Species Profile Mutton Snapper

SRAC Publication No. 725 VI May 2001 PR Species Profile Mutton Snapper Wade O. Watanabe1 Snappers (class Osteichthyes; order Perciformes; family Lutjanidae) are important commercial and recreational food fish species throughout tropical areas of the world. In the western Atlantic, lutjanids are rep- resented by 18 species in five gen- era: Apsilus, Etelis, Pristopomoides, Rhomboplites and Lutjanus. The mutton snapper (Lutjanus analis; Fig. 1) is one of 12 species in the genus Lutjanus. Snappers are popular food fish and demand for them is increasing, as evidenced by burgeoning imports of several snapper species. The demand, and the relatively high Figure 1. Adult mutton snapper, Lutjanus analis. (photo by C. Manfredi) value of snappers, make them inter- esting to aquaculturists. Color and pigmentation this spot is much larger, and the lat- Identifying characteristics eral line passes through its lower Young mutton snapper are olive half. Two other inshore lutjanid Most of the Bahamian species of green with broad, indistinct vertical species have black spots in the sub- Lutjanus have rounded anal-fin bars on the body. The dorsal and dorsal area, the lane snapper, L. lobes; only mutton snapper and the anal fins are reddish, and there is a synagris, and the mahogany snap- deeper water silk snapper blue stripe below the eye. Young per, L. mahogoni. These species usu- (L. vivanus) have pointed anal-fin mutton snapper are sleek, whereas ally have 12 segmented dorsal-fin lobes. The mutton snapper has a the adults develop a high back. rays, while the mutton snapper chevron-shaped vomerine tooth Adult body color varies consider- usually has 14. The mutton snapper patch on the upper palate without a ably from white to red. Some closely resembles L. mahogoni, but is posterior extension, whereas the silk appear olive above the lateral line distinguishable by the rows of snapper has a posterior extension of and white with a reddish hue bluish dots near the eye, which L. the patch. The mutton snapper is a below. The anal and ventral fins mahogoni lacks. Mutton snapper medium-sized fish, usually about 50 and the lower half of the caudal fin have both plain and barred color cm (19.7 inches) long. It can grow as are reddish and there are blue lines phases (Fig. 2). The fish usually is long as 82.4 cm (32 inches) and and dots below, before and behind barred when feeding on the bot- weigh more than 11.4 kg (25 the eye. Adults have a very small tom, when at rest, or during pounds). subdorsal body spot about the same encounters with other fishes; it size as the pupil and situated above becomes nearly uniform in color the lateral line below the anterior 1The University of North Carolina at when swimming. Wilmington, Center for Marine Science end of the soft dorsal fin. In young, Food habits and feeding feeding behavior according to fish behavior size and time of day may reduce intraspecific competition. Snappers are generally nocturnal predators. During the day they Growth rates and length-weight form inactive schools in which relationships dominance relationships and intraspecific aggression are rarely A theoretical growth curve for mut- observed. The mutton snapper may ton snapper (Fig. 3) from juvenile be atypical of snappers in general, through adult stages was generated because observations of a shallow by measuring fish of various ages water population ranging from 6 to sampled from headboat landings 25.6 inches (15 to 65 cm) in fork from Jacksonville Beach, Florida to length (FL) in the Bahamas revealed Key West from 1976 to 1981 (Mason that the fish formed dominance and Manooch, 1985). In wild popu- hierarchies and fed diurnally. A car- lations, growth in length is relative- nivorous species, the mutton snap- ly fast for the first 2 years, but per feeds on fishes, particularly drops sharply in the third year and small grunts (family Pomadasyi- declines slowly thereafter. Annual dae), and nocturnally active crus- growth increments were 6.3 and 5.4 taceans. Mutton snapper feed pri- inches (161 and 137 mm) for ages-1 marily by picking prey organisms and -2, but only 3.5 inches (90 mm) from the surface of the substrate. for age-3, and 57 mm for age-4 fish.1 They feed during all times of day. Growth in weight (Fig. 3) was Winnowing (the separation of prey determined from the length- weight from substrate) occurs during mid- relationship, W = 1.0 x 10-8TL3.0499, day and evening, whereas midwa- where W = weight in kg and TL = ter strikes are confined to morning total length in mm. Growth in and evening. When feeding on the weight is fastest between ages 5 and substrate the fish have dark, barred 10 years. The oldest fish examined color patterns, whereas no color was 14 years; it measured 32.4 inch- Figure 2. Color patterns in mutton snapper changes occur during midwater es (824 mm). Longevity was esti- associated with intraspecific displacing strikes. Small fish less than 1 year mated at 15 to 20 years. The rela- and feeding events (Mueller, et al., 1994). old feed more often than medium- tionships between total length (TL), Normal (a), dark barred (b, c), and dark sized or large fish during daylight fork length (FL), and standard nape (d) color patterns are transient. hours and have very few encounters with other mutton snapper. Natural History 1Age-1, -2, etc. refers to age during yearly This suggests that small fish chan- intervals. Age-0 fish are between birth and Geographic range nel most of their energy toward 1 year of age, age-1 fish are between 1 and feeding and growth. Differences in 2 years old, etc. The mutton snapper inhabits warm, temperate and tropical waters of the western Atlantic, with distribu- 7000 tion ranging from New England to 800 southeastern Brazil, including the Bahamas and Gulf of Mexico. 6000 700 Mutton snapper are most abundant in the waters around southern 5000 600 Florida, the Bahamas and the Antilles. 500 4000 Habitat 400 Mutton snapper are found in vari- 3000 Body weight (g) Body weight ous habitats. Juveniles and small 300 length (mm) Total adults are found in shallow coastal 2000 waters over coral reefs, in protected Body weight 200 bays with grass beds or mud bot- Total length 1000 toms, in tidal creeks surrounded by 100 mangrove, and in canals. Larger adults are found in deeper waters 0 0 on the continental shelf out to 91- 1234567891011121314 foot (28-m) depths. Age (year) Figure 3. Theoretical growth curves for wild populations of mutton snapper based on fishery samples (Mason and Manooch, 1985). length (SL), based on wild-caught and adults suggest that the young Induced spawning specimens, were described as fol- recruit into shallow inshore waters, lows: SL = - 0.2 + 0.85 FL, and TL = gradually moving into deeper off- Hormone-induced spawning of a 0.7 + 1.09 FL. shore areas with maturity. Large captive mutton snapper broodstock fish roam greater distances, where- was first reported by Watanabe et Reproduction and spawning as small individuals remain close to al. (1998). In this study, wild-caught shelter. Recruitment of juveniles subadults were reared under ambi- Large spawning aggregations of ent photoperiod and temperature in (< 7 cm fork length) to seagrass 3 mutton snapper occur seasonally beds in Florida and Cuba has been outdoor, 15-m , flow-through sea- off the coasts of Cuba, the Turks reported to peak during August water (36 to 38 ppt) tanks. Fish and Caicos, and the U.S. Virgin and September. From hatchery were fed frozen squid and a com- Islands. In the continental U.S., the observations, sexual maturity mercially prepared striped bass diet last known spawning aggregation appears to occur at the age of 3 containing 38 percent protein. of mutton snapper is located in the years and at a size of 18 to 18.5 During their third year in captivity Riley’s Hump near the Dry inches (45.5 to 47.0 cm) total length fish reached first maturity and were Tortugas area off Key West, Florida. and 3.5 to 4.5 pounds (1.58 to 2.04 induced to spawn by hormone May and June are the principal kg) in females, and 14.8 to 18.3 treatment. A female (1.79 kg; 46 cm spawning months for mutton snap- inches (37.5 to 46.5 cm) total length FL) with mature, vitellogenic-stage per populations in this aggregation, and 3.7 to 4.0 pounds (1.69 to 1.83 oocytes with a mean oocyte diame- which is heavily fished by commer- kg) in males. This is consistent with ter of 382 µm (range = 225 to 475 cial and recreational anglers. data from fishery samples. µm and a unimodal egg diameter- Captive, wild-caught broodstock frequency distribution) was held in outdoor tanks under ambi- Culture Techniques induced to spawn by injection of ent photo-thermal conditions in the the mammalian hormone human central Bahamas matured and Broodstock procurement chorionic gonadotropin (HCG). spawned in association with Two intramuscular injections were Mutton snapper broodstock are increasing photoperiod and water used: a first (priming) dose of 500 generally caught by hook-and-line temperature conditions in the IU/kg body weight was followed or by traps from spawning aggre- spring and early summer. 24 hours later by a second (resolv- gations off the Florida Keys, ing) dose of 1,000 IU/kg body It is known, however, that repro- although specimens have been weight. At the time of the second ductive seasonality in a given lut- obtained from the Indian River injection, three males also were janid species may vary among pop- Lagoon Estuary in Florida.

Load more