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My name is Grouper Goodall. I’m a female Goliath Grouper writing a doctoral dissertation on human and grouper behavior. You can read more about my studies here.

During my research, I’ve discovered humans have an inexplicable need to dive with us. It’s true, we, Goliath Groupers, are a sexy bunch. Look at our burly torpedo-shaped bodies and our relaxed poise just hovering around like meditating yogis. We are adorable.

Now during spawning aggregation season (from August to October), we up the ante from adorable to awesome. After all, we’ve waited a whole year to have sex. So we gather at our singles bars, checking out sexy partners (if we can figure out who is the other sex) and we look our best. We call it courtship.

Goliath Grouper spawning aggregation or singles bar

Grouper Goodall and her buddies at a singles bar checking out sexy partners, if they can figure out who is the other sex. Photo Credit: Walt Stearns

During this critical time, your obsession for making us your dive buddies can easily get out of hand. Or fin. You’ll be surprised to know that in our grouper society, we have a code of polite behavior: a grouper etiquette. It has worked for the last 11 million years since the Miocene epoch. We are not going to change our ways, no matter how many selfie sticks you throw at us.

So, for your own good (and ours) I’ll share with you the basics of grouper etiquette.

Consider this an inter-species wake-up call

1) Avoid aggressive diving

We are irresistible, I know. But it’s rude and outright scary for us to see a diver approaching head on at full speed. I mean, when I see such locomotive divers, I pee my pants (If I could wear pants). We don’t follow Euclidean geometry. The shortest distance between you and me is not a straight line, but a soft curve. You should approach me gently, sideways. You’ll be surprised how close you can get to us. Obey this basic first rule of etiquette or you shall only see our tails.

2) Do not block the exit

Always give us a way out. Do you see where my head is? That means, if I decide to swim away from you in a jiffy, I’ll go towards where my head is pointing. So give me space or I might kick you in the gonads in my panic escape.

3) Do not chase after us

You might remember there was once a Jesus guy who said “let the children come to me”. It’s the same with us. You can get close to us, but for a photo portrait kind of close (when you do the citizen science project) don’t chase after us, of we’ll get the hell out of there. We’ll come up to check you out. Look, we are very curious. We like to pop up and ask you “Hello, What’s up? How’s it hanging? But, if you have a hose hanging in there, tuck it in. Come on, be a neat diver and don’t go around steamrolling the corals and the seabed. Not cool.

4) Do not feed us

We’ve worked out the whole year to look this magnificent for spawning season. We’ve done our yoga, eaten all the right foods. Yes, we might look a bit chubby to you but it’s the perfect kind of fat ass. Do you know how difficult it is to keep our spherical beauty? So don’t show up with hot dogs and who knows what. Feeding us breaks our delicate Rubenesque balance.


Remember, avoid aggressive diving, no blocking the exit, no chasing after us, and no giving us food.

I wish you a great diving experience. I’ll be watching you.


blog-edited-gg-citizen-scienceWhen you SCUBA dive in Florida, you can become a citizen scientist.

Think taking selfies of Goliath Groupers.The Goliaths don’t have opposable thumbs like primates (monkeys, apes, us), so holding a camera underwater (or a cell phone) will be impossible for the groupers. But you can do the selfie for them. And in doing so, you can make a great contribution to my research on Goliath Grouper behavior, and to the advancement of science in general.

There are unique marks on the animal’s face (facial markings) that make individual identification possible. And when you can tell one Goliath Grouper from another, that’s when you can start doing some serious science in animal behavior and conservation.

The master plan is to photo-selfie all Goliath Groupers in Florida. It will take many divers, and many dives. Every single selfie you take will help the research. Even if you suspect you are selfy-ing the same Goliath over and over.

Here’s what to do.

You can take a frontal selfie like this (the grouper is looking straight ahead at you)

Goliath closeup Sarah FriasTorres jpeg

Goliath Grouper frontal selfie. Copyright: Sarah Frias-Torres

or a profile selfie like this (the grouper head is looking to one side). If you can only photograph one side, take the LEFT side (fish looking left). If you can photograph both sides of the same fish, that’s even better!

Goliath Grouper meets Dr. Sarah Frias-Torres

Goliath Grouper profile selfie. Copyright: Mark Eakin

As soon as you can,  write down:

WHEN (date) & WHERE (dive site)

Send me PHOTO, WHEN & WHERE to

I’ll be posting information on this blog as selfies start to arrive.

Let’s go diving!

The Goliath groupers are on their honeymoon. As a diver, you can use your dive time to do science and actively contribute to the conservation of these gentle giants. All you need to do is count fish. Here’s how.


Goliath groupers are critically endangered throughout their tropical and subtropical Atlantic ocean distribution. In the United States, a federal and state moratorium on harvest implemented in 1990 has allowed a slow path towards recovery from near extinction. Diving in Florida will allow you to see Goliath groupers during the most spectacular time of the year: spawning season.

Every year, from mid August to early October, Goliath groupers travel from around the state of Florida to congregate at a few sites along the Florida coastline (from north of Miami to the Jupiter area) for the purpose of breeding. These congregations are spawning aggregations. The peak spawning season is September. Goliaths remain for several weeks at the spawning aggregation sites checking each other out, and seeking potential mates with an elaborate courtship. Spawning occurs either at the full moon or the new moon (scientist are still looking into this).


You can dive for science if you know how to count fish and you can tell apart a light color fish from a dark color fish.

How to count fish like a scientist.

As you start your dive, count Goliath groupers every 10 minutes. You will count all the Goliaths around you, in a 360 degree field of view. To do so, you turn slowly around on yourself, like a little planet Earth rotating on its axis, counting as you turn, until you reach your starting point. You already learned to count numbers in kindergarden, so I will not elaborate any further. Why is this important? Because knowing how many fish you see at each dive site helps scientists like me to evaluate the health of the population

How to count colorful fish like a scientist.

As males and females seek each other out and engage in courtship they change their “color”, or in this species, their color “tone” from light to dark. There are 4 color phases (check out the photo below)

Normal (N) – typical brown blotches you see year round

Light (L) – The fish body is all white or very light

Dark (D) – the fish body is all black or very dark

Bicolor (B) – The fish has a white head and a dark body

Goliath groupers and their color phases. Photo Credit: Mike Phelan, Alang Chung

Goliath groupers and their color phases. Photo Credit: Mike Phelan, Alang Chung

Each color phase has an “assigned sex”, this means, scientists suspect what sex belongs to each color phase, but the groupers are not willing to provide a sample of their eggs or sperm as they pass by the unsuspecting scientific diver. For now, we think the Normals are males or females not engaged in courtship. Once the Goliaths engage in courtship, the Lights are females, the Darks are males, and the Bicolors are dominant males.

To count the number of Goliath grouper in each color phase, after your first count, you will do another 360 rotation around yourself, this time you are counting how many groupers in each color phase you see. It’s easier to look for the Lights, Darks and Bicolors as they stand out. Everything else will be Normals.  Why is this important? Because knowing how many Goliath groupers are in each color phase helps scientists like me to quantify how active is the spawning aggregation.

How to enter data like a scientist

1 – Bring a dive slate with you, with a pencil. The slate can be any size comfortable to you

2- On the top of the dive slate write DATE, TIME IN , DIVE SITE. You fill in that information after you complete the dive

3- As a reminder to yourself, under the date, time in and dive site lines, write down the color phases and their abbreviations,

N = Normal, L = Light, D = Dark, B = Bicolor

4 – Dive, dive, dive. Every 10 minutes count the number of Goliaths (your first 360 rotation) then count the number in each color phase (your second 360 rotation). Depending on whether you are diving air or nitrox, you will do 2 counts or 3 counts per dive.


Let’s say in your first rotation you count 10 Goliath groupers. You write down the number 10. On your second rotation you count 2 Lights, and 2 Darks (easier to see among the Normals). So right next to the 10 (your first count) you write 2 L, 2D, 6N.


Please email me the data

If you have photos or video of Goliath groupers, and you know WHEN and WHERE you took them consider sharing them with me for the purpose of science.

You are welcome to post comments here or email me your questions/comments

Safe diving ! Please, read the diving etiquette below.

Goliath grouper etiquette.003.003

This year, 2013, the critically endangered Goliath grouper is once again under review by the Florida Fish and Wildlife Conservation Commission (FWC), the Gulf of Mexico Fishery Management Council, the South Atlantic Fisheries Management Council and the National Marine Fisheries Service (NMFS) . On the table, the possibility of lifting the 1990 federal and state moratorium on harvest for this fragile species.

I have provided up-to-date information in my previous posts: Guilt-free Goliath groupers and Goliath groupers under review.  Below are 5 common myths on Goliath grouper used to justify requests for lifting the current moratorium. The myths are contrasted with data obtained from scientific research done my myself and others.

Goliath groupers were fished to near extinction in the United States. Trophy fishing in the 1950s; Key West, Florida. Credit: anonymous

PAST: Goliath groupers were fished to near extinction in the United States. Trophy fishing in the 1950s; Key West, Florida. Credit: anonymous

TODAY: Goliath grouper spawning aggregation re-forming in east Florida after being fished to extinction. Credit: Walt Stearns

TODAY: Goliath grouper spawning aggregation re-forming in east Florida after being fished to extinction. Credit: Walt Stearns

Myth #1

Goliath groupers eat all the groupers, snappers and lobsters on the reef, contributing to fisheries declines.

The Science Answers: False.

In Goliath grouper, poor development of canine teeth reflects a generalized diet [1]. Analysis of stomach contents [2,3,4] reveal that diet is restricted to invertebrates, mostly shrimp and crabs, lobsters, gastropods, and poisonous or venom-spined slow-moving fish ( stingrays – Dasyatidae; cowfish – Ostraciidae; burrfish and pufferfish – Diodontidae; catfish – Ariidae). Food web dynamics based on carbon and nitrogen stable isotope analyses in goliath grouper confirm the diet preferences (invertebrates and poisonous slow moving fish) obtained through previous dentition and stomach content studies. The isotope analyses indicated a broad prey base with a relatively high trophic status [5], but not to the level of a top predatory fish as the myth explains. The most comprehensive study to date [6] demonstrates that: 1) Goliath groupers are not the cause for declining fish and lobster stocks.  Overfishing is the main cause; 2) Goliath groupers function as a top-down control on juvenile lobster predators, ensuring more lobsters reach adult size and become available to the lobster fishery; and 3) goliath groupers could provide additional ecological and socioeconomic benefits:  in ecotourism, and as potential bio-control of the invasive Indo-Pacific red lionfish Pterois volitans on Atlantic reefs.

Myth #2

Goliath grouper grow at a formidable speed to reach such a big size, so they must eat huge amounts of grouper, snappers and lobsters to grow that fast.

The Science Answers: False.

The goliath grouper diet is explained in myth #1. As for a formidable speed of growth, we must focus on the juvenile phase. Fish have indeterminate growth, which means, they keep increasing in length and weight throughout their life, unlike us and other mammals, who reach our maximum length (height in our case) at a determined adult age. During the juvenile phase (from birth until reaching sexual maturity), fish experience their fastest growth rate, which then decreases progressively throughout the rest of their life.

Goliath grouper juveniles migrate from their mangrove juvenile habitat to their adult reef habitat at about 8 years old, measuring 110 cm-120 cm in length [3]. This gives a maximum juvenile growth rate of 15 cm/year or 6 inches/year, as the maximum growth speed during the lifetime of an individual goliath grouper. This is the same speed at which our hair grows (!). Obviously not a mythical speed of growth.

Myth #3

Goliath grouper are a pest. They are everywhere.

The Science Answers: False.

This myth is a common problem of the “shifting baselines syndrome” [7], whereby fishers accept abundance and size information from more and more recent periods as baselines. Once commercial extinction occurred in the late 1980s, goliath grouper were absent in Florida reefs. Such absence became a new baseline, to the new anglers and spearfishers moving to Florida. Since the 1990 fishing moratorium, goliath grouper are in a path of recovery, slowly returning to their original distribution area. Therefore, every new grouper encountered represents a 100 % increase for someone with a zero-grouper baseline.

Site attachment, available habitat and spawning aggregation behavior [3,8, 9] also contribute to perceiving goliath grouper as a pest. Goliaths usually remain in the same site after they recruit to the reef. Hence the abundance of one single goliath grouper is multiplied by as many fishers or divers that have encountered it. Available hard bottom structure, specially in regions which lack natural reef habitat or where this habitat has been degraded, also concentrates goliath groupers, giving an artificial perception of over-abundance to the observer. Finally, spawning aggregations concentrate all the adult goliath grouper throughout the reef in one single location, compounding a false sense of overabundance to the casual observer. Only the few “old-timers” left in Florida, those that were fishing in the 1950s and 1960s, have experienced the extinction and path towards recovery of goliath grouper. Interestingly, these fishers are the most supportive of continued goliath grouper conservation.

Myth #4

Re-opening the fishery will provide a healthy food source for consumers. 

The Science Answers: False.

We must remember that goliath grouper reached commercial extinction in the late 1980s. The species is extremely vulnerable to overfishing due to its slow growth, long life (possibly exceeding four decades), late sexual maturity (up to 8 years), strong site fidelity, the formation of spawning aggregations, and being unafraid of divers (even those with spearguns) [3,8]. Even recreational fishing could be extremely damaging as it has been demonstrated for other fish species: recreational landings in the US seriously impact many of the most-valued overfished species [10].

When the fishery existed, goliath groupers were mostly targeted for trophy fishing, that is, catching the biggest fish for show and tell. When the fish meat was used, 90 % of it was ground for fertilizer use or ended up in canned food for pets (dogs and cats). There were several reports of drugs being smuggled inside the carcasses of dead goliaths, in their way to northern states. The closure of the fishery did not result in direct starvation to any US citizen.

While it is true goliath grouper are the largest grouper fish in the Atlantic ocean, and the second largest grouper fish in the world, just behind the giant grouper of the Indo-Pacific (Epinephelus lanceolatus), big size does not necessarily translate to food source. Here, we must be concerned about health risks. Since goliath grouper are a coastal species, with a prolonged juvenile phase living in mangrove habitats, they accumulate in their tissues the pollution we generate in our modern way of living, by the effect of bioaccumulation (toxins ingested with their prey). Indeed, muscle tissue in goliath grouper commonly contain methyl mercury -a toxic form of mercury which causes dangerous cardiovascular and neurological effects in humans-, often exceeding the United States governmental advisory criteria for human health [5]. Goliath grouper also die when red tides, or Harmful Algal Blooms (HABs) from the dinoflagellate algae Karenia brevis, occur. Brevetoxin (a toxin produced by the dinoflagellate) is a potent neurotoxin that causes serious illness in humans who ingest marine life containing the toxin, or if they inhale the toxin aerosols [11]. HAB-originated fish kills in which huge numbers of goliath grouper die occur during multi-species mortality events, when manatees, dolphins and seaturtles also die. It has been demonstrated that the cause of death for the marine mammals is due to the ingestion of prey which contained the brevetoxin, and by the process of bioaccumulation, enough brevetoxin accumulated in the animal’s tissues to become the cause of death [12]. Preliminary data suggest brevetoxin accumulation is also the cause of death in goliath grouper (Frias-Torres, unpublished data). Hence, consumption of goliath grouper fillets could pose an additional brevetoxin health risk for humans. Finally, studies on pesticide levels contained in goliath grouper tissue have not been completed, but it is possible they follow a similar bioaccumulation pattern than that of methylmercury and brevetoxin.

Myth #5

There are too many goliath grouper out there. We must use this resource for the benefit of the fishermen, so we have to do something about this, such as a limited recreational take, with a tag or permit system.

The Science Answers: False.

The perception of goliath grouper invading every crevice of the reef has been discussed in myth #3, and is due to the “shifting baselines syndrome” explained there.

Spearfishers and hook-and-liners wiped out the goliath grouper population in U.S. waters in the late 1980s reaching commercial extinction [3, 13]. Goliath grouper are extremely easy to catch: they are unafraid of divers, they present site attachment (remain in the same site once they recruit to the mangroves as juveniles and to the reef as adults), and all the goliaths of the State congregate once a year at a reduced number of sites to form spawning aggregations, and reproduce. It will be extremely difficult to justify the socioeconomic, management and ethical reasons for opening a limited recreational take, mainly due to the potential health risks for human consumption (explained above), the lack of “sport” in killing such a catchable species, and the potential of localized extinction events when tags or permits were used in a short time window or limited geographic range.

A live goliath grouper is more valuable than a dead one. And here relies the true benefit for fishers and other Florida taxpayers. Tourists come from all over the country, and all over the world just to scuba dive with goliath grouper. This is a tremendous source of tourist dollars for the state of Florida, not only for the diving business – each diver pays $100-$140  for a two-tank dive, depending on gear rented-, but also for the associated businesses, as the tourist-divers need to eat, sleep, and drive. Ironically, the same qualities that make goliath grouper extremely vulnerable to overfishing and extinction, also make them a great ecotourist attraction: they are huge, long-lived, unafraid of divers, remain in the same reef site, and form spawning aggregations.

Direct benefit to fishers and the state of Florida also relies on other potential ecosystem services goliath grouper provide, specially in these times of economic and environmental crisis. The invasive Indo-Pacific lionfish (Pterois volitans) is a voracious predator of juvenile reef fish and it is causing major disruptions in Atlantic reefs, in conjunction with habitat destruction and global climate change [14]. The lack of big predators able to feed and survive the poisonous spines of lionfish favors the expansion of this invader. However, the goliath grouper’s adaptation to feed on slow-moving venom-spined or skin-poisonous fish (catfish, stingrays, cowfish, burrfish, pufferfish), could potentially become our best ally to fight against such destructive invader, and perhaps successfully preserve and rebuild Florida’s reef fish communities.

Literature Cited

[1] Smith CL. 1971. A revision of the American groupers: Epinephelus and allied genera. Bulletin of the American Museum of Natural History 146, 69-241.

[2] Bullock LH, Smith GB. 1991. Seabasses (Pisces: Serranidae). Memoirs of the Hourglass Cruises 8 (2), 1-243.

[3] Sadovy Y, Eklund AM. 1999. Synopsis of biological information on the Nassau Grouper, Epinephelus striatus (Bloch 1792), and the jewfish, E. itajara (Lichtenstein 1822). NOAA Technical Report NMFS 146, Seattle, Washington. 65 pp.

[4] Koenig CC, Coleman FC. 2009. Population density, demographics, and predation effects of adult goliath grouper (Epinephelus itajara). Final Report to NOAA MARFIN for Project NA05NMF4540045.

[5] Evers DC, Graham RT, Perkins CP, Michener R. 2009. Mercury concentration in the goliath grouper (Epinephelus itajara) of Belize: and anthropological stressor. Endang. Species Res. 7:249-256. Open Access

[6] Frias Torres, S.  2013.  Should critically endangered goliath groupers, Epinephelus itajara, be culled in Florida?  Oryx 47 (1):  88-95.

[7] Pauly D. 1995. Anecdotes and the shifting baselines syndrome in fisheries. Trends in Ecology and Evolution 10: 430.

[8] Frias-Torres S. 2006. Habitat use by juvenile goliath grouper, Epinephelus itajara, in the Florida Keys, USA. Endangered Species Research 2: 1-6. Open Access

[9] Frias-Torres S, Barroso P, Eklund A-M, Schull J, Serafy J. 2007. Activity patterns of juvenile goliath grouper, Epinephelus itajara, in a mangrove nursery. Bulletin of Marine Science 80: 587-594.

[10] Coleman FC, Figueira WF, Ueland JS, Crowder LB. 2004. The impact of United States recreational fisheries on marine fish populations. Science 305: 1958 – 1960.

[11] Steidinger KA. 1993. Algal Toxins in Seafood and Drinking Water (ed. Falconer, I.) 1-28 , Academic Press, London.

[12] Flewelling LJ and 20 authors. 2005. Red tides and marine mammal mortalities. Nature. Vol 435: 755-756

[13] McClenachan L. 2009. Historical declines of goliath grouper (Epinephelus itajara) populations of South Florida, USA. Endang. Species Res. 7:175-181. Open Access

[14] Albins MA, Hixon MA. 2008. Invasive Indo-Pacific lionfish (Pterois volitans) reduce recruitment of Atlantic coral-reef fishes. Mar Ecol. Prog. Ser., 367:233-238.

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