Muguliformes (Mullets)

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Muguliformes

(Mullets)

Class Actinopterygii

Order Mugiliformes

Number of families 1

Evolution and systematics

A revision in 1997 recognized 14 genera and 62 species of mullets as valid. Their relationships to other spiny-rayed teleosts are unclear. Skeletal features suggest affinities either to perciforms or to atherinomorphs. Morphological analyses have indicated that mugilids are part of the group Smegmamorpha, with the Synbranchiformes (swamp and spiny eels), Elassomatidae (pygmy sunfishes), Gasterosteiformes (sticklebacks, pipefishes, and relatives), and Atherinomorpha (silversides, livebearers, and relatives). Analyses of complete mitochondrial DNA sequences indicate that mugilids are related most closely to atherinomorphs and that the Synbranchiformes form the next most closely related group to the mugilids and atherinomorphs.

According to anatomical studies of the pharyngobranchial region of the head, Agonostomus is the most primitive of the mugilid genera. Joturus, Cestraeus, and Aldrichetta are, respectively, the next most derived lineages. Evolutionary relationships between the remaining, higher mullets, such as Mugil, Myxus, Liza, and Valamugil have not been resolved in published work. The oldest known mugilid fossils are skeletal remains of Mugil princeps, collected from 30- to 40-million-year-old Menilite beds of Poland and the Ukraine.

Physical characteristics

Most species commonly reach about 7.9 in (20 cm) in total length, but some (e.g., Mugil cephalus) may attain 31.5–39.4 in (80–100 cm). The head is broad and flattened dorsally in most species. The snout is short, and the mouth is small. The gill arches of many species are specialized, forming a characteristic pharyngobranchial organ that has an expanded, denticulate pad used for filtration of ingested material. In many (but not all) species of mullets, the teeth are positioned on the lips; this is unlike most species of fishes, in which teeth, if present, are attached directly to the jawbones. In most species of mullets, the teeth are very small or may even be absent.

The eyes may be partially covered by adipose tissue. There are two short, well-separated dorsal fins, the first with four spines and the second with eight to ten segmented rays. The anal fin is short, with two or three spines and seven to twelve segmented rays in adults. The pectoral fins are placed high on the body, and the caudal fin is weakly forked. The lateral line is absent. The scales are moderate to large in size, with one or more longitudinal grooves. There are two or more pyloric caeca associated with the stomach, which also has a thick-walled, muscular gizzard in most species. Mullets usually are grayish green or blue dorsally, and their flanks are silvery, often with dark longitudinal stripes. They are pale or yellowish ventrally.

Distribution

Worldwide through tropical, subtropical, and warm temperate regions; some species inhabit cool temperate waters. Several species and genera are common in the Indo-Pacific (e.g., Liza and Valamugil). Mugil generally is restricted to the Atlantic and eastern Pacific.

Habitat

Most mullets are found in coastal marine and brackish waters. They are nektonic, usually in shallow inshore environments, such as coastal bays, reef flats, tide pools, and around harbor pilings and in brackish water estuaries, lagoons, and

mangroves. They usually swim over sandy-muddy bottoms and sea grass meadows, in relatively still waters. They commonly occur at water depths of 65.6 ft (20 m) but may be found offshore or in deeper waters. Many species are euryhaline and move between marine and freshwater environments of rivers and flooded rice fields. Some species occasionally swim far upriver, and a few species spend their entire adult lives in rivers.

Behavior

Feeding behavior apparently follows daily cycles, which may change through the seasons according to water temperature and prey availability. Several species form schools, particularly at night; schooling adults may show leaping behavior, especially during the evening.

Feeding ecology and diet

Mullet fry are planktivorous; larger specimens browse on submerged surfaces and use their pharyngobranchial organ to filter particulate material, microalgae, microorganisms, and small invertebrates, such as polychaetes, crustaceans, and mollusks. Mullets are subject to predation from larger fishes (e.g., drums and basses), crocodiles, birds (in particular, pelicans), and various aquatic mammals such as seals, sea lions, and dolphins. They are also hunted by humans.

Reproductive biology

Coastal species typically spawn in shallow open areas or offshore, forming large schools before moving out to the spawning grounds. Freshwater species possibly move downstream to spawn in brackish waters; alternatively they might spawn upstream, and the fry are swept downstream for a short period before subsequently migrating back upriver.

Conservation status

One nominal species, Liza luciae, known only from the Saint Lucia estuary, Natal, is considered Endangered according to the 2002 IUCN Red List. A taxonomic revision in 1997 included Liza luciae as conspecific with the more widespread Liza melinoptera.

Significance to humans

Mullets are important food fishes, caught in subsistence and commercial fisheries, and are used in aquaculture in many parts of the world. Food and Agriculture Organization (FAO) statistics give the global commercial capture of mullets for 2000 as 409,892 metric tons (26% from China). Global aquaculture of mullets in 2000 was 100,091 metric tons (80% coming from Egypt), with a value of almost $333.4 million dollars.

Species accounts

List of Species

Mountain mullet
Fringelip mullet
Large-scale mullet
Flathead mullet
Shark mullet

Mountain mullet

Agonostomus monticola

family

Mugilidae

taxonomy

Mugil monticola Bancroft, 1834, Jamaica. Agonostomus monticola is morphologically variable. Several different species have been recognized from Central America and the West Indies, but a review in 1997 listed them as conspecific.

other common names

French: Mulet de fleuve; Spanish: Lisa de río, tepemechín.

physical characteristics

Grows to 14.2 in (36 cm) in total length. Dorsal surface of head is convex between the eyes. Teeth are small and attached directly to the jawbones. Pharyngobranchial organ is rudimentary. There are 16–23 gill rakers on the lower part of first gill arch. Anal fin has two spines and 10 soft rays in adults. There are 38–46 scales in a longitudinal series along the flanks. Body is brownish, sometimes with a silvery band on the flanks from the pectoral to the caudal fin. Dorsal, anal, and caudal fins are dusky yellowish; there is a dark spot at the base of the caudal fin.

distribution

Rivers of the West Indies, Central America, Colombia, Venezuela, and the Galapagos Islands. Occasionally reported from the rivers of Florida and Louisiana.

habitat

Freshwaters of fast-flowing hill streams.

behavior

Little is known.

feeding ecology and diet

Diet varies seasonally. Omnivorous, feeding mainly on insects, prawns, fruits, and algae.

reproductive biology

Adults may spawn in the lower reaches of rivers or in the sea. Spawning apparently correlates with peak rainfall. Larvae and juvenile fish spend perhaps six weeks at sea before migrating back upstream.

conservation status

Not threatened.

significance to humans

There are small commercial and subsistence fisheries in the West Indies and Central America.

Fringelip mullet

Crenimugil crenilabis

family

Mugilidae

taxonomy

Mugil crenilabis Forsskal, 1775, Red Sea.

other common names

French: Mulet boxeur; Spanish: Lisa labride.

physical characteristics

Commonly reaches 10.2 in (26 cm) in standard length but may reach 19.7 in (50 cm). The upper lip is very thick, with up to 10 rows of small papillae in fish larger than 2.4 in (6 cm). There are no teeth on the lips. The anal fin has three spines and usually nine soft rays in adults. There are 36–42 scales in a longitudinal series along the flanks. Body is olive-green dorsally and silvery on the flanks and abdomen. Pectoral fins are yellowish, with a distinct dark purplish spot at the upper part of the fin base.

distribution

Indo-Pacific, from the Red Sea to Polynesia.

habitat

In shallow waters (up to 65.6 ft, or 20 m) of lagoons with sandy and muddy bottoms, reef flats, tide pools, and harbors.

behavior

Little is known.

feeding ecology and diet

Larvae and juveniles probably feed on plankton. Adults probably feed on particulate organic material, algae, and invertebrates.

reproductive biology

Adult fish form schools in shallow waters around lagoons before spawning.

conservation status

Not threatened.

significance to humans

Small commercial and subsistence fisheries, particularly in Polynesia; some aquaculture.

Large-scale mullet

Liza grandisquamis

family

Mugilidae

taxonomy

Mugil grandisquamis Valenciennes, 1836, Gorée, Senegal.

other common names

French: Mulet écailleux; Spanish: Liza escamuda.

physical characteristics

Commonly reaches 9.8 in (25 cm) in standard length but may reach up to 15.7 in (40 cm) in fork length. Teeth on both lips are absent or are very small, well spaced, and positioned in a single row on the upper lip, or rarely, in two rows. The anal fin has three spines and nine soft rays in adults. There are 26–30 scales in a longitudinal series along the flanks. Body is darkish dorsally and slightly paler and silvery laterally and ventrally. The anal fin and lower lobe of the caudal fin may be yellowish.

distribution

West Africa from Senegal to the Republic of Congo.

habitat

Usually found in brackish waters covering muddy substrates, such as mangroves, creeks, estuaries, and inundated mudflats.

behavior

Little is known.

feeding ecology and diet

Adults feed in schools, mostly at night, on particulate organic matter, mud, diatoms, algae, microarthropods, foraminiferans,

and free-living nematodes. During the wet season fish take a greater proportion of fine organic material than coarser sands, because increased rainfall brings more fine allochthonous material into rivers and "washes" the sand sediments free of fine food material.

reproductive biology

Populations from the Ebrie lagoon, Ivory Coast, do not show a seasonal spawning cycle; spawning occurs principally in the lagoon but also may occur in the sea.

conservation status

Not threatened.

significance to humans

Small commercial and subsistence fisheries. A potentially important species for aquaculture.

Flathead mullet

Mugil cephalus

family

Mugilidae

taxonomy

Mugil cephalus Linnaeus, 1758, European seas. It has been suggested that several species, initially distinguished by slight differences in morphological features, fin ray counts, dentition, and fin coloration, are synonymous with Mugil cephalus. Some authors have indicated that the concept of Mugil cephalus as a widespread, polymorphic species may be incorrect. According to comparative analyses of the morphometrics, isozymes, and mitochondrial DNA of populations of Mugil cephalus from around the world, however, the variation between populations is not large enough to indicate definitively that they are differentiated species.

other common names

English: Striped mullet, black mullet; French: Mulet cabot; Spanish: Lisa pardete.

physical characteristics

Commonly reaches 13.8 in (35 cm) in total length but may reach 47.2 in (120 cm) in standard length. Adipose tissue covers most of the eye. There are several rows of very small unicuspid and bicuspid teeth on the edges of the lips. Anal fin has three spines and eight soft rays in adults. There are 36–44 scales in a longitudinal series along the flanks. Body is olive-green dorsally and silvery on the flanks and abdomen, with about seven longitudinal dark stripes along the flanks. The pelvic fin, anal fin, and lower lobe of the caudal fin are yellowish in some populations.

distribution

Worldwide in tropical, subtropical, and warm temperate waters from 42° S latitude to almost 51° N latitude; less abundant in the tropics.

habitat

Tolerant of salinity levels from zero to 81 parts per thousand (freshwater to hypersaline) and temperatures from 41°F (5°C) to 98.6°F (37°C). Inhabits inshore marine waters, estuaries, lagoons, and rivers, usually in shallow waters, and rarely moving deeper than 656 ft (200 m). Adults may move far upriver.

behavior

The adults form schools and sometimes jump.

feeding ecology and diet

Larvae and juveniles feed on plankton. Adults feed on particulate organic material, algae, and invertebrates. Fish may gulp and filter sediment, browse over submerged surfaces, or feed at the surface.

reproductive biology

Adult fish move offshore in shoals to spawn, usually at night, before returning to inshore brackish waters and freshwaters. Fry and juveniles remain in sheltered bays, lagoons, and estuaries until they are sexually mature.

conservation status

Not threatened.

significance to humans

Major commerical and subsistence fisheries in many parts of the world. Food and Agriculture Organization (FAO) of the United Nations statistics give the global commercial capture of flathead mullets for 2000 as 29,335 metric tons (18% and 19% coming from Mexico and Venezuela, respectively). Global aquaculture of flathead mullets in 2000 was 89,078 metric tons (90% coming from Egypt), with a value of almost $312.3 million dollars.

Shark mullet

Rhinomugil nasutus

family

Mugilidae

taxonomy

Mugil nasutus De Vis, 1883, Cardwell, Rockingham Bay, Queensland, Australia.

other common names

English: Mud mullet.

physical characteristics

Reaches 12.6 in (32 cm) in fork length. The shark mullet looks unlike other mullets, because the eyes are positioned high, toward the top of the head, which is concave between the eyes. Nostrils are placed low on the snout, which projects beyond the upper lip. Teeth on both lips are small and spatulate. The anal fin has three spines and eight soft rays in adults. There are 28–30 scales in a longitudinal series along flanks. Body is slate gray dorsally and silvery laterally and ventrally; the fins are yellowish.

distribution

Tropical Australia and New Guinea.

habitat

Usually occurs in muddy freshwaters and coastal water habitats, such as mangroves.

behavior

Swims in schools at the water surface, with the eyes and snout exposed. Apparently capable of breathing air and wriggling for short distances over mud banks.

feeding ecology and diet

Feeds on muddy substrates and may feed on algae and insects at the water surface.

reproductive biology

Little is known.

conservation status

Not threatened.

significance to humans

No reported fisheries data. Species of Rhinomugil (usually Rhinomugil corsula) are sold in the aquarium trade, because of their similarity to species of four-eyed fish (Anableps).

Resources

Books

De Sylva, D. P. "Mugiloidei: Development and Relationships." In Ontogeny and Systematics of Fishes, edited by H. G. Moser, W. J. Richards, D. M. Cohen, M. P. Fahay, A. W. Kendall, Jr., and S. L. Richardson. Lawrence, KS: American Society of Ichthyologists and Herpetologists, 1984.

Harrison, I. J. "Mugilidae." In Guía FAO para la Identificacíon de Especies para los Fines de la Pesca Pacifico Centro-Oriental, edited by W. Fischer, F. Krupp, W. Schneider, C. Sommer, K. E. Carpenter, and V. H. Niem. Vol. 3. Rome: FAO, 1995.

Harrison, I. J., and H. Senou. "Mugilidae." In FAO Species Identification Guide for Fisheries Purposes. The Living Marine Resources of the Western Central Pacific, Vol. 4. Bony Fishes, Part 2, (Mugilidae to Carangidae), edited by K. Carpenter and V. H. Niem. Rome: FAO, 1999.

Nelson, J. S. Fishes of the World. 3rd edition. New York: John Wiley and Sons, 1994.

Oren, O. H. Aquaculture of Grey Mullets. International Biological Programme vol. 26. Cambridge: Cambridge University Press, 1981.

Patterson, C. "Osteichthyes: Teleostei." In The Fossil Record, edited by M. J. Benton. Vol. 2. London: Chapman and Hall, 1993.

Smith, M. M., and J. L. B. Smith. "Mugilidae." In Smiths' Sea Fishes, edited by M. M. Smith and P. C. Heemstra. Berlin: Springer-Verlag, 1986.

Periodicals

Albaret, J.-J., and M. Legendre. "Biologie et Ecologie des Mugilidae en Lagune Ebrié (Côte d'Ivoire): Intérét Potential pour l'Aquaculture Lagunaire." Revue d'Hydrobiologie Tropicale 18, no. 4 (1985): 281–303.

Blaber, S. J. M., and A. K. Whitfield. "The Feeding Ecology of Juvenile Mullet (Mugilidae) in South-east African Estuaries." Biological Journal of the Linnean Society 9 (1977): 277–284.

Corti, M., and D. Crosetti. "Geographical Variation in the Grey Mullet: A Geometric Morphometric Analysis Using Partial Warp Scores." Journal of Fish Biology 48 (1996): 255–269.

Crosetti, D., W. S. Nelson, and J. C. Avise. "Pronounced Genetic Structure of Mitochondrial DNA Among Populations of the Circumglobally Distributed Grey Mullet (Mugil cephalus Linnaeus)." Journal of Fish Biology 44 (1994): 47–58.

Cruz, G. A. "Reproductive Biology and Feeding Habits of Cuyamel, Joturus pichardi, and Tepemechín, Agonostomus monticola (Pisces; Mugilidae), from Río Platano, Mosquitia, Honduras." Bulletin of Marine Science 40, no. 1 (1987): 63–72.

De Silva, S. S. "Biology of Juvenile Grey Mullet: A Short Review." Aquaculture 19 (1980): 21–36.

Drake, P., A. M. Arias, and L. Gallego. "Biología de los Mugílidos (Osteichthyes, Mugilidae) en los Esteros de las Salinas de San Fernando (Cádiz). III. Hábitos Alimentarios y su Relación con la Morfometría del Aparato Digestivo." Investigacion Pesquera 48, no. 2 (1984): 337–367.

Harrison, I. J., and G. J. Howes. "The Pharyngobranchial Organ of Mugilid Fishes: Its Structure, Variability, Ontogeny, Possible Function and Taxonomic Utility." Bulletin of the British Museum of Natural History (Zoology Series) 57, no. 2 (1991): 111–132.

Johnson, G. D., and C. Patterson. "Percomorph Phylogeny: A Survey of Acanthomorphs and a New Proposal." Bulletin of Marine Science 2, no. 1 (1993): 554–626.

King, R. P. "Observations on Liza grandisquamis (Pisces: Mugilidae) in Bonny River, Nigeria." Revue d'Hydrobiologie Tropicale 19, no. 1 (1986): 61–66.

——. "New Observations on the Trophic Ecology of Liza grandisquamis (Valenciennes, 1836) (Pisces: Mugilidae) in the Bonny River, Niger Delta, Nigeria." Cybium 12, no. 1(1988): 23–36.

Miya, M., A. Kawaguchi, and M. Nishida. "Mitogenomic Exploration of Higher Teleostean Phylogenies: A Case Study for Moderate-Scale Evolutionary Genomics with 38 Newly Determined Complete Mitochondrial DNA Sequences." Molecular Biology and Evolution 18, no. 11(2001): 1993–2009.

Phillip, D. A. T. "Reproduction and Feeding of the Mountain Mullet, Agonostomus monticola, in Trinidad, West Indies." Environmental Biology of Fishes 37 (1993): 47–55.

Senou, H. "Redescription of a Mullet, Chelon melinopterus (Perciformes: Mugilidae)." Bulletin of the Kanagawa Prefectural Museum of Natural Sciences 26 (1997): 51–55.

Stiassny, M. L. J. "What Are Grey Mullets?" Bulletin of Marine Science 52, no. 1 (1993): 197–219.

Thomson, J. M. "The Mugilidae of the World." Memoirs of the Queensland Museum 41, no. 3 (1997): 457–562.

Torres-Navarro, C. I., and J. Lyons. "Diet of Agonostomus monticola (Pisces: Mugilidae) in the Río Ayuquila, Sierra de Manantlán Biosphere Reserve, México." Revista de Biología Tropical 47, no. 4 (1999): 1087–1092.