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Common Name:
Red Grouper

Synonymy:
Serranus morio (Valenciennes in Cuvier and Valenciennes, 1828)

Other Taxonomic Groupings:
Superclass: Osteichthyes
Subclass: Neopterygii
Infraclass: Teleostei
Superorder: Acanthopterygii

Species Description:
The red grouper, Epinephelus morio, is a moderately sized, robust grouper that grows to approximately 125 cm (4.1 feet) and may weigh 23 kg (50.7 pounds) or more.  Most, however, do not achieve this size.   Body depth is less than head length. Eyes are large, and the nostrils are unequal in size, with the posterior pair slightly larger than the anterior pair.  The preopercule has somewhat enlarged serrae present on the angle.  The opercule has a straight upper edge and 3 flat spines, with the center spine being the most elongate.  There are 15-16 gill rakers on the lower limb of gill arch.  Scales are small and ctenoid, numbering 60-68 along the lateral line.  The dorsal fin has 11 spines, the second of which is the longest.  The soft dorsal has 16-17 soft rays.  The interspinous membrane is not notched.  The anal fin has 3 spines and 8-10 soft rays.  The pelvic fins are shorter than the pectoral fins.  The bases of soft dorsal and anal fins have scales and thicker skin.  The caudal peducle lacks a saddle.  The caudal fin is truncate.  Body color is highly variable, but typical color is dark red to reddish brown, fading to pink or lighter red on the sides and ventral surface.  Whitish spots and blotches are scattered over the body surface, with small black dots around the eyes.  The dorsal, anal, and caudal fins all have dark outer margins.  When resting, the color pattern may become banded, as occurs in the Nassau grouper, E. striatus (Bohlke and Chaplin 1964; Fischer 1978).   

Potentially Misidentified Species:
The red grouper is distinguished from other members of its genus by the second dorsal spine, which is the longest; and by the interspinous membrane, which is not notched as it is in other Epinephelus species.  Further, the pelvic fins in the red grouper are shorter than the pectorals and are inserted posterior to the pectoral fin base.  The opposite condition is true for the Warsaw grouper, E. nigritus; the yellowedge grouper, E. flavolimbatus;  and the misty grouper, E. mystacinus;  all of which have longer pelvic fins than pectoral fins, and have the pelvic fins inserted anterior to the pectoral fin base. 

Red groupers are distinguished from members of the Mycteroperca by having a shorter body, 11 dorsal spines, 9 soft rays on the anal fin, and by thicker skin at the bases of the dorsal and anal fins (Fischer 1978).

II.  HABITAT AND DISTRIBUTION 

Regional Occurrence:
Ephinephelus morio ranges from New England south through Bermuda, Florida, the Gulf of Mexico, the Bahamas and the Caribbean, to southeastern Brazil (Bohlke and Chaplin 1968, Fischer 1978).  Occurrences of this species north of the Carolinas are thought to be due to larval transport in the Gulf Stream rather than from immigration of adults (Thompson and Munro 1978).   

Primarily a continental species, E. morio has the widest distribution of all western Atlantic groupers (Roe 1976).  Its center of abundance extends from the Florida shelf into the eastern Gulf of Mexico (Moe 1969).  It becomes more rare in the West Indies (Randall 1968). 

IRL Distribution:
While juveniles are common inhabitants of seagrasses and shallow reef areas in south Florida, they occur less often inside the IRL.  Fish less than 6 years old can be found in nearshore reefs.  Adults occur in offshore hardbottom habitats, where they are harvested commercially and recreationally.

III. LIFE HISTORY AND POPULATION BIOLOGY

Age, Size, Lifespan:
Red grouper grow to 125 cm (4.1 feet) total length (TL) and may weigh 23 kg (50.7 pounds), though most are harvested at 70 – 72 cm (27.5 - 28.3 inches) TL (Jory and Iversen 1989).  Males and females grow at approximately similar rates, though males tend to reach larger adult size (Jory and Iversen 1989).  They may live 30 years or more (Moe 1969;  Beaumariage and Bullock 1976).  

Moe reported that red grouper grow at a rate of 5.8 - 10.3 mm (0.22 – 0.40 inches) per month. 

Abundance:
Epinephelus morio is more abundant in the eastern Gulf of Mexico and in south Florida than it is in east central Florida.  

Reproduction:
Red grouper, like most serranid fishes, are protogynous hermaphrodites, beginning life as females, with some later transforming into males.  Females mature at approximately 35 – 50 cm Standard length (SL), at about 4-6 years of age (Heemstra and Randall 1993), but reach their greatest reproductive potential when they are 8-12 years of age. 

Females transform to males between ages 7-14, at a rate of approximately 15% per year.  Transition to male can occur when females reach 27 cm (10.6 inches) SL, but most commonly occurs after females grow to 50 cm (19.7 inches) SL (Jory and Iversen 1989).  Males comprise approximately 10% of all year classes until approximately age 9 when males reach 50 cm (19.7 inches) SL.  Sex ratios are not equal until approximately age 15, when most red groupers have reached 63 cm (24.8 inches) SL (Moe 1969;  Beaumariage and Bullock 1976;  Jory and Iversen 1989). 

In the eastern Gulf of Mexico, spawning occurs from January through June, peaking in March and May in waters 19 – 21 ºC, and 20-90 m deep (Roe 1969; Johnson et al. 1998).  Females with oocytes in varying stages of development are collected throughout the spawning season, suggesting that red grouper are likely to be batch spawners. 

Female fecundity ranges from 312,000 – 5.7 million eggs per female, depending on size (Moe 1969).

Embryology:
Ephinephelus morio eggs are pelagic, measuring less than 1mm in diameter and having a single oil globule.  Larval red grouper leave the plankton after approximately 1 month and metamorphose to benthic juveniles when they reach approximately 20-25 mm SL (Beaumariage and Bullock 1976).

IV.  PHYSICAL TOLERANCES

Temperature:
Roe (1976) reported red grouper to a depth of 189 m, where bottom temperatures ranged from 15 – 30 ºC. 

Other Physical Tolerances:
Stout (1980) reported that red grouper in the southeastern United States had an average of 0.0008 ppm DDT, and undetectable levels of PCB’s compared to other fishes. 

V.  COMMUNITY ECOLOGY

Trophic Mode:
All groupers are unspecialized and opportunistic in their feeding habits.  Red grouper are among the top predators in reef community food webs and may control some aspects of community balance in reef systems (May et al. 1979).  The diet is varied but commonly includes lutjanid and sparid fishes, as well as many types of invertebrates including xanthid and portunid crabs, spiny lobster, snapping shrimp, stomatopods, octopus, and squid and penaeid shrimp, especially the pink shrimp (Penaeus duorarum) (Longley and Hildebrand 1941; Moe 1969; Costello and Allen 1970). 

Red grouper are highly susceptible to the effects of red tide organisms, and were extirpated from reefs 12-15 m off Sarasota, Florida in 1991 as the result of red tide poisoning (Heemstra and Randall 1993). 

Competitors:
Groupers likely compete interspecifically due to overlapping food habits, space and habitat requirements (Thompson and Munro 1978).  Groupers are also likely to compete for prey with other large species such as jacks, snappers, barracuda, and sharks. 

Predators:
Predators of smaller groupers include other groupers and moray eels  Larger groupers are likely preyed upon by sharks, among them the sandbar shark, Carcharhinus plumbeus;  and the great hammerhead, Sphryna mokarran (Compagno 1984). 

Parasites:
Groupers suffer from a number of parasites including digenetic trematodes, cestodes, and nematodes (Manter 1947; Overstreet 1968; Fajer et al. 1979).   Trematodes parasites include Helicometra, Lepidapedon, and Stephanostomum species.  Other parasites that infect red grouper include the cestode Callotetrarhynchus sp., and nematodes such as Anasakis sp. (Manter 1947). 

Habitats:
Epinephelus morio is a reef-associated, non migratory species that occurs in low numbers and can be found in depths of 5 - 300m (Jory and Iversen 1989;  Heemstra and Randall 1993).  Young juveniles are commonly encountered in seagrass beds less than 15m deep (Smith 1971) in south Florida.  Older juveniles occupy shallower water in hard bottom and reef habitats approximately 36 m deep.  Immature fishes 1 – 6 years old and measuring less than 50 cm SL utilize nearshore reefs (Beaumariage and Bullock 1976).  Adults occur primarily over rocky and muddy bottoms (Fischer 1978), on limestone ledges, wrecks, and caves, but are relatively uncommon on coral reefs.  Moe (1969) reported that red grouper in the eastern Gulf of Mexico typically rest on the benthos, concealed in rocks, crevasses, or caverns, and are found from 3 – 122 m deep.

Moe (1969) summarized movements of red groupers as they age:  Early years are lived in shallow estuarine or nearshore waters 3-18m deep.  After reaching 400-450 mm SL at 4-6 years of age, they leave nearshore reefs and move to waters deeper than 36 m.  This migration apparently coincides with onset of sexual maturity.   

VI. SPECIAL STATUS

Special Status:
None.

Fisheries Importance:

          COMMERCIAL FISHERY:
The red grouper is both commercially and recreationally important throughout its range, and is one of the most abundant grouper species in southern Florida. Boats must be used by recreational anglers seeking red grouper, as they are rarely caught from beaches and docks (Jory and Iversen 1989). 

Approximately 99% of the Florida harvest of red grouper is taken in the eastern Gulf of Mexico on Florida’s west coast.  Between 1987 - 2001, the commercial harvest of red grouper in Florida totaled 95.3 million pounds, and was valued at $164.8 million.  Of this, just 628,465 pounds of red grouper, valued at $1.2 million was harvested on Florida's east coast during this time period.  Within the 5 county area encompassing the IRL (Volusia, Brevard, Indian River, St. Lucie and Martin Counties) 257,339 pounds of red grouper, 41% of the east coast total, was commercially harvested  This catch was valued at approximately $465,435, and ranks the red grouper forty-eighth  in commercial value, and sixtieth in pounds harvested. 

Figure 1 below shows the dollar value of the red grouper fishery to IRL counties by year.  The commercial red grouper fishery ranged in value from a high of $60,458 in 1995 to a low of $3,622 in 1990.  Volusia county accounted for 59% of the catch, followed by Brevard (18%), St. Lucie (10%), Martin (8%) and Indian River (5%) Counties. 

   Figure 1.  Annual dollar value of the commercial catch of red grouper to the 5-county
                area of the Indian River Lagoon. 

   Figure 2.  Total red grouper dollar value and percentage by county for the years 1987 -
                2001.

 

        Table 1.  Total dollar value of IRL red grouper, Epinephelus morio, between 1987 -
                   2001.