ENDANGERED SPECIES, ABACO (3): NASSAU GROUPER


Nassau Grouper (Melinda Riger / G B Scuba)

ENDANGERED SPECIES, ABACO (3): NASSAU GROUPER

The Nassau grouper Epinephelus striatus is one of a number of grouper species found in Bahamian waters. Of these, only the Nassau grouper is on the IUCN Red List, as Critically Endangered. When I last wrote about them they were in the lesser category ‘Threatened’.

Nassau Grouper (Melinda Riger / G B Scuba

In order to sustain a viable population, it is vital to maintain numbers and preferably to increase them year on year. Once it became clear that year-round commercial overfishing was a prime component of the steep decline in the population, a 3-month closed season during the breeding period was imposed. This has ensured that at the most critical time in the lifecycle of the species, the groupers are left alone to breed in peace and to perpetuate their species.

Nassau Grouper (Melinda Riger / G B Scuba)

The closed season operates from December to February to maximise the chances of breeding success. As with some other fish species, reproduction occurs around the full moon. The fish gather at spawning sites and the process is at its height around sunset.

Nassau Grouper (Melinda Rogers / Dive Abaco)

10 CONVENIENTLY COLLECTED NASSAU GROUPER FACTS

  • 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 mainly 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 / G B Scuba)

A Nassau Grouper glumly contemplates the possibility of extinctionNassau Grouper (Melinda Riger / G B Scuba)

RELATED POSTS

BLACK GROUPER

TIGER GROUPER

RED HIND

CLEANING STATIONS

Nassau Grouper (Melinda Rogers / Dive Abaco)

Credits: Melinda Riger / Grand Bahamas Scuba (1, 2, 3, 5, 6); Melinda Rogers / Dive Abaco (4, 7)

CORAL SUNSHINE: PICTURE PERFECT ABACO (9)


CORAL SUNSHINE: PICTURE PERFECT ABACO (9)

coral-in-sunlight-melinda-rogers-dive-abaco

Off the east coast of Abaco lies one of the longest barrier reefs in the world. Some authorities suggest it is the third longest, but the exact ranking of the top dozen coral barriers is a matter for considerable debate. None of the lists I have just checked agree, except that the Great Barrier Reef is the outright winner. I suspect that the problem lies in the loosely generalised description of ‘barrier reef’ and in variations of the appropriate criteria for determining length (it may also depend on who is doing the measuring, of course).

Melinda Rogers of Dive Abaco took this bright sunlit ‘Coralscape’ in the Fowl Cays National Park. It’s a place I have tentatively snorkelled around with great pleasure, despite being in the top dozen most useless swimmers in the world (my appalling underwater videos were disqualified from the rankings for being… rank).

GROUPER AT THE CLEANERS: PICTURE PERFECT BAHAMAS (5)


GROUPER AT A CLEANING STATION: PICTURE PERFECT BAHAMAS (5)

BLACK GROUPER AT A CLEANING STATION (Melinda Riger @ G B Scuba)

This black grouper (‘Arnold’) is at a so-called CLEANING STATION, being groomed by gobies. The process is an example of species symbiosis known as MUTUALISM. This is a transaction between individuals of two species that is mutually beneficial. Here, the primary creature pauses at a locally familiar cleaning station and allows itself to be expertly cleaned by tiny fishes such as gobies and wrasses to remove parasites, dead skin and so forth. This nurture even includes, as here, inside the mouth and gills. The gobies benefit by feeding on the proceeds of their endeavours removed from the host (or ‘client’ as one might say). And of course, in return for their favours a collateral benefit is that they can feed freely without being eaten by a potential predator. 

Credit: Melinda Riger / Grand Bahama Scuba

CORAL REEFS AND HURRICANE DAMAGE ON ABACO BAHAMAS


Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)

CORAL REEFS AND HURRICANE DAMAGE ON ABACO BAHAMAS

The spectacular coral reef chains of the Bahamas include the 3rd largest barrier reef in the world. Abaco’s reef system stretches from Little Harbour to beyond the northern end of the mainland, as Sandy Estabrook’s map shows. Inside the reef: the Sea of Abaco. Beyond the reef and the next landfall east: Western Sahara, south of the Canary Islands.Abaco Map Sandy Estabrook
A rainbow effect of filtered sunlight on sea fansReef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)
Since the devastation of Abaco by Hurricane Dorian last September, a number of surveys have been carried out. Some of these relate to the impact of the storm on the natural world – the damaged forest and coppice, the bird-life including the Abaco specialities, and the marine life including marine mammals, fish, and reef structures and environments.
Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)
A recent assessment by the Perry Institute for Marine Sciences (PIMS) in Abaco and Grand Bahama waters has been carried out on the coral reefs to determine the extent to which the vulnerable structure, ecology and environment has been damaged. Some details have just been published in the Nassau Guardian in an article by Paige McCartney. The LINK is below.
Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)
DAMAGE FINDINGS IN BRIEF
  • 25 – 30% of the 29 reef sites surveyed are devastated
  • factors include damage from debris, silt burial, and bleaching
  • uprooted casuarina trees were caught in the storm surge, causing damage
  • in particular, corals have been smashed and reef structure destroyed
  • there is biomass loss – basically reduced populations of fish & other organisms

Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)

RAYS OF LIGHT
Although the reef systems of both islands have been significantly damaged, in other areas little damage was found. Moreover, in some areas the storm had washed away some types of seaweed that are harmful to the reefs. The hope is that restoration of the damaged areas can be achieved with careful management.
Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)
WHAT CAN BE DONE NOW?
Action towards restoration and future protection includes:
  • removal of debris and other deleterious matter (eg silt)
  • cutting back the non-native, invasive casuarinas from the shoreline
  • restoration programs (recent successes with ‘coral farming’ could be vital)
  • extending marine protected areas
  • developing a rapid response protocol to meet extreme situations

Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)

The reports ends with some welcome news: Government departments have recently proposed putting $5 million towards a coral restoration project on Abaco, including the establishment of a and-based aquaculture facility to support coral growth in nurseries. Let’s hope that becomes a reality.

The publication of the PIMS report and its findings gives some hope of recovery for the fragile reef environment of the northern Bahamas. Other factors may reverse the optimism of course, not least the accelerating warming of the seas and the exponentially expanding pollution problem such as this, recently reported

This has been an opportunity to revisit the clear waters around Abaco where Melinda Rogers of Dive Abaco took these astonishing photos of coral on the local reefs. If the coral is destroyed or dies, this is what our children and their children will be be missing.

Click the brain coral to link to the Nassau Guardian Article

All photos, Melinda Rogers / Dive Abaco; Map, Sandy Estabrook; Nassau Guardian / Paige McCartney; Perry Institute for Marine Sciences (PIMS)

Reef Corals, Abaco Bahamas (Melinda Rogers / Dive Abaco)

OCTOPUS’S GARDEN (TAKE 9) IN THE BAHAMAS


Octopus (Melinda Riger - Grand Bahama Scuba)

OCTOPUS’S GARDEN (TAKE 9) IN THE BAHAMAS

We are back again under the sea, warm below the storm, with an eight-limbed companion in its little hideaway beneath the waves.

Octopus (Melinda Riger - Grand Bahama Scuba)

It’s impossible to imagine anyone failing to engage with these extraordinary, intelligent creatures as they move around the reef. Except for octopodophobes, I suppose. I’ve written about octopuses quite a lot, yet each time I get to look at a new batch of images, I feel strangely elated that such a intricate, complex animal can exist. 

Octopus (Melinda Riger - Grand Bahama Scuba)

While examining the photo above, I took a closer look bottom left at the small dark shape. Yes my friends, it is (as you feared) a squished-looking seahorse, 

Octopus (Melinda Riger - Grand Bahama Scuba)

The kind of image a Scottish bagpiper should avoid seeingOctopus (Melinda Riger - Grand Bahama Scuba)

OPTIONAL MUSICAL DIGRESSION

With octopus posts I sometimes (rather cornily, I know) feature the Beatles’ great tribute to the species, as voiced with a delicacy that only Ringo was capable of. There’s some fun to be had from the multi-bonus-track retreads currently so popular. These ‘extra features’ include alternative mixes, live versions and – most egregious of all except for the most committed – ‘Takes’. These are the musical equivalent of a Picasso drawing that he botched or spilt his wine over and chucked in the bin, from which his agent faithfully rescued it (it’s now in MOMA…)

You might enjoy OG Take 9, though, for the chit chat and Ringo’s endearingly off-key moments.

All fabulous photos by Melinda Riger, Grand Bahama Scuba taken a few days ago

Octopus (Melinda Riger - Grand Bahama Scuba)

 

YELLOWTAIL PARROTFISH: BAHAMAS REEF FISH (54)


Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

YELLOWTAIL (REDFIN) PARROTFISH: BAHAMAS REEF FISH (54)

The yellowtail parrotfish (sometimes known as a redfin) is one of around half-a-dozen kinds of parrotfish found among the coral reefs of the Bahamas, and sometimes in seagrass areas. There are many other related species worldwide (about 80). Parrotfish are among the most important fishes on the reef because they play a major role in BIOEROSION , a vital process for the health of the reef.

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

A. FEEDING & BEACH BUILDING

  • Their dental arrangements – a mouthful of meshing teeth – form the characteristic ‘beak’
  • Primarily herbivores but also snack on small creatures, organisms, or even molluscs
  • As they feed on their favourite algae, their teeth grind up the coral which they ingest
  • They digest the coral & excrete it as sand, becoming a component of your favourite beach
  • The teeth grow continuously, replacing ones worn away by grinding coral as they graze
  • They are a vital species in preventing algae from choking coral: essential reef cleaners

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

B. PARROTFISH: PERSONAL INFORMATION

  • Some secrete a protective mucous cocoon to sleep in or as concealment from predators
  • Mucous also helps to heal damage, repel parasites, & protect them from UV light
  • As they develop from the juvenile stage, most species change colour significantly
  • In some species, juveniles change colour temporarily for protective purposes
  • These are “sequential hermaphrodites”, turning from female to male (‘protogyny’)
  • Single males tend to have several lady friends, and aggressively defend their love rights
  • Parrotfish are PELAGIC SPAWNERS. Females release many tiny buoyant eggs into the water
  • The eggs float freely then eventually sink to the coral until they hatch
  • Unlike almost all other fishes, they use their pectoral fins to propel themselves
  • Feeding behaviour / dietary requirements make them (thankfully) unsuitable for aquariums (or aquaria, if you prefer)

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

WHAT WAS THAT ABOUT CHANGING SEX?

  • Parrotfish may undergo sex reversal in which developing female fish become males
  • Parrotfish born male remain male throughout their lives (“primary males”)
  • Female-born fish may change sex & colour to become male (“secondary males”)
  • Secondary males are fertile and generally mate with a single female
  • Females that stay female live in harems protected by a dominant “supermale” BUT…
  • …if the supermale dies, the largest female in the group changes sex to become male…
  • …AND amazingly adopts the coloration of the supermale (best ‘astounding fact’ of all)

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

ARE PARROTFISH EDIBLE? JUST ASKING…

  • Parrotfish skin is very tough but their flesh is soft and degenerates quickly
  • Some species (eg blue parrotfish) carry ciguatera toxins – to be avoided
  • They are not considered a fishing target in Bahamas, nor a food-fish
  • Parrotfish are eaten elsewhere in the world however, for example Jamaica (cooked)
  • In Hawaii they are eaten raw – at one time they were reserved for royalty

VIDEO LINK: PARROTFISH POOP

Credits: Melinda Rogers / Dive Abaco for her great illustrative images. All photographs were taken on the reefs of Abaco, before the devastation and destruction of Hurricane Dorian last September; Florida Museum to cross-check facts; VIDEO – Scientific American

Yellowtail (Redfin) Parrotfish (Melinda Rogers / Dive Abaco)

WRY ‘CUDA & SARDONIC SMILES, ABACO BAHAMAS


Barracuda, Abaco Bahamas (Melinda Rogers / Dive Abaco)

WRY ‘CUDA & SARDONIC SMILES, ABACO BAHAMAS

There’s no doubt about it, barracudas have a particularly unwelcoming look to them. They exude menace. There’s something about the torpedo shape, the primitive head, and the uncomfortably snaggle-toothed grin-with-underbite that suggests a creature not to be underestimated.

Barracuda, Abaco Bahamas (Melinda Rogers / Dive Abaco)

And that smiley mouth – rather scornful and derisive, is it not? A powerful creature in its element, where you are the intruder… and it sees it like that too. An adult barracuda may grow to nearly 6 foot long. Your are only temporarily of its world, and (it observes) you are keeping your distance.

Barracuda, Bahamas (Melinda Riger / G B Scuba)

The dental arrangements of a ‘cuda are a wonder in themselves. The teeth are razor sharp; an orthodontist’s nightmare because they are all different sizes and grow at different angles. Some are conventionally set in the jaws, but some actually grow from the roof of the mouth. There are ‘normal’ sized teeth interspersed with wicked-looking fangs that randomly grow facing forwards, backwards and sideways.

Barracuda, Abaco Bahamas (Melinda Rogers / Dive Abaco)

WHY THE UNTIDY MOUTH FURNITURE?Barracuda, Abaco Bahamas (Melinda Rogers / Dive Abaco)

The name Barracuda is thought to derive from the Spanish word barraco meaning (in one of its senses) “overlapping teeth”. The jaws that contain the teeth are strong, and the underbite adds to the effectiveness of ‘cuda predation. Prey is highly unlikely to escape once caught.  When the jaws snap shut, the sharp angled teeth – particularly the back-facing ones (cf fishhook barbs) prevent the victim from pulling away. Then the munching and shredding can begin inside what is essentially a perfectly equipped multi-bladed mincing machine.

Credits: Melinda Rogers / Dive Abaco except #3 & #8  Melinda Riger / Grand Bahama Scuba

Here’s looking at you…