’s an expedition I would definitely recommend to anyone wanting to see a healthy and active reef in a completely natural protected area.

I found that a video I took with a tiny camera was sadly of use only to myself. No one else would be able to make anything out due to the marked camera shake. Novices, huh? You are spared that: here’s a brief example of yellowtails swimming instead, showing the difference between juveniles and adults.

Credits: all photos, Melinda Riger / Grand Bahama Scuba; video from Desert Diving

BLAINVILLE’S BEAKED WHALES IN ABACO WATERS

October 16, 2017 by Rolling Harbour

BLAINVILLE’S BEAKED WHALES IN ABACO WATERS

It’s hard to believe that the seas around Abaco and its cays are home to a number of whale species, from huge sperm and humpback whales down to so-called dwarf or pygmy species. In the middle of this range come the beaked whales, the most common being the Blainville’s Beaked Whale. I say ‘most common’, but in fact they are rare in the world, being found in only two other main locations on earth.

These whales are carefully monitored by the Bahamas Marine Mammal Research Organisation (BMMRO), and there is a tagging program to keep track of them. As with dolphins, individuals are identified by markings on the dorsal fin, which vary for each whale. The one above has distinctive scarring at the tip. There are also striations on the body, and conspicuous circular marks that are healed wounds caused by cookie-cutter sharks.

To the untrained eye, there are no noticeable marks on the dorsal fin of the whale above. However, the whale’s back has a prominent pattern of scarring and healed cookie-cutter wounds. The whale below really looks as though it has been in the wars, with long deep healed wounds behind the head.

I can’t tell without seeing the head, but I wonder if it is a male and the scars have been caused in a fight with another male – adult males have prominent tusks with which they do battle. Here is an photo that I took from the research boat on a different occasion. The tusks protrude upwards from the lower jaw, and are often covered in barnacles. They are capable of causing serious injury.

Blainville’s beaked whales are amongst the deepest divers of all whales. But that and other whale topics will have to wait for another day… My computer malware / virus has been removed professionally with no data loss, and I have some catching up to do. Cost in terms of panic and stress: huge. Cost in real terms: $90.

All photos BMMRO except the tusked male, Keith Salvesen

‘RAISE AWARENESS’: SPOTTED EAGLE RAYS

October 10, 2017 by Rolling Harbour

Spotted Eagle Rays – Abaco, Bahamas

‘RAISE AWARENESS’: SPOTTED EAGLE RAYS

Mention of rays may conjure up thoughts of the familiar southern stingrays that populate the bright shallows and colourful reefs of the Bahamas. But there are other ray species out there gracefully patrolling the coral reefs – and one of these species is the spotted eagle ray (Aetobatus narinari).

These fish (for that is what they are) are not uncommon. In fact they are found in tropical oceans worldwide (though there is a taxonomic distinction between the Atlantic version and the Pacific / Indo-Pacific ones). Note the concentration in the Caribbean sea.

Spotted eagle rays obviously have spots, but they are not notably eagle-like to look at. In fact, their snouts resemble a duck’s bill, and in some place they are less glamorously known as the duckbill ray. The ‘eagle’ part relates to the way in which they use their wings and appear to be soaring as they glide effortlessly through the water (see videos below).

Despite their global presence, these rays are categorised as ‘near-threatened’ on the IUCN Red List. Aside from vulnerability to predators including many types of shark, the rays may be caught as bycatch. In some areas they suffer entanglement in shark nets. And unsurprisingly there is a trade for them for large commercial aquariums. For the Atlantic species, Florida has taken a lead by banning fishing for, landing, buying or trading in spotted eagle rays.

10 ESSENTIAL FACTS ABOUT SPOTTED EAGLE RAYS

They have 2 – 6 venomous barbed spines at the base of the tail
Adults are among the largest rays, with a 10 ft wingspan
They can leap clear of the water, and may do this more than once at a time
Occasionally they land in boats, to the consternation of all concerned
Their main diet is small fish and crustaceans, & sometimes octopuses
Their broad snouts are used to dig food out of the seabed as they forage
The rays are basically shy but may be curious of divers & snorkellers
They suffer from parasites, both externally and in their gills
Ray sex is quite physical, yet actual mating is brief (up to 90 secs…)
The female hatches her eggs internally, then her ‘pups’ are born live a year later

SPOTTED EAGLE RAY PUP

VIDEO SHOWCASE

These 3 short videos demonstrate the grace and beauty of spotted eagle rays as they glide elegantly around the reefs. The first (50s) was taken off Grand Bahama by Fred Riger (Melinda’s husband, for those who follow the underwater forays hereabouts); then one by Stephen Dickey (2:12) ; and finally one from Wildscreen Arkive (2:00).

WEIRD CREATURE CORNER

I have a lot of time for these cards produced by ‘Weird ‘n’ Wild Creatures’. In their unique style they are simple, educative and often give information nuggets not found elsewhere. The link is to their 4th series, Monsters of the Deep.

Photo credits: Gabrielle Manni (1), (5); Catherine & Tara Pyfrom (2); Melinda Riger / Grand Bahama Scuba (3); Lazlo-photos Wiki (4); Wiki (baby ray thumbnails); John Norton Wiki (6); Jacob Robertson Wiki (7); Weird ‘n’ Wild Creatures – card images. Videos as credited in text.

Spotted Eagle Ray, TCI (Jacob Robertson, Wiki)

HAWKSBILL TURTLES: DIVERS VIEWS…

October 2, 2017 by Rolling Harbour

HAWKSBILL TURTLES: DIVERS VIEWS…

Daydream for a moment. Imagine that you had a different occupation. And your new one involved daily contact with spectacular wildlife underwater (this assumes you can swim – debatable in my case). And access to some upmarket camera equipment. And the ability to use it effectively. Oh, and use of a reliable boat. And some sea.

Say, for example, you joined a dive operation. Then the chances are very high that these wonderful creatures would be a part of your daily 9-to-5.

You wake up with a start. Oh no! Half an hour gone, and that crucial email still half-written… Where did the time go?

All gorgeous turtles taken by Adam Rees of Scuba Works (slogan: “Land is so overrated”) in the course of his everyday working life. Some people, eh?

AN ‘EXHILARATION’ OF ABACO DOLPHINS

September 25, 2017 by Rolling Harbour

AN ‘EXHILARATION’ OF ABACO DOLPHINS

Bottlenose dolphins! Tursiops truncatus! These engagingly playful show-offs of the inshore waters round Abaco are 99.99% adorable**. It’s been a harrowing few weeks in the western Atlantic, and everyone is hoping that the 2017 hurricane season has had enough of causing death and destruction over vast swathes of vulnerable islands and on the US mainland. Some cheer is needed.

Dolphins are good for the soul. And if you are out on a boat watching them – and especially tracking them for a whole day – every encounter reinforces the impression that all the leaping, bow-wave riding, boat under-swimming, and general sociability and interaction is often as much for sheer enjoyment as anything else.

Abaco is fortunate in having the HQ of the Bahamas Mammals Research Organisation (BMMRO) based at Sandy Point. That just happens to be an excellent area for bottlenose dolphin spotting in the turquoise shallows. Many sightings are made within clear sight of land. Further south, where the bright blue gives way to darker and deeper water, live the equally frolicsome Atlantic spotted dolphins. The 3 photos above were all taken on the margins of where the colour of the sea changes from light to dark.

I’m a bit of a collector of collective nouns. For dolphins, apart from the matter-of-fact ‘group’ or ‘pod’, there is no exotic word to describe a number of them when they are having fun. No equivalent of ‘exaltation’ (larks), ‘charm’ (goldfinches) or ‘parliament’ (owls). So I’m nominating an ‘exhilaration’ as a candidate to fill the gap…

The photo above shows clearly how individual dolphins can be identified by researchers. All tend to have scars or tears to their dorsal fins that enable them to be distinguished. The closest has distinctive scars near the tip. The furthest has a W-shaped nick at the back. In fact, it could even be Rocky, a well-known dolphin on Abaco that has been sighted over many years. There are regular reports annually. I saw him myself once, in 2012, playing about in Hopetown harbour.

STOP PRESS To demonstrate how the ID methods work, I’ve now cross-checked with the BMMRO photo ID archive. Here is Rocky’s original dorsal fin ID image (“Tt15”) from October 2010. There’s a W-shaped nick, sure, but my speculation above was wrong because overall the two fins are clearly different…

** The 0.01%? Dolphins may, rarely, be alarming for divers in circumstances I won’t repeat here (hint: to do with over-friendliness, ok? Yes, the thing that dogs do)

Credits: all photos BMMRO – and taken in the last 2 months

QUEEN TRIGGERFISH AND GOOD RIDDANCE TO MARIA

September 22, 2017 by Rolling Harbour

QUEEN TRIGGERFISH AND GOOD RIDDANCE TO MARIA

I can think of no sensible connection between the colourful yet undoubtedly strange and grumpy-looking looking queen triggerfish Balistes vetula, and a hurricane. However, Hurricanes Irma and Maria have been rightly dominating the news and everyone’s thoughts for nearly 3 weeks now. And most of the recent posts from Rolling Harbour, for that matter. It’s not been a great time for looking at the birds, beasts and fishes. So, as Maria drifts eastwards and away from the Bahamas into the open ocean, it’s time for a splash of colour – and a fish I have not featured before.

Hurricane Maria tracking at 11.00 EST on Sept 22

The queen triggerfish, sometimes known as an Old Wife, is an Atlantic reef fish. This species is sometime fished for as game, and I know that a few have been taken from off the rocks at the south end of Delphi beach over the years – though perhaps not exactly on purpose.

This fish typically is coloured with shades of blue, purple, turquoise and green with a yellowish throat, with pale blue lines fins on head and fins. It’s minor superpower is to be able to change its coloration to some extent to match its reef surroundings and assist camouflage. Its favourite food is the sea urchin.

Let’s hope this is the last post to feature anything about hurricanes for a good long time, as we think of all those still struggling to make sense of the terrible destruction they have recently experienced – in some places, twice over.

Credits: Melinda Riger / Grand Bahama Scuba; Mark Peter, Wiki; Clark Anderson / Aqua-images

CLEANING UP IN THE BAHAMAS: PEDERSON SHRIMPS

August 29, 2017 by Rolling Harbour

CLEANING UP IN THE BAHAMAS: PEDERSON SHRIMPS

Pederson’s Shrimps Ancylomenes pedersoni (also known locally as Peterson’s shrimps), are one of several species of cleaner shrimp found in The Bahamas and more generally in the Caribbean seas. The species was named in 1958 by a multifaceted medico-oceanologist-zoologist Fenner A. Chace. He seems to have specialised in shrimps, finding distinct and differing species and naming them (not unreasonably) after himself (chacei);or colleagues and people he knew / admired; and in one case his wife. Mr Pederson was among them.

This tiny transparent creature with its vivid blue / purple markings and straggling pale antennae is unmistakeable, and helpfully cannot be confused with any other locally found shrimp species. Here’s an idea of its size, compared with a human finger and a blue parrotfish.

WHERE DO THESE SHRIMPS LIVE?

Their preferred home is… and it’s certainly a left field choice among sea creatures… in amongst the stinging tentacles of certain sea anemones. Not only do they not get stung, but of course they are well-protected by the defensive pain that their hosts can inflict. They are usually found singly or in pairs, but sometimes a whole colony may inhabit the same anemone.

SO EXPLAIN HOW THEY DON’T GET STUNG

Ok. The shrimps gradually build up a kind of resistance by pressing their bodies and antennae against the tentacles of the host anemone for increasing lengths of time, until they become immune. It’s like one of those kids’ electric buzzer / rheostat machines. Or a TENS machine (for those who know about backache).

IS THERE A DOWNSIDE TO ALL THIS?

Yes indeed. If a shrimp moves away from its host for a few days, it has to start the process of immunisation all over again. So presumably they tend to stay home-lovin’.

Home sweet home for the Pederson shrimps Pederson's Cleaning Shrimp, Bahamas (Melinda Riger, GB Scuba)

SOMETHING ABOUT THE CLEANING, PLEASE

These shrimps offer ‘cleaning services’ to passing fish. When on duty, as it were, they wave their antennae vigorously to attract attention. A fish being cleaned will remain stationary and passive while external parasites and dead skin are removed. Many fish will open their mouths and gill covers for internal cleaning, with the tacit agreement that the cleaner will not become a snack. Shrimps often work in conjunction with small cleaner fish such as some species of goby and wrasse – see the links below for more on this topic, with copious images…

CLEANING STATIONS

CLEANER FISH

Credits: all photos by Melinda Riger / Grand Bahama Scuba

BAHAMAS REEF FISH (38): SPOTFIN BUTTERFLYFISH

August 22, 2017 by Rolling Harbour

BAHAMAS REEF FISH (38): SPOTFIN BUTTERFLYFISH

Butterflyfishes are a large family of mainly colourful small fish somewhat like mini-angelfish. The spotfin butterflyfish (Chaetodon ocellatus) is one of several types of butterflyfish found in the western Atlantic Ocean; and one of half a dozen or so you are likely to see nosing around the coral reefs of the Bahamas.

The name ‘spotfin’ derives from the dark spot on the dorsal fin. At the front end, there is a distinctive black vertical stripe that passes right through the eye. Combined with the vivid colouring, predators are in theory confused or warned off. The spotfin’s superpower (on a modest scale) is that at night, a change of appearance occurs in adults. The dark patch on the dorsal fin increases in size, and dark bands appear on the body. This seems to be in order to provide further protection during the darker hours.

The spotfin above has an isopod attached to it, a type of crustacean with a segmented body. Primitive fossils of these creatures have been dated back some 3m years. Want to know want this one is up to? These things “are mostly external parasites of fish or crustaceans and feed on blood, having piercing and sucking mouthparts and clawed limbs adapted for clinging onto their hosts”.

Soldierfish photobombs a spotfin. Or maybe it’s vice versa?

Reading about this particular species of butterfly fish, I discovered that the spotfin “is very common and very hard to maintain in a tank” – as if the two facts are somehow connected. So might they be coarse or vulgar, and thus unsuitable companions for better bred and perhaps sensitive aquarium fish? As it turns out, it may be because they are vulnerable to predation, and so can coexist only with peaceable tank friends.

Spotfins are perfectly happy swimming upside down; and their party trick apparently is to rise to the surface and squirt a jet of water in the air. Sadly, I couldn’t come up with a photo of this…

LONGSNOUT BUTTERFLYFISH

REEF BUTTERFLYFISH

Credits: All fab photos by Melinda Riger / Grand Bahamas Scuba

EYES ON STALKS: CONCH WATCH ON ABACO

August 10, 2017 by Rolling Harbour

EYES ON STALKS: CONCH WATCH ON ABACO

This is not so much about you looking at, and admiring (without salivating too much, I trust) conchs in their natural element. More about them watching you watching them – and focusing on their rather remarkable stalk-based eyes. Take a look at these examples of the ‘watcher in the shallows‘ (to misquote a well-known book title).

HALF A DOZEN CONCH EYE FACTS TO PONDER

The eyestalks are attached to an extendable ‘snout’
The two eyestalks (ommatophores) are retractable within the shell
Their purpose is to provide a wider field of vision around the shell
The eyes at the tip of each eyestalk have ‘proper’ lenses, pupils and irises
Amazingly, amputated eyes normally regenerate completely
The small projection below the eye is a ‘sensory tentacle’ or feeler

CAUTIONARY WARNING

For a rather depressing view of the current state of conch populations, check out this recent article in the MIAMI HERALD. Not a great deal to be optimistic about…

I’M WATCHING YOU…

CREDITS: All remarkable ‘conch watching’ photos by Melinda Riger / Grand Bahama Scuba – except for the wonderful header image by Charmaine Albury (contributor the The Birds of Abaco), taken on Man-o-War Cay; Cindy James Pinder for the heads-up for the Miami Herald article

DOLPHINS DISPORTING IN THE BAHAMAS

August 3, 2017 by Rolling Harbour

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.

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.

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.

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.

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

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 not Bottlenose 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!)