GROUPER AT THE CLEANERS: PICTURE PERFECT BAHAMAS (5)

March 29, 2020 by Rolling Harbour

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

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

MEET ARNOLD: BE A BAHAMAS BLACK GROUPER GROUPIE

June 11, 2019 by Rolling Harbour

MEET ARNOLD: BE A BAHAMAS BLACK GROUPER GROUPIE

The Black Grouper, like all its cousins, has the twin disadvantages of being fished for sport and fished for food. As demand for grouper on the menu rises, so does its vulnerability. The species is described as a ‘slow breeder’, so a depleting population has less chance of sustaining numbers. The consequence is an exponentially diminishing stock of the species. The equation is simple: fewer fish means less and less stock replenishment.

Formerly plentiful, these groupers (like other grouper species) have moved from an IUCN listing of ‘Least Concern’ to ‘Near-Threatened’. Whatever effect climate change may be having on the oceans, stock depletion of this noble species also has more direct human causes.

An adult black grouper’s diet consists of small fish and squid. Juveniles feed primarily on crustaceans. However, certain tiny reef fish – blennies and gobies for example – are important to the species as ‘cleaners’. You can read about their significance by clicking CLEANING STATIONS.

The service performed by tiny fish on large ones (not only groupers) is an example of a symbiotic relationship known as ‘mutualism’**, in which both parties benefit (the little fishes get gacky bits of grouper to eat). The cleaners are able to do their work inside the gills and even the mouth of the host without being at risk.

The NASSAU GROUPER has a defined and enforced closed season to help maintain numbers. It will be interesting to see if the same protection is eventually extended to the black grouper and indeed to other grouper species.

** The other two types of symbiotic relationship are commensalism, in which only one species benefits while the other is neither helped nor harmed; and parasitism, where one creature (the parasite) gains, while the other (the host) suffers.

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Credits: all photos Melinda Riger of Grand Bahama Scuba

‘CURIOUS GEORGE’ THE INQUISITIVE BLACK GROUPER

May 4, 2018 by Rolling Harbour

‘CURIOUS GEORGE’ THE INQUISITIVE BLACK GROUPER

Fish, like humans, have a wide variety of temperaments, or so it seems. Resorting to anthropomorphic analysis of animal behaviour is a favourite pastime for humans. Who really knows if a creature is actually feeling shy or confident or playful or aggressive or indeed inquisitive. Often it just seems that way and we are happy to categorise dolphins as playful, sharks as vicious, angelfish as serene, small darting fish as timid and so on.

Occasionally a creature displays a ‘human’ characteristic that seems undeniable. One such is Curious George. He has become used to the divers around the reef where he lives, and greets them. He enjoys the photography sessions and the equipment, even though they may be for recording other fish. He demonstrates inquisitiveness for the strange-looking black-suited creatures that visit his patch. Like many groupers, he likes to be gently patted and stroked.

All this curiosity and friendliness evidences a benign interspecies relationship of symbiotic mutualism, through which both species (man and fish) benefit from the interaction. The mutually beneficial feeling might in broad terms be described as ‘pleasure’.

Or maybe I am just indulging in a bit of over-anthropomorphisation (if there is such a word)…

All photos by one half of the symbiotic mutualism here, Melinda Riger (Grand Bahama Scuba)

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)

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

JAW-DROPPING: GROUPERS AT THE CLEANERS

June 6, 2017 by Rolling Harbour

Grouper at cleaning station - Melinda Riger @ GB Scuba

JAW-DROPPING: GROUPERS AT THE CLEANERS

In some of these photos you’ll notice tiny fish attending to the grouper. These are CLEANERS and they are an essential part of the bodily and oral hygiene routine for larger fish species. The big fish call in at so-called CLEANING STATIONS, where the tiddlers remove parasites and dead skin, and polish up the gills. They will even enter the fish’s mouth to pick bits from between its teeth – the deal being that they will not be eaten. This mutually beneficial arrangement is called ‘cleaning symbiosis’ and is carried out by (for example) gobies, wrasses and cleaner shrimps.

Pederson’s cleaner shrimps and cleaner wrasse

Some of these photos show groupers with open gills as well as open mouths, an invitation to the cleaners to do their work. I’d intended to write about how and why gills work but I’ve thought better of it. There’s a lot of detail about chemical exchange involved that, when I looked more closely, seemed rather dull… and therefore outside the remit of this blog, which includes trying to avoid ‘dull’. If you really want to know more, Wiki has a good article HERE. Good luck with that….

Credits: All photos Melinda Riger, Grand Bahama Scuba

BAHAMAS REEF FISH (22): BLACK GROUPER

February 4, 2015 by Rolling Harbour

BAHAMAS REEF FISH (22): BLACK GROUPER

The Black Grouper is a large fish of the reefs found in the western Atlantic, particularly in the waters of Florida, Bahamas, Caribbean and the Gulf of Mexico. It is a solitary species that mostly prefers the shallow waters around coral reefs.

Formerly plentiful, these groupers (like other grouper species) have moved from an IUCN listing of ‘Least Concern’ to ‘Near-Threatened’. They have the twin disadvantages of being fished for sport and fished for food. As demand for grouper on the menu rises, so does its vulnerability. The species is described as a ‘slow breeder’, so a depleting population has less chance of sustaining numbers.

An adult black grouper’s diet consists of small fish and squid. Juveniles feed primarily on crustaceans. However, certain tiny reef fish are important to the species as ‘cleaners’. You can read about their significance by clicking CLEANING STATIONS Here are examples of two black groupers receiving attention at the same cleaning station. Both also seem to be giving a ride to REMORAS.

Note that this fish has an embedded hook and is trailing a line – one that ‘got away’

Despite the name, black groupers are not all black. They have many shades from dark to olive-coloured to pale. I believe the two photos below are of a grouper known as Arthur, a favourite with divers and definitely off the menu…

The tiny bright blue fish in the photo above are Blue Chromis, a regular accompaniment on any snorkel or dive on a reef. I like the colourful little Fairy Basslet in the next photo

Now that the NASSAU GROUPER has been awarded a closed season to help maintain numbers, it will be interesting to see if the winter fishing ban is extended to the Black Grouper…