SALMONIFORM

any member of the order Salmoniformes, a diverse and complex group of fishes. The order consists of about 1,000 species in the freshwaters and in the oceans of the world. Included are the familiar trout, salmon, and pike, as well as most of the bizarre forms of fishes inhabiting the middepths of the oceans. The framework of the order Salmoniformes in the discussion below should not be considered as a definitive taxonomic category but rather as an assemblage of diverse fishes possessing several primitive anatomical features representative of an early stage in the evolution of modern bony fishes (teleostean fishes). Northern pike (Esox lucius) any member of the order Salmoniformes, a diverse group of fishes (about 1,000 species) occurring in both fresh and salt waters and including the trout, salmon, and pike (see photograph). No single characteristic distinguishes the salmoniforms from other fishes, but the small, fleshy, adipose fin found on all salmoniform fishes indicates a remote but common ancestor. This group includes some of the most valuable sporting and commercial fishes, such as the North American muskellunge , the Danube and Siberian huchen, and the Pacific king salmon. Salmoniforms are generally small, about 150 mm (6 inches) long, but the largest, the lancet fish, reaches 2.1 m (almost 7 feet). Salmoniforms have diverse swimming skills and other capabilities. Predator fish such as the trout and salmon are adapted to swift swimming and darting. Their bodies are slim and tapered, and their tails are large and serve as a rudder as well as for propulsion. Deep-sea species, however, are sedentary and scarcely swim at all; they sometimes rely on luminous bait to coax their prey within reach. The barracudinas swim in a vertical plane, darting up and down, with the head always pointing downward. A fascinating behavioral characteristic of the trout and salmon is their homing instinct. They spawn in freshwater streams and, after hatching, swim in schools to the open sea, where they may migrate for thousands of miles and generally stay from one to three years. Then, by means not fully understood, they find their way back to the spawning beds in which they were hatched. Their persistence is extraordinary; they may have to leap falls as much as 3 metres (10 feet) or more in height, but those that survive go unerringly to their natal place, there to spawn a new generation. Additional reading J.W. Jones, The Salmon (1959); W.E. Frost and M.E. Brown, The Trout (1967), two works with general information on Salmoniformes; J.E. Fitch and R.J. Lavenberg, Deep-Water Teleostean Fishes of California (1968), a book designed for the interested layman, covering many deep-sea Salmoniformes; P.H. Greenwood et al., Phyletic Studies of Teleostean Fishes with a Provisional Classification of Living Forms, Bull. Am. Mus. Nat. Hist., 131: 339455 (1966), created the order Salmoniformes; S.H. Weitzman, The Origin of the Stomiatoid Fishes with Comments on the Classification of Salmoniform Fishes, Copeia, pp. 507540 (1967), created the new suborder Osmeroidei and modified the classification of Greenwood et al. (above); R.M. McDowall, Relationships of Galaxioid Fishes with A Further Discussion of Salmoniform Classification, Copeia, pp. 796824 (1969), suggested further modifications in the classification of Salmoniformes; D.E. Rosen and C. Patterson, The Structure and Relationships of the Paracanthopterygian Fishes, Bull. Am. Mus. Nat. Hist., 141:357474 (1969), a revision of Salmoniformes with new information on early teleostean evolution; C. Patterson, Two Upper Cretaceous Salmoniform Fishes from the Lebanon, Bull. Br. Mus. Nat. Hist., Geol., 19:207296 (1970), provides new information and suggested relationships of primitive salmoniforms; W.A. Gosline, The Morphology and Systematic Position of the Alepocephaloid Fishes, Bull. Br. Mus. Nat. Hist., Zool., 18:183218 (1969), a review of the suborder Alepocephaloidei; J.G. Nielsen and V. Larsen, Synopsis of the Bathylaconidae (Pisces, Isospondyli) with a New Eastern Pacific Species, Galathea Rep., 9:221238 (1968), revises the suborder Bathylaconoidei, family Bathylaconidae in the suborder Alepocephaloidei; N.B. Marshall, Bathyorion danae, a New Genus and Species of Alepocephaliform Fishes, Dana Rep., 68:110 (1966), a technical paper on the suborder Alepocephaloidei; G.J. Nelson, Gill Arches of Some Teleostean Fishes of the Families Salangidae and Argentinidae, Jap. J. Ichthyol., 17:6166 (1970), another technical article revising the order Salmoniformes; R.J. Behnke, A New Subgenus and Species of Trout, Salmo (Platysalmo) platycephalus, from Subcentral Turkey, with Comments on the Classification of the Subfamily Salmoninae, Mitt. Hamb. Zool. Mus. Inst., 66:115 (1968), classification of trouts and salmons, and The Application of Cytogenic and Biochemical Systematics to Phylogenetic Problems in the Family Salmonidae, Trans. Am. Fish Soc., 99:237248 (1970), classification of whitefishes, subfamily Coregoninae; Stephen D. Sedgwick, The Salmon Handbook: The Life and Cultivation of Fishes of the Salmon Family (1982); Gary A. Borger, Naturals: A Guide to Food Organisms of the Trout (1980).