Canals as Vectors for Fish Movement: Potential Southward
Range Expansion of Lepisosteus osseus L. (Longnose Gar)
in South Florida
David A. Gandy, Jennifer S. Rehage, Jay W. Munyon, Kelly B. Gestring,
and John I. Galvez
Southeastern Naturalist, Volume 11, Issue 2 (2012): 253–262
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2012 SOUTHEASTERN NATURALIST 11(2):253–262
Canals as Vectors for Fish Movement: Potential Southward
Range Expansion of Lepisosteus osseus L. (Longnose Gar)
in South Florida
David A. Gandy1,*, Jennifer S. Rehage1, Jay W. Munyon2, Kelly B. Gestring3,
and John I. Galvez4
Abstract - Lepisosteus osseus (Longnose Gar) is a large-bodied predator, whose Florida
distribution remains unclear at the southern edge of its range. We reviewed available
literature and museum voucher specimens to provide a more accurate range description,
and we discuss recent collections in south Florida. Longnose Gar has not been previously
reported in natural habitats south of Lake Okeechobee. Instead, records south of the lake
are from canals, and most are recent (since 2000), including our own southernmost 2011
record. No records from Everglades natural habitats have been collected. Previous studies
have shown native range expansions in anthropogenically disturbed landscapes. We
suggest that the Longnose Gar is expanding its range southward in Florida using canals
as dispersal vectors and/or suitable habitat.
Lepisosteus osseus L. (Longnose Gar) is one of seven extant species in the fish
family Lepisosteidae. Longnose Gar has anatomically distinct characteristics—
primarily its thin, elongate snout, which more than doubles head length and
is significantly longer than that of close relatives (Suttkus 1963)—that easily
distinguish it from other Lepisosteids. Aside from snout length, a single row of
sharp villiform teeth in the upper jaw allows this species to be easily distinguishable
from Atractosteus spatula Lacepede (Alligator Gar; Page and Burr 1991).
The coloration of Longnose Gar is olivaceous brown dorsally and into the sides,
fading to a pale yellow or white ventrally (Becker 1983, Suttkus 1963). Young
have a pronounced broad, dark mid-lateral stripe that runs from the snout to the
base of the caudal fin with a distinct white stripe directly below it (Becker 1983,
Smith 2002). Coloration varies in relation to water clarity; dark spots on unpaired
fins extending into the body and the dorsal region of the head in clear water, and
a deeper green coloration with stronger brown hues in murky waters (Suttkus
1963). Longnose Gar is more common in freshwater, although individuals have
been caught at salinities as high as 33 psu (Goodyear 1967, Hildebrand and
Schroeder 1928, Jean 1946, Schwartz 2003, Swift et al. 1977).
Once geographically widespread, fossils of all seven extant species of gar have
been found throughout North America, Europe, Africa, and Asia, and date to the
lower Cretaceous period (Helfman et al. 2009, Stiassny et al. 2004, Wiley 1976).
1Earth and Environment Department, Southeast Environmental Research Center, Florida
International University, Miami, fl33199. 2Department of Biological Sciences, Florida
International University, Miami, fl33199. 3Non-Native Fish Laboratory, Florida Fish
and Wildlife Conservation Commission, Boca Raton, fl33431. 4 US Fish and Wildlife
Service, Peninsular Florida Fish and Wildlife Conservation Office, Vero Beach, FL
32960. *Corresponding author - firstname.lastname@example.org.
254 Southeastern Naturalist Vol. 11, No. 2
However, its present-day range is considerably narrower, extending from Quebec
to Florida, into the Mississippi and Rio Grande drainages (Hubbs et al. 2008, Page
and Burr 1991). In Florida, the delineation of its distribution is somewhat unclear.
Some authors have described Longnose Gar’s distribution to be statewide (Briggs
1958, Carr and Goin 1955, Stevenson 1976), while others suggest a southern
boundary. Kilby and Caldwell (1955) conducted the first survey of fishes in south
Florida, and considered Lake Okeechobee to be the southern end of its range. Ager
(1971) also reported Longnose Gar in Lake Okeechobee, while Lee et al. (1980)
mapped a central Florida boundary and vaguely stated its distribution as “Florida”,
and Page and Burr (1991) delineated its range as “central Florida”.
To clarify the natural range of Longnose Gar in Florida, particularly along the
southern boundary of its distribution, we compiled available records of its occurrence
in natural habitats from the published and available grey literature and
from museum voucher specimens. By natural habitats, we refer to lakes, ponds,
rivers, wetlands, and estuaries, but exclude artificial habitats such as canals.
We also noted icthyofaunal studies that report no observations or collections of
this species. Lastly, we highlight recent records of this species south of Lake
Okeechobee, all from canals, including the southernmost record to date, which
is from our own sampling. Our objectives were to (1) clarify the native range
distribution of Longnose Gar in natural waters of Florida, and (2) discuss the possibility
that the Longnose Gar is undergoing a recent southern range expansion in
the Everglades region, facilitated by canals.
Our literature review yielded 15 studies (1935–1990) showing 32 records
of Longnose Gar from nine of the 14 major Florida drainages excluding south
Florida (Table 1). We complemented the literature findings with over 160 museum
voucher specimens (1948–2009) obtained from the Florida Museum of
Natural History and the Fish and Wildlife Conservation Commission’s Fish and
Wildlife Research Institute. We plotted these records, which span the past 74
years, using ArcGIS 9 (Fig. 1). For the museum specimens, we plotted only those
that constituted new locations from those already reported in the field studies,
totaling 37 additional records (Fig. 1). To explore the possibility of a southward
range expansion of Longnose Gar, we then noted at least 17 observations reported
from the Everglades region, beginning with the first reports by Dineen (1974)
(Table 2). These new records include the southernmost record to date, in western
Miami-Dade County, from our own monitoring efforts of fishes in canals bordering
Everglades National Park (ENP). Similarly, we used ArcGIS 9 to map these
new south Florida records (Fig. 2).
Results and Discussion
Our review indicates that the Longnose Gar occurs naturally throughout Florida,
extending as far south as Lake Okeechobee and the Loxahatchee River, but we found
no records from natural habitats in the extreme southern part of Florida, including
the Everglades (Table 1, Fig. 1). Four studies indicated that Longnose Gar commonly
occur throughout the Florida panhandle (Table 1, Fig. 1), whereas 11 studies
2012 D.A. Gandy, J.S. Rehage, J.W. Munyon, K.B. Gestring, and J.I. Galvez 255
describe their occurrence in water bodies spanning from the St. Johns and southward
to the Peace and Kissimmee drainage basins. The voucher specimens contributed records
for an additional two drainages (Aucilla-Waccasassa and East Coastal) along
the coastal panhandle and the Atlantic coastal region of central Florida.
For the Greater Everglades region, we examined 20 fish studies south of
Lake Okeechobee conducted between 1955 and 2011, none of which reported
Longnose Gar occurrences from natural habitats (Table 1, Fig. 1). Collectively,
Table 1. Summary of 35 studies noting the occurrence or absence of L. osseus in Florida. All of
these studies are shown in Figure 1. For habitat type: E = estuarine, C = canal, CC = coastal creeks,
L = lake, M = marsh, P = pond, R = river, S = spring. For notes on occurrence: O = observed, C =
collected, NS = not specified, A = not observed or collected. For sampling gear: A = angling, D =
drop trap, E = electrofishing, EG = entanglement gear, O = other, R = rotenone, SP = spear fishing,
T = throw trap, V = visual.
Source Habitat type Drainage basin Occurrence gear
Goff 1935 L St. Johns O O
Fowler 1940 L St. Johns O V
Hubbs and Allen 1943 S St. Johns C SP
Allen 1946 S St. Johns O, C V
Herald and Strickland 1949 R, S Tampa O O
Moody 1954 L Tampa, St. Johns C EG
Holloway 1954 L, R St. Johns C SP
McLane 1955 R St. Johns O, C EG, O
Hellier 1967 R Suwannee O, C EG, O
Tagatz 1967 R St. Johns NS EG
Ager 1971 L Kissimmee C EG
Beecher et al. 1977 R Escambia O, C E, EG
Swift et al. 1977 R, E Ochlockonee C EG, O
Beecher and Hixson 1982 R Choctawhatchee, O, C E
Champeau 1990 R Peace O, C E
Kilby and Caldwell 1955 M, C South Florida A O
Kahl 1964 M South Florida A EG, O
Kushlan 1972 M South Florida A O
Kushlan and Lodge 1974 M, C South Florida A O
Kushlan 1976 M South Florida A O
Carlson and Duever 1977 M South Florida A O
Loftus and Kushlan 1987 M, R, C South Florida A A, E, EG, O, R, T
Lorenz et al. 1997 M, E South Florida A D
Fury et al. 1995 M, C South Florida A EG
Trexler et al. 2001 M, C South Florida A E, T
Chick et al. 2004 M South Florida A E
Ellis et al. 2003 M, R, P, C South Florida A E, EG, O, V
Trexler et al. 2005 M South Florida A T
Ruetz et al. 2005 M South Florida A T
Kline and Bamford 2006 M, C South Florida A O, T
Lorenz and Serafy 2006 M, E South Florida A D
Rehage and Trexler 2006 M South Florida A E, T
Rehage and Loftus 2007 HC South Florida A E
Kline and Fratto 2008 M, C South Florida A O, T
Parkos et al. 2011 M South Florida A E
256 Southeastern Naturalist Vol. 11, No. 2
these studies surveyed wide expanses of the Greater Everglades region, from
the water conservation areas (WCAs), south to ENP, and stretching into the
marsh-mangrove ecotone (Table 1, Fig. 1). The studies used different sampling
techniques and targeted a variety of habitats, including freshwater marshes,
coastal mangroves, alligator holes, and ponds. Additionally, eight of those studies
also surveyed canals but reported no records (Table 1). Similarly, a number
of studies by P. Shafland (Non-Native Fish Laboratory, Florida Fish and Wildlife
Conservation Commission, Boca Raton, FL) conducted between 1975–2008
largely in canals, reported no occurrences over this period (e.g., Shafland et al.
2008). Loftus and Kushlan (1987) sampled 181 sites encompassing a range of
freshwater and coastal habitats in urban Miami and the southern Everglades and
noted Longnose Gar to be a species of “doubtful occurrence” that had not been
collected in extreme southern Florida.
In contrast, recent records indicate that Longnose Gar is in fact present in south
Florida, but appear confined to canal habitats (Table 2, Fig. 2). We report 12 observations
(totaling at least 17 fish) beginning with several specimens reported in
1974, and a number of recent observations since 2000, which include one museum
specimen (Table 2, Fig. 2). Dineen (1974) collected the species in the northern
Everglades as part of a 12-year monitoring project (1962–1974) conducted by the
Florida Game and Freshwater Fish Commission. He reported several Longnose
Gar collected from the south side of the L-39 canal in northern WCA 2A in 1965
(collected via rotenone and netting), and noted one other specimen caught by an
Figure 1. Map of the State of Florida showing presence or absence of L. osseus in natural
habitats (e.g., marshes, rivers, lakes). Presence studies are from 1935 to 1990, while absence
studies date from between 1950 to 2011 (see Table 1). Museum voucher specimens
are shown in grey symbols (37 records), while field studies are shown in black symbols
2012 D.A. Gandy, J.S. Rehage, J.W. Munyon, K.B. Gestring, and J.I. Galvez 257
angler in 1972 from the L-39B canal (Fig. 2). The remaining 15 specimens collected
or observed between 2000 and 2011 are also exclusively from Everglades
or urban canals. This includes the southernmost record to date (one specimen, 118
cm TL), collected in November 2011 from the L-31W canal via boat-mounted electrofi
shing (Table 2, Fig. 2). Interestingly, most records are of adults (80–118 cm
TL), whereas the five juvenile records (41–47.5 cm TL) are from the L-40 and L-7
canals (closer to Lake Okeechobee than all adult records).
These new records south of Lake Okeechobee suggest a southern range
expansion for Longnose Gar into south Florida. Its presence in south Florida exclusively
in a large, interconnected network of canals indicates that canals may
be serving as conduits for its dispersal, and/or suitable habitat for this species
since no specimens have been collected in natural Everglades marshes or other
deep-water habitats. Elsewhere, Longnose Gar is commonly observed over a
range of low to moderate flow conditions and salinities, and is more commonly
Figure 2. Map of south Florida showing new occurrences of L. osseus from 1974 to 2011
in canals both in the Everglades region and urbanized south Florida (see Table 2).
258 Southeastern Naturalist Vol. 11, No. 2
found in deep and structurally complex portions of lakes and river channels
(McGrath 2010, Suttkus 1963). Robertson et al. (2008) examined the association
between hydrologic connectivity and habitat partitioning among three gar species
in a Texas river, and found that 84% of Longnose Gar were captured in the river
channel rather than in shallower, associated oxbows.
Relatively little is known about the movement or home range of this species,
except for migratory movements during the reproductive season. Johnson and
Noltie (1996) found that resident lake Longnose Gar move into stream tributaries
to spawn, and reported post-spawning recaptures as far as 48 km away
from spawning grounds. Spawning migrations of Longnose Gar were positively
correlated to stream flow, and individuals exhibited high annual site fidelity to
spawning grounds. In our canals, the majority of records are adults; thus, it remains
unclear whether the use of canals is related to spawning. The exact source
population for this range expansion is not known, but we hypothesized that
movement out of Lake Okeechobee, or via the lake from other water bodies, is
most likely because of its connectivity to south Florida’s canal network.
The modern Everglades canals date back to the 1880s, and currently amount to
2500 km of canals and levees that compartmentalize the system, disrupting sheet
flow and hydrologic connectivity (Light and Dineen 1994, Sklar et al. 2002).
Canals in the system play a number of roles, by acting as sources of nutrients,
pollutants, and non-native species (Harvey et al. 2010). From a biotic standpoint,
their role as thermal refugia for non-native fishes is of importance, and likely a
key factor in the persistence of non-native populations (Schofield et al. 2010,
Trexler et al. 2001). Canals may also provide permanent deep-water refuge for
biota that were historically rare or absent in the ecosystem (Gunderson and Loftus
1993), and whose habitat quality is unknown. Their role as dispersal vectors,
Table 2. Summary of new records of L. osseus in south Florida in artificial canals, 1974–2011, also
mapped in Figure 2. For occurrence (occur.): A = caught by recreational angler, C = collected, O =
observed, NS = not specified and number in parenthesis refers to the number of specimens reported.
For sampling gear type: A = angling, E = electrofishing, EG = entanglement gear, R = rotenone.
Water body Rec. # Yr Northing Easting Occur. gear Source
L-35B Canal 1 1974 2895649 555367 A (1) A Dineen 1974
L-39 Canal 1 1974 2916862 564586 C (NS) EG, R Dineen 1974
N New River Canal (G-15) 2 2000 2889937 563592 C (3) E This study
W Palm Beach Canal (C-51) 3 2006 2947448 593424 C (1) E This study
Hillsboro Canal (G-08) 4 2007 2913997 574002 C (2) E This study
L-67 Ext. Canal 5 2009 2844965 532847 C (1) E Museum specimen*
C-1W 6 2010 2828223 562775 O (1) E This study
L-30 Canal 7 2011 2851843 551886 A (1) A This study
L-31W Canal† 8 2011 2816214 542367 C (1) E This study
L-7 Canal 9 2011 2949185 560630 C (2) E This study
L-7 Canal 10 2011 2944924 557692 C (1) E This study
L-7 Canal 11 2011 2941148 555308 C (1) E This study
L-40 Canal 12 2011 2942696 571439 C (1) E This study
†Denotes the southernmost and most recent record in southern Miami-Dade County.
*Denotes a voucher specimen provided by University of Florida, Florida Museum of Natural History,
Division of Ichthyology, Gainesville, FL; collected by J. Kline; and deposited by L.M. Page.
2012 D.A. Gandy, J.S. Rehage, J.W. Munyon, K.B. Gestring, and J.I. Galvez 259
suitable year-around deep habitats, and as corridors for range expansion of native
fishes has been previously noted (Ellis et al. 2003, Harvey et al. 2010, Loftus and
Kushlan 1987). Loftus and Kushlan (1987) found that Esox niger Lesueur (Chain
Pickerel), Ictalurus punctatus Rafinesque (Channel Catfish), and Pomoxis nigromaculatus
Lesueur (Black Crappie) were widely distributed in central Florida,
but were common in south Florida only in canals. We can now add Longnose Gar
to the list of species that use canals as dispersal corridors or suitable habitat in
extreme southern Florida.
South Florida canals may break down dispersal barriers previously provided
by shallow-vegetated wetlands that experience seasonal dry-down. The pattern
of seasonal dry down of Everglades marshes is known to limit the abundance
of large-bodied fishes (Chick et al. 2004, Parkos et al. 2011, Rehage and Loftus
2007, Trexler et al. 2005). Biogeographic barriers (e.g., oceans, mountain ranges,
and catchment basins) typically limit faunal exchanges, but anthropogenic
alterations such as canals, can remove these natural barriers, resulting in biotic
homogenization (Rahel 2002). For instance, Mills et al. (1999) noted the expansion
of Morone americana Gmelin (White Perch), and Alosa psuedoharengus
Wilson (Alewife) beyond their historical distributions due to the construction
of the Erie Canal. Despite ongoing restoration efforts, only a small portion of
south Florida canals will be removed, making canals a permanent feature of the
Everglades ecosystem (CERP 1999). Thus, understanding the role of canals in
the ecosystem, including their role in native range expansions and as dispersal
corridors and habitat for native and non-native fishes, is a critical component of
understanding the ecology of south Florida.
We thank A. Brown at the USFWS Welaka National Fish Hatchery for the identification
of five specimens. We thank R.H. Robins, Florida Museum of Natural History, and J. Herrera,
Fish and Wildlife Research Institute, Fish and Wildlife Conservation Commission
for providing voucher collection records. We thank collaborators with the National Park
Service, particularly J. Kline. We thank R. Boucek, C. Henry, M. Anderson, and numerous
volunteers and interns for field assistance, as well as S. Lee and B. Feger for their valuable
comments on earlier versions of this paper. This project was funded by the National Park
Service’s Critical Ecosystems Studies Initiative (CESI; project # J5298-10-011), and developed
in collaboration with the Florida Coastal Everglades LTER program under NSF
DEB-0520409. This is contribution #555 of the Southeast Environmental Research Center,
Florida International University.
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