Conservation biology of the smalltooth
sawfish: science to help save the USA's first
endangered elasmobranch
Tonya Wiley and Beau Yeiser
Center for Shark Research
Elasmobranch Conservation Biology
Program
What are sawfish?
• Members of the family
•
•
•
•
Pristidae
A type of ray
All possess the distinctive
toothed rostrum or saw
Inhabit tropical and subtropical
coastal, estuarine and fresh
waters
Seven known species, six in
Pristis
• Taxonomy is still confused and
needs revision
• Historically largetooth and
smalltooth sawfish in the US
Pristis pectinata in US waters
• Historically common
•
from the Mexican
border to Carolinas
Summer migrations
from Florida and
Georgia north to
Carolinas and Virginia
(and sometimes even
Long Island)
The decline of P. pectinata
•
CPUE (lb/gear units)
the population is
estimated to have
declined in excess of
95%
Extirpated from most
of its historic range,
only occurs regularly
in southwest Florida
and Florida Keys
Louisiana sawfish abundance
12
9
6
3
0
19
45
19
47
19
49
19
51
19
53
19
55
19
57
19
59
19
61
19
63
19
65
19
67
19
69
19
71
19
73
19
75
19
77
• From 1900 to 2000
15
Year
The causes of the P. pectinata
decline
• Mortality in fisheries
•
•
(commercial and
recreational),
especially due to nets
Loss of important
nearshore habitat,
especially for the
juveniles
Late maturing,
produce few young
May 2007-East Cape Canal
Male Size at
Maturity
March 2002-Nine Mile Bank
Previous data
May 2007-East Cape Canal
270 cm (~9 feet)
July 2007-Florida Keys
March 2003-Nine Mile Bank
New data between
320-372 FL
340-395 STL
(~11 feet)
The USA’s first endangered
elasmobranch
• TOC petitioned for ESA listing
in 1999
• Status review
• April 1, 2003
P. pectinata was added to the
US Endangered Species List
• Also:
– Protected in Florida since
1992
– Critically Endangered listing
by IUCN
– Endangered Listing by AFS
– CITES Appendix 1
Mote research on P. pectinata
• Goal is to provide the
scientific basis for
population recovery
– Determination of
distribution and
abundance
– Identification of critical
habitat
– Population genetics
– Population and habitat
modeling
Outreach & Education
• Ask the public to report any
•
•
•
captures or sightings of
sawfish
Texas to North Carolina
Public can easily identify
sawfish correctly
Due to rarity, the public is a
good way to sample a wide
area continuously
Sawfish encounters 1998-2007
Sawfish encounters 1998-2007
Size and depth distributions
•
•
Frequency
40
30
20
10
70
0
60
0
50
0
40
0
30
0
20
0
10
0
0
0
•
reported
Majority of animals
reported are juveniles
Small P. pectinata limited
to shallow waters (<5m)
Larger P. pectinata have a
wider depth distribution
50
Estimated length (cm)
80
y = 0.0297x - 2.4076
R2 = 0.1345
70
60
Depth (m)
• Full size range of animals
60
50
40
30
20
10
0
0
100
200
300
400
Total length (cm)
500
600
Field Surveys
Rod and reel
Gillnet and seine
Longline
Spring Juvenile Surveys
Grocery Creek
Mud Bay
Last Huston Bay
Huston
Coves
•13 sawfish captured
Whitewater
Bay
Eagle Key
•11 YOY
•2 Immature
•2 new nursery locations
(Huston Coves & Bay)
East Cape Canal
Habitat use through manual
tracks
Habitat use by juvenile P.
pectinata
• Movements are
•
•
strongly influenced by
tide
Remain in very
shallow water (<50
cm)
Relatively small home
range over short
periods (days) and
often longer periods
(months)
High tide
Mid tide
Low tide
Habitat use by juvenile P.
pectinata
Site fidelity studies
•Use moored acoustic
listening stations to
record the
presence/absence
and movements of
sawfish
VR 2 monitoring
Station presense
1551
1550
1549
4/17/2003 0:00
4/18/2003 0:00
4/19/2003 0:00
4/20/2003 0:00
4/21/2003 0:00
4/22/2003 0:00
4/23/2003 0:00
1548
Time
4/24/2003 0:00
4/25/2003 0:00
4/26/2003 0:00
4/27/2003 0:00
4/28/2003 0:00
4/29/2003 0:00
Satellite telemetry of large P.
pectinata
• Wildlife
•
Computers PAT
tags used to
examine longerterm movements
of sawfish
Archive location,
depth and temp.
data and then
send via satellite
after pop-up
Satellite Tagging
Four sawfish:
400 cm TL F - Nov 2006
382 cm TL F - Nov 2006
210 cm TL F - May 2007
330 cm TL M - May 2007
Satellite Tagging-Results
Days Since Release
0
20
40
60
80
100
0
-10
Depth (m)
-20
-30
-40
-50
-60
-70
-80
06A0532 Released Nov 14 2006
06A0533 Released Nov 15 2006
•Two females
•Data from November 2006 to
February 2007
•Similar depth profile
•Data still being analyzed
120
Starting this Fall…
• Monitor the movements,
residency time, possible
aggregations and habitat
use of large sawfish in
Everglades National Park
and the Florida Keys
using BRUVS, and PAT
and SPOT tags
BRUV’s
Critical habitat for P. pectinata
• The next step is to
determine critical habitat
• Depth, salinity,
temperature, substrate
etc
– Juvenile areas
• Pupping
• Growth to maturity
– Adult areas
•
•
•
•
Feeding
Mating
Aggregations
Migrations
Critical habitat of P. pectinata
• Major factors appear
to be:
– Estuarine areas
(especially around
river months and
lower reaches of
rivers)
– Shallow banks along
mangrove shorelines
(juveniles)
– Deep channels
through shallow areas
(adults)
Genetics Collaborations
• Demian Chapman (Pew Institute for Ocean Science) and Kevin
Feldheim (The Field Museum)
• Objective 1: Determine whether multiple discrete breeding
populations of sawfish remain in the U.S. that should each be
managed independently and locally or whether there is only one
breeding population that should be managed as a unit, cooperatively by federal and state agencies. (philopatry, relatedness)
• Objective 2: Assess the population history of smalltooth sawfish in
their SW Florida “stronghold” and determine whether they have
suffered a loss of genetic diversity that may compromise their ability
to survive and reproduce in the future.
• Mahmood Shivjy-Nova Southeastern University
• Objective: DNA forensics to identify species of fins and rostra in
trade
Acknowledgements
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National Marine Fisheries Service
Disney Wildlife Conservation Fund
Florida Fish and Wildlife Conservation Commission
Munson Foundation
Florida Power & Light
National Fish and Wildlife Foundation
National Geographic Conservation Trust
John Ball Zoo Society
Mote Scientific Foundation