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)

SEA URCHINS: PICTURE PERFECT ABACO (11)


SEA URCHINS: PICTURE PERFECT ABACO (11)

Sea Urchin, Abaco, Bahamas (Melinda Rogers / Dive Abaco)

As every swimmer knows, or eventually finds out the hard way, it’s not only Blue Suede Shoes that should not be stepped on. But however painful the consequences of a misstep, it’s hard not to find some beauty in an urchin living in a thriving reef environment. The wonderful anatomical diagram by Alex Ries shows everything you could conceivably want to know about one of nature’s most proficient foot-stabbers (if only all such diagrams were presented so simply and clearly).

Sea urchin anatomy (Alex Ries)

The internal organs depicted resemble a bad trip in the bowels of a vacuum cleaner; or (narrow your eyes) an experimental painting from one of the less successful schools of early c20 modern art, soon to be swept aside by Cubism. Note that the mouth is located where you might expect to find the opposite end, and vice versa.

I photographed the urchin test (skeleton) below at Delphi. It was large and almost entirely undamaged (very rare in my experience). The bright faintly greenish white is set off by the palest of pinks. Whatever your view of how creatures came to exist, imagine the creation or evolution of calcium carbonate into a small symmetrical structure as beautiful, detailed and complex as this. If you are short of a lockdown recreation, maybe try to draw it.

Sea Urchin Test / Skeleton, Abaco Bahamas (Keith Salvesen / Rolling Harbour Abaco)

Photo credits: #1 Melinda Rogers / Dive Abaco; #2 Anatomy Diagram, Alex Reis (5 stars for making it available free on Wikimedia); #3 Keith Salvesen / Rolling Harbour Abaco

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).

SPERM WHALE BONES & RESEARCH: LIFE AFTER DEATH


SPERM WHALE BONES & RESEARCH: LIFE AFTER DEATH

I made this short video last year at BMMRO HQ, Sandy Point, Abaco. A sperm whale had stranded earlier in the year, and after the necropsy some of the bones were taken from the beach for research. In order to clean them, the bones were sunk and anchored to the seabed offshore in quite shallow water. Strandings are always sad, of course, but  it is good to know that even after death the creature makes an important contribution to scientific research. In a sense, it has life after death.

BMMRO / Rolling Harbour Abaco / Keith Salvesen

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

MANATEES: PICTURE PERFECT ON ABACO (4)


MANATEES: PICTURE PERECT ON ABACO (4)

MANATEE APPRECIATION DAY 2020West Indian Manatee, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Mrs RH and I are sticking to self-isolation right now (we are fine, but thank you for asking). However I am already breaking my current self-imposed ‘single-picture-and-not-much-writing’ regime with today’s creature feature. The excuse? It is of course the last Wednesday in March and as everyone must know it is Manatee Appreciation Day.

Anyone can (and indeed should) appreciate manatees anywhere at any time, and their contemplation is a way to lift the spirits. They were first found in Abaco waters about a dozen years ago. BMMRO reported their movements and the ongoing research. Later, Bahamian locals enthusiastically followed the lives of Gina, Rita, Georgie, Randy & co; and the calves such as JJ and Sayle (winning name in a public competition). Citizen scientist reports were invaluable to the research. Unsurprisingly, since Hurricane Dorian reports have greatly reduced. Manatees may well still be around but even now, 6 months later, trichechi sightings are sporadic. There are other concerns, after all.

West Indian Manatee, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Manatees love the camera and, Madonna-like, are often pleased to ‘strike the pose’. Of a sort.

West Indian Manatee, Abaco, Bahamas (Charlotte Dunn / BMMRO)

West Indian Manatee, Abaco, Bahamas (Charlotte Dunn / BMMRO)

Today the Marine Conservation Society (MCS) showed their appreciation for manatees with a superb image and an excellent set of Manatee Facts that I recommend to anyone who has read this far. For example, recent broadcasts and news articles have featured the importance of seagrass. You will see that it is the primary diet of manatees. 

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Happy #ManateeAppreciationDay! ☺️ We have a great photo-feature of these amazing animals in the Spring issue of our magazine coming to all members in the next few days but whilst you wait, here are some fun facts about them: ⠀ ⠀ 💙The manatee, also known as a 'sea cow', is a large marine mammal with an egg-shaped head, flippers and a flat tail. ⠀ 💙Manatees range in size from 8 to 13 feet (2.4 to 4 meters) and can weigh 440 to 1,300 lbs. (200 to 590 kilograms). ⠀ 💙Although they may seem like cumbersome creatures, manatees can swim quickly and gracefully.They have strong tails that power their swimming and usually swim about 5 mph but they can swim up to 15 mph (24 km/h) in short bursts ⠀ 💙There are three species of manatee: the Amazonian manatee, the West Indian/American manatee and the African manatee. ⠀ 💙Manatees often swim alone or in pairs. If manatees are seen in a group (called an aggregation), it is either a mating herd or an informal meeting of the species simply sharing a warm area that has a large food supply. ⠀ 💙Manatees are herbivores. At sea, they tend to prefer sea grasses. When they live in rivers, they consume freshwater vegetation. Manatees also eat algae. It's reported that a manatee can eat a tenth of its own weight in 24 hours! ⠀ 💙The IUCN's Red List of Threatened Species lists all manatees as vulnerable or endangered and facing a high risk of extinction. ⠀ Manatees are thought to have evolved from four-legged land mammals more than 60 million years ago. Except for the Amazonian manatee, their paddlelike flippers have vestigial toenails — a remnant of the claws they had when they lived on land. ⠀ 💙Manatees' eyes are small, but their eyesight is good. They have a special membrane that can be drawn across the eyeball for protection. ⠀ 💙Manatees don't always need to breathe. As they swim, they poke their nose up above the water's surface to catch a few breaths every few minutes. If they are simply resting, they can stay under the water for 15 minutes without taking a breath ⠀ ⠀ #marinemammal #marineconservation #marnebiology #marinelife #oceanlife #oceanindoors #manatee ⠀ ⠀

A post shared by Marine Conservation Society (@mcs_uk) on

Credits: Photos #1 – #4 Charlotte Dunn / Bahamas Marine Mammal Research Organisation (BMMRO) and #5 Caine Delacy / BMMRO; MCS UK

MCS links: https://www.mcsuk.org; https://www.facebook.com/mcsuk/

Gina with her calf SayleWest Indian Manatee, Abaco, Bahamas (Caine Delacy / BMMRO)

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)