(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
Mountain mulletFringelip mullet
Large-scale mullet
Flathead mullet
Shark mullet
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.
Other:Food and Agriculture Organization of the United Nations. "Fishery Software." (12 Feb. 2003).
[Article by: Ian J. Harrison, PhD]
