NASSAU GROUPER: ENDANGERED… AND PROTECTED


Nassau Grouper (Melinda Riger / Grand Bahamas Scuba)

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.

Nassau Grouper (Melinda Riger / Grand Bahamas Scuba)

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.

Nassau Grouper (Melinda Riger / Grand Bahamas Scuba)

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.

Nassau Grouper Infographic (Royal Defence Force)

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

Nassau Grouper (Melinda Riger / Grand Bahamas Scuba)

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

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

RELATED POSTS

BLACK GROUPER

TIGER GROUPER

RED HIND

NASSAU GROUPER 1

CLEANING STATIONS

Nassau Grouper (Melinda Riger / . Grand Bahama Scuba)

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


Four-eyed Butterflyfish, Bahamas (Melinda Riger / G B Scuba)

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.

Four-eyed Butterflyfish, Bahamas (Melinda Riger / G B Scuba)

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.

Four-eyed Butterflyfish, Bahamas (Melinda Riger / G B Scuba)

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. 

Four-eyed Butterflyfish, Bahamas (Melinda Riger / G B Scuba)

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’. 

Four-eyed Butterflyfish, Bahamas (Lazlo Ilyes wiki)

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.

Four-eyed Butterflyfish, Bahamas (Melinda Riger / G B Scuba)

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


Sperm Whales, Bahamas (BMMRO)

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

Sperm Whales, Bahamas (BMMRO)

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. 

Sperm Whale, Bahamas (BMMRO)

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 DolphinsAtlantic 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


Yellowtail Damselfish (©Melinda Riger / Grand Bahama Scuba)

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.

Yellowtail Damselfish (©Melinda Riger / Grand Bahama Scuba)

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


Blainville's Beaked Whale, Abaco (BMMRO)

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. 

Blainville's Beaked Whale, Abaco (BMMRO)

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.

Blainville's Beaked Whale, Abaco (BMMRO)

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.

Blainville's Beaked Whale, Abaco (BMMRO)

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 Whale male, Abaco (Keith Salvesen)

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.

Blainville's Beaked Whale, Abaco (BMMRO)

All photos BMMRO except the tusked male, Keith Salvesen

AN ‘EXHILARATION’ OF ABACO DOLPHINS


Bottlenose Dolphins, Abaco Bahamas (BMMRO)

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.

Bottlenose Dolphins, Abaco Bahamas (BMMRO)

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. 

Bottlenose Dolphins, Abaco Bahamas (BMMRO)

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.

Bottlenose Dolphins, Abaco Bahamas (BMMRO)

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…

Rocky the Dolphin Tt15, from BMMRO ID photo archive

** 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

EYES ON STALKS: CONCH WATCH ON ABACO


Conch Man-o-War Cay, Abaco, Bahamas (Charmaine Albury)

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).

Conch and their eyes, Bahamas (Melinda Riger)Conch and their eyes, Bahamas (Melinda Riger)

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

Conch and their eyes, Bahamas (Melinda Riger)Conch and their eyes, Bahamas (Melinda Riger)

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