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The
caudal fin lacks a well-defined lower lobe. Body color is
generally blue-gray to brown, with the ventral surface white.
Both jaws have 10 - 12 rows of teeth, with
88-128
teeth in the upper jaw and 84 - 176 in the lower jaw. The teeth
are rounded anteriorly and have a blunt cutting posterior edge.
The skin has numerous dermal denticles that vary in size and shape
(Bigelow
and Schroeder 1948; NMFS 2000).
Potentially
Misidentified Species:
The largetooth sawfish, Pristis perotteti, is similar in
body shape and size. It can be distinguished from P. pectinata
based on its having a somewhat longer rostrum, and by the number
of teeth on the rostrum: smalltooth sawfishes have 23 - 34 teeth
on either side of the saw, while largetooth sawfishes have 17 -
22 teeth. Further, P. perotteti has a distinct lower
lobe on the caudal fin. Largetooth sawfishes are quite rare
in Florida waters but have not yet been listed as Endangered species
because so little is known about their biology.
II. HABITAT AND DISTRIBUTION
Regional Occurrence:
Smalltooth sawfishes are a circumtropical species, and have been
documented from Europe, West Africa, the Red Sea and the Indian
Ocean. They have also been reported from the Philippines and
Australia, though these specimens may possibly have been misidentified
(Adams
1995; Simpfendorfer 2005). In
the Western Atlantic, the range extends from approximately southern
Chesapeake Bay south to Brazil, including Bermuda, the Caribbean,
and the Gulf of Mexico. However, observations of this endangered
fish are now regularly reported only from the waters of south and
southwest Florida, with occasional sitings as far north as the Indian
River Lagoon on Florida's East coast, and Tampa Bay on Florida's
West coast.
Records from the late 1700s and
early 1800s report smalltooth sawfishes being captured in waters
off New York and New Jersey during the summer months when water
temperatures were at their highest in these areas. However,
it is estimated that the historical
range ofPristis pectinata has contracted by more than 90%,
and the species is currently in danger of extinction.
IRL Distribution:
Records from the late 1800s show that the
IRL was an area of abundance for Pristis pectinata (Bean
1884; Evermann and Bean 1896). Today, they are only
rarely encountered.
III. LIFE HISTORY AND
POPULATION BIOLOGY
Age, Size, Lifespan:
Pristis
pectinata grows to a maximum length of 7.6 m (25 feet), though
it is more commonly observed at approximately 6 m (19.6 feet) (Simpfendorfer
2005). They
may live longer than 30 years based on specimens held in public
aquaria that lived in excess of 20 years (NMFS 2000).
Abundance:
Pristis pectinata has historically been described as "common"
or "abundant" in scientific research from the late 1800s
through approximately 1950 (Jordan and Evermann 1896; Breder
1952). The range of this species has contracted more than
90% (NMFS 2000) as the population rapidly declined. It has
been considered rare in Gulf of Mexico since the 1970s. Peninsular
Florida may be the only geographic are to host smalltooth sawfish
year round (NMFS 2000).
Reproduction:
Smalltooth
sawfishes are ovoviviparous and reproduce
via internal fertilization as occurs in all elasmobranchs.
Maturity is believed to occur
at approximately 10 years of age. Males measure at approximately
2.7 m (8.9 feet) in length, while females measure approximately
3.6 m (11.8 feet) at maturity (Simpfendorfer
2005).
There have
been no comprehensive studies on age and growth parameters in smalltooth
sawfishes, however, based on the biology of the closely related
largetooth sawfish (Pristis
perotteti), it is believed that
P. pectinata is slow to grow and mature. This would
suggest a low intrinsic rate
of increase as well as low rebound potential (Smith et al 1998).
Simpfendorfer (2000) modeled demography of the smalltooth
sawfish and reported an intrinsic rate of increase ranging from
0.08 - 0.13 years, with a population doubling time of 5.4 - 8.5
years.
Embryology:
Females
may carry 15 - 20 embryos (Bigelow and Schroeder 1953). Yolk
sac embryos resemble adults relative to position of the fins and
lack of a defined lower caudal lobe. During development, the
rostrum is soft and flexible, with rostral teeth remaining
entirely enclosed in a sheath of tissue until shortly after birth
(NMFS 2000). In Florida, young are born late winter and spring
and measure approximately 60 - 80 cm at birth (Simpfendorfer
2005).
The sheath of tissue covering the rostrum disappears shortly after
birth so young can feed and defend themselves.
No records exist for gestation period
for smalltooth sawfishes, however, in largetooth sawfish, gestation
lasts approximately 5 months, with females producing litters approximately
every other year (MNFS 2000).
IV. PHYSICAL TOLERANCES
Temperature:
Based on historical records of seasonal migration patterns, the
lower thermal limit for Pristis pectinata is approximately
16-18 °C (60.8 - 64.4 °F) (NMFS 2000).
Salinity:
Euryhaline. Pristis pectinata
is generally found in estuaries and shallow bays, but is known
to enter and remain in fresh water areas for extended periods of
time (NMFS 2000).
V. COMMUNITY ECOLOGY
Trophic Mode:
Smalltooth
sawfishes feed on small schooling fishes such as mullet and herrings,
typically using the rostrum to slash through schools, eating those
fish wounded in the attack. Some have been observed feeding
on crustaceans and other benthic organisms. In these cases,
the rostrum is often used to stir up the benthos, startling prey
(Bigelow and Schroeder 1953).
Predators:
Young Pristis pectinata may be vulnerable to attack by
sharks, but there are no other known predators.
Habitats:
Smalltooth sawfishes generally
inhabit inhabit shallow coastal waters of inshore bars and banks,
mangrove creeks, seagrass beds, and river mouths, primarily over
muddy or sandy bottoms. They occasionally enter freshwater.
They are most commonly observed within 1 mile of land, at depths
less than 10 m (32.8 feet) (NMFS 2000).
Young Pristis pectinata are most
often found on sallow sands and mud banks no deeper than 30 cm (11.8
inches). Larger juveniles are dependent on shallow inshore
habitats near river mouths and estuaries where water depth averages
approximately 2 m (6.6 feet). Adults can be found in waters
of 100 m depths (Simpfendorfer
2005).
VI. SPECIAL STATUS
Special Status:
Pristis pectinata, has been listed
Federally as an Endangered species since April 1, 2003, and was
the first elasmobranch to be listed under the Endangered Species
Act of 1973. It has been listed by the State of Florida as
Endangered since April, 1992. The National Marine Fisheries
Service (NOAA Fisheries) is the lead agency responsible for imperiled
marine organisms.
In
the early 1900s large numbers of sawfishes were captured and killed
by recreational fishers, who removed the rostra of sawfishes as
trophies. Pristis pectinata has never been
commercially important, but large numbers of them were incidentally
captured in commercial fisheries operations due to the ease with
which their rostra became entangled in lines and nets. This
is likely the primary cause of the rapid decline observed in the
overall population, though habitat loss and degradation as well
as pollution effects also played significant roles (NMFS 2000).
Current
threats to smalltooth sawfishes include: habitat degradation
and loss of wetland habitat, eutrophication of coastal waters, point
and non-point sources of pollution, increased sedimentation and
turbidity, and hydrologic modification for human uses (NMFS 2000).
Current conservation efforts
are confined to monitoring activities, life history research, raising
public awareness, and possession prohibition. A management
and recovery plan is under development (Simpfendorfer
2005).
VII.
REFERENCES
Adams, W.F. and C. Wilson. 1995.
The status of the smalltooth sawfish, Pristis
pectinata Latham 1794 (Pristiformes:
Pristidae), in the United States. Chondros
6(4):1-5.
Bean, T.H. 1892. Observations upon fishes
and fish culture. Bull. U.S. Fish.
Comm. 10:49 - 61.
Bigelow, H.B. and W.C. Schroeder. 1953.
Sawfishes, guitarfishes, skates and
rays. Pp. 1 - 514 in: Tee-Van, J.,
C.M. Breder, A.E. Parr, W.C. Schroeder,
and L.P. Schultz (eds.). Fishes of
the Western North Atlantic, Part Two.
Mem. Sear Found. Mar. Res. I.
Bigelow, H.B. and W.C. Schroeder. 1948.
New genera and species of batoid
fishes. J. Mar. Res. 543 - 566.
Breder, C.M. 1952. On the utility of
the saw of the sawfish. Copeia
1952 (2):90 - 91.
Evermann, B.W. and B.A. Bean. 1892.
The fishes of Texas and the Rio Grande
Basin considered chiefly with reference
to their geographical distribution.
Bull. U.S. Fish. Comm. 12:57-126.
Gilmore, R.G. 1995. Environmental
and biogeographic factors
influencing ichtyofaunal diversity:
Indian River Lagoon. Bull. Mar. Sci.
57(1):153-170.
Last, P.R. and J.D. Stevens. 1994.
Sharks and Rays of Australia. CSIRO,
Australia. 513 pp.
National Marine Fisheries Service. 2000.
Status review of the smalltooth sawfish
(Pristis pectinata).
Schmid, T.H., L.M. Ehrhardt, and F.F. Snelson.
1988. Notes on the occurrence
of rays (Elasmobranchii, batoidea) in the
Indian River Lagoon system, Florida.
Fl. Sci. 51(2):121-128.
Simpfendorfer, C.A. 2005. Threatened
fishes of the World: Pristis pectinata
Latham, 1794 (Pristidae). Environmental
Biology of Fishes
(2005)73:20.
Simpfendorfer, C.A. 2000. Predicting
population recovery rates for endangered
Western Atlantic sawfishes using demographic
analysis. Environmental
Biology of Fishes. 58:371-377.
Snelson, F.F. and S.E. Williams. 1981.
Notes on the occurrence, distribution,
and biology of elasmobranch fishes in the
Indian River Lagoon system,
Florida. Estuaries 4(2):110 - 120.
Stehmann, M. 1981. Pristidae.
In: W. Fischer, G. Bianchi, and W.B. Scott (eds.)
FAO species identification sheets for fishery
purposes. Eastern Central Atlantic
Fishing Areas 34, 47 (in part). Vol.
5.
Report by:
K. Hill, Smithsonian Marine Station
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