Freshwater Fishes of North America: Volume 1: Petromyzontidae to Catostomidae

Chapter 7 Lepisosteidae: Gars

DIVERSITY AND DISTRIBUTION The Gars inhabit waters of eastern and central North America, Meso-America, and Cuba (Figs. 7.1 and 7.2). The fossil record extends the time range of the Lepisosteidae to >100mya and extends the geographic range to western North America, Europe, Africa, India, and South America . Gars, particularly Alligator Gars, occasionally occur in coastal brackish or marine habitats, but the extant Gars are effectively freshwater fishes (Table 7.1). The same appears true for fossil Gars, which are almost entirely known from freshwater deposits (Grande 2010). The living Gars are placed in two genera: Lepisosteus with four species (Figs. 7.3 and 7.4) and Atractosteus with three species (Fig. 7.5). The extant members of Lepisosteus are restricted to eastern North America from Montana and Texas eastward. The distribution of Lepisosteus osseus (Longnose Gar, Aguja in Mexico) includes southern Quebec , Canada, south to Florida and northern Mexico, and westward from the Great Lakes region to Montana. The Longnose Gar is also referred to vernacularly as the common Gar, billfish, and needlenose Gar. Lepisosteus oculatus (Spotted Gar, Catán Pinto in Mexico) occurs from the Great Lakes south to the Gulf Coast of Texas, northern Mexico, and east to northwestern Florida. Lepisosteus platyrhincus (Florida Gar, Florida spotted Gar in earlier literature) is restricted to Florida and lowlands of southern Georgia. Lepisosteus platostomus (Shortnose Gar, vernacularly known as the duckbill garfish) occurs in lowgradient regions of the Mississippi River basin, from northeastern Texas north to Montana, east to Ohio, and south to Mississippi. Living Gars are easily identified by their torpedo-shaped bodies encased in hard, rhombohedral-shaped scales, their posteriorly set median fins, and their elongate bills lined with sharply pointed teeth. Today’s Gars (order Lepisosteiformes ) include seven species, five in eastern North America and one each in Cuba and the tropics of Central America. They are living fossils in the sense of Hubbs & Lagler (1958:30) and Wiley & Schultze (1984). That is, the family is ancient (Gars are >100 million years old), the living species show numerous primitive neopterygian traits, and the closest relatives are extinct. The living-fossil status and the air-breathing habit of Gars have generated a great deal of interest among fish systematists, developmental and evolutionary biologists, and physiologists. Gars are sometimes considered undesirable, a view fueled by their reputation for competing with and consuming more desirable gamefishes, their potential for fouling commercial fishing nets, and sometimes even the perception that the larger species pose a threat to humans (Scarnecchia 1992; Spitzer 2010). Most of the perceived problems posed by Gars are minor relative to the negative reactions they often receive from fishers and, until rather recently, most state and federal fishery management programs (Scarnecchia 1992; Spitzer 2010). Gars are now beginning to be appreciated for their own sake and as integral components of healthy aquatic ecosystems . As top predators they perform ecosystem functions that may be important in stabilizing populations of game- fish and their prey (Cross 1967; Scarnecchia 1992). At the same time, their unusual, prehistoric appearance makes Gars valued attractions at public zoos and aquaria. This is particularly true for the larger species, one of which, the Alligator Gar, Atractosteus spatula, reaches about 3m TL. Chapter 7 Lepisosteidae: Gars Anthony A. Echelle and Lance Grande 244 Genus Lepisosteus Genus Atractosteus Figure 7.2. Geographic range of Atractosteus. Figure 7.1. Geographic range of Lepisosteus. Table 7.1. Life history characteristics of Gars, Lepisosteidae. Characters Characteristics Comments Number of extant species Seven in two genera Lepisosteus, four species Atractosteus, three species Salinity preferences Fresh and brackish waters Alligator Gar occasionally in full-strength sea water Maximum size recorded in m TL Alligator Gar, 3 Females larger than males Cuban Gar, 2 Longnose Gar, 1.6 Others, 1.1–1.3 Maximum age Alligator Gar, 50 years Females live longer than males Longnose Gar, 32 years Others, 45 † Atractosteus atrox Wyoming, United States Early Eocene 52* † Atractosteus falipoui Morocco Early Cretaceous ∼100 † Atractosteus indet. sp. Alberta, Canada Late Paleocene 55 † Cuneatus cuneatus Wyoming, United States Early Eocene ∼50–55 † Cuneatus wileyi Wyoming, United States Early Eocene ∼50–55 † Masillosteus kelleri Germany Early Middle Eocene 45 † Masillosteus janeae Wyoming, United States Early Eocene 52* † Obaichthys decoratus Ceará, Brazil Early Cretaceous ∼110 † Obaichthys africanus Morocco Cretaceous ∼100 † Dentilepisosteus laevis Ceará, Brazil Early Cretaceous 110 † Dentilepisosteus(?) kemkemensis Morocco Early Cretaceous 100 * Date for Fossil Butte Member revised in Grande (2013). LEPISOSTEIDAE: GARS 249 and Florida Gars have well...