The Longnose Gar Lepisosteus
osseus (Linnaeus, 1758) never fails to fascinate the nature observer. The Gars have many unique traits making them
unlike most other fishes. They are
easily distinguishable by the extremely long snout, numerous sharp teeth, long
cylindrical body form, bony scales and the abbreviated heterocercal tail. Along with the Sturgeons, Paddlefish,
and Bowfin, they are living representatives of some of fishes that existed over
100 million years ago. Say what? Yes they possess traits that were present on ancenstral Gars over 100 million years ago!
Longnose Gar captured in Virginia (photo by J.D. Schmitt) |
In Virginia, the Longnose Gar is the only native Gar and is the
most widespread species in North America. The name Lepisosteus comes from a combination of
the two words “lepis” the Greek word for "scale",
and “osteos”
which is Latin for "bony".
Similarly Lepidoptera is an order of insects, butterflies and moths,
named for scale and greek “pterin” for wing. In the case of the Gars, the name is used to
describe the extremely hard ganoid scales.
The specific epithet osseus is
also Latin for the word "bony".
That’s redundant, but you can’t blame it on Linnaeus; Carolus Linneaus
originally classified this fish as Esox
osseus, or Gar Pike.
No other fish in Virginia has such a hard bony covering. The ganoid scale emerged at a time when very
large toothy aquatic reptiles, the large pliosaurs and relatives were still
around. This bony covering is extremely
difficult to pierce even with a sharp filet knife. Each ganoid scale is rhomboid in shape and
has an articulating dorsal peg that articulates with a ventral socket joint on
the adjacent, dorsally-placed scale. Ganoid
scales have a bony basal layer, a layer of dentine, and an outer layer of
ganoine (an inorganic bone salt). Ganoid
scales in gar are tightly overlapping on all parts of the body creating the
diamond-shaped pattern and the rather inflexible body form.
Top: Lateral scales of Longnose Gar (photo by Uland Thomas. Bottom: Close up of Longnose Gar scales (photo by D.J. Orth) |
The gar body form is a long flexible cylinder, not designed for sustained
swimming. The dorsal and anal fins are both set well back on the body, and with
a large rounded tail fin that provides stability during caudal thrust. The
gar is an ambush predator that sits and waits motionless until potential prey
are near. With a rapid tail thrust andhead sweep they impale the prey fish in their long toothy mouth. The
Longnose Gar relies more on the speed of lateral movement rather than biting to impale a prey fish; there is very little biting force at the tip of its jaw. Recently a diet study on Longnose Gar in
Charleston harbor and associated estuaries of South Carolina confirmed that the
adults are opportunistic piscivores. In
this location the dominant in the diet were Atlantic Menhaden, shad, drum,
killifishes, mullet, and Penaeid shrimp.
In Virginia tidal populations, the top five prey consumed by adult
Longnose Gar were White Perch, Menhaden, Fundulus spp., Atlantic Croaker and Spot.
Longnose Gar is easily distinguishable from other gars by its long,
narrow snout. The snout length is more
than 13 times its narrowest width in specimens 50 mm long or larger. Juveniles have a shorter snout, which grows proportionally faster than the body. Other species gar can be distinguished by
snout shape and pigment patterns. The spots
on the body of the Longnose Gar are smaller and generally less well developed
than on Spotted Gar.
Top; Four Gars compared (Source Kentucky Dept of Fish & Wildlife Resources). Bottom: Skulls of Longnose Gar in lateral view and dorsal view (photo: D.J. Orth) |
Gars have a bimodal system for respiration. They can obtain oxygen via gills or via air
breathing. The lung is highly vascularized and homologous to
the tetrapod lung. It occupies 10% of the volume of the fish. It is this use of bimodal respiration that allows the
Longnose Gar to be successful in many waters with low oxygen content that would otherwise be inhospitable. Yet in hypoxic (low oxygen) conditions they may continue with
normal levels of activity as they rely on air breathing. Consequently they are widely dispersed in the
lowland lakes, rivers, and streams of the Atlantic and Gulf slopes and
throughout the Mississippi River and lower Great Lakes basins.
Longnose Gar are primarily freshwater fish; however, they have
been captured in tidal rivers at a maximum salinity up to 15-21 ppt. In some studies, they appear to
move significant distances. There also tends
to be a springtime movement to smaller tributaries for spawning.
Do not eat Gar eggs! Unlike the Paddlefish, Sturgeon and Bowfin,
the eggs of Gars are not used for caviar.
In fact they are highly toxic to mammals and birds, but not fishes. This
remains an unsolved mystery. One presumes that fishes would be a primary
source of predation on Gar eggs, yet this egg toxin does not deter fishes from eating the eggs. Why evolve an egg toxin specific to mammals and birds?
Many
authors suggest that there is no sexual dimorphism in Longnose Gar other than
females being larger than males .
However, Long and Ballard in collections of breeding Longnose Gar,
reported that adult females possessed a silvery body coloration, while males
had a golden cast to their scales.
Patrick McGrath analyzed morphometrics of male and female Longnose Gar
and demonstrated that males had a longer anal-fin base and wider heads and
mid-snouts than females.
Longnose
Gar may spawn in relatively barren shorelines or quiet vegetated habitats. Longnose The female spawns with one to
several males who use their snout to nudge and position the female, followed by
a simultaneous release of eggs and sperm.
Gar lay sticky eggs on bottom, often in weedy
bays on submerged vegetation. The dark
eggs are about 3mm in diameter and poisonous for humans to eat. The
may hatch in 6 days at temperatures between 18-20C. By day four the embryo still has a large yolk
sac and has developed an adhesive organ on the head. The adhesive organ is larger than the embryonic
eye. By the time of hatching and yolk
sac absorption, the eye size is larger than the adhesive organ. The adhesive organ on its head helps the
embryo to attach to vegetation and other structures where they hang
vertically. They lose the adhesive organ
when snout and mouth is fully formed and feeding can commence.
Top: Drawings to two stages of larval Longnose Gar with (left) and without (right) adhesive organ. Bottom: Photograph of larval Gar with adhesive organ. (Source). |
The
smallest juveniles have an appearance very different from adults. The small juveniles have a long lateral
stripe, shorter snout, and long caudal ray filament. At this stage, the Longnose Gar are surface feeding
on copepods, cladocerans, and aquatic insects before making the transition to
piscivory.
Longnose Gar are not classified as a game fish;
however, in recent decades they have begun to gain a specialized
following. The Texas State Record
Longnose Gar was a 50 pound 5 ounce specimen taken from the Trinity River in
1954. The Longnose Gar is a special challenge for
the interested angler. However, this specialized
fish is best pursued with a specialized fishing technique. You
simply do not want to embed a treble hook into the bony jaw of the Gar. Neither you nor the Gar will be happy about
the outcome. One of the alternative techniques
is the use of a rope lure. With this method the unbraided rope gets
tangled in the teeth as the Gar attacks the bait.
Rope lures used specifically to target Gars (source) |
Also, bowfishers have always known that the Gars are a suitable target as they lie motionless near the water surface -- easy targets for an accurate bowfisher. While bowfishers have quietly targeted Gars for sport and an occasional meal, recently bowfishing tournaments have become popular. And the tournaments have raised an ethical dilemma regarding the harvest and subsequent waste of native Gars. We will see if tournament organizers treat Longnose Gar and other Gars differently in future tournaments.
Jason Emmel with a Longnose Gar bowfished in Virginia. (Photo: J.D. Schmitt) |
Fossil
Gars have been found in North America, South America, Africa, India, and
Europe, though the origins of this group remain highly uncertain. Perhaps the ancestral Lepisosteiform fish
arose before or during the Cretaceous, which began 145 million years ago. This ancestral fish arose in the late
Jurassic before the breakup of the supercontinent Pangea.
Closest relatives to the Gars are
Bowfin (Amia calva). The most recent phylogenetic analyses
support the hypothesis that these two groups have a common ancestor and form a
basal-sister group (Holostei) to all other bony fishes (Teleostei).
Longnose Gar have largely been ignored in the development of
fisheries management programs. Although
other Gars (Alligator Gars and Tropical Gars) are declining in many areas,
there is little directed effort to monitor status of Longnose Gar populations
throughout its range. No estimates exist for
sport or commercial harvest and the effect on populations.
Scales may have been used as arrow points by Native Americans. Some artisans are using Gar scales to make earrings.
Scales may have been used as arrow points by Native Americans. Some artisans are using Gar scales to make earrings.
If you are interested in more information about the family
Lepisosteidae, the Gars, then check out this website now!
I believe I found one of these washed up on the beach in St. Augustine, Florida yesterday. I have a photo of it. You can email me at aeronmack at yahoo dot com and I can forward it to you. Found yesterday morning, January 29th, 2021, washed up on the beach after high tide.
ReplyDelete