Transcript Captive biology of the pelagic stingray, Pteroplatytrygon

Pteroplatytrygon (Dasyatis)violacea
A Review
Henry F. Mollet, Juan M. Ezcurra, John B. O'Sullivan
Monterey Bay Aquarium, 886 Cannery Row,
Monterey, CA 93940, USA
Acknowledgements
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Monterey Bay Aquarium Brorsen Steve, Greenwald Scott, Farwell Charles, Franklin
Veronica, Ingram Kris, Kochevar R, Scott R, Wrobles Dave, Welsh Joe
California Catania Dave (CAS), Ebert Dave (US Abalone), Holts Dave
(NOAA/NMFS), Morales Pat (CAS), O'Brian John (DFG), Shaw Mike (Sea World),
Smirl Kent (DFG), Walker H.J. (SIO), Zorzi George (CAS)
USA Bourdon Jim, Conlin Mark, Crow Jerry (Waikiki Aq,), Henningsen Alan
(Baltimore Aq.), Neer Julie (LSU), Pooley S (NOAA/NMFS), Rosenberger L (UC)
Brazil & Mexico Rincon Getulio (Rio Grande U.), Villavicencio Carlos (UABCS )
Europe Bentivegna Flegra (Zoological Station Naples), Bortolotto Alessandro,
(Fondazione Cetacea Milan),Garibaldi Fulvio (LBMLR Genova), Haynes Rod
(Benalmadena SLC), Henderson Aaron (NUI Galway)
Japan Nishida Kiyonori (Osaka Aquarium), Chai Kiyoshi (KAMPA )
South Africa Compagno Leonard (SAM), Dudley Sheldon (NSB)
Australia & New Zealand Francis Malcolm (NIWA), Last Peter (CSRIO), Ministry of
Fisheries, Stevens John (CSIRO), Stewart Andrew (MNZ)
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Introduction
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La Paz 2000
Penn State 1999 (Jim Bourdon)
Guelph 1998
Seattle 1997
(plus poster with Scott Greenwald and Jim Bourdon)
• New Orleans 1996
• Edmonton 1995
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Timeline 1800-2000
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Worldwide Distribution
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Disc width Distribution
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Taxonomy
• Bonaparte (1832-1941). Trygon violaceum, Trygon Cuv.
junior synonym to Dasyatis Raf.
• Fowler (1910). Pteroplatytrygon subgenus of Dasyatis.
• Compagno (1987). Pteroplatytrygon available as a
monotypic genus. Elevated to genus, based on
morphometrics, disc color, streamlined eyes.
• P. Deynat, J. Bourdon (pers. comms.).
Dermal denticles and dentition within Myliobatiformes
indicated that Dasyatis violacea is clearly set apart from
the other Dasyatis.
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Mass -DW Relationship
(back transformed Y-on-X power regressions)
• M = 49.5 DW3.607 (n = 15, Edmonton 1995)
• DW in meters, 50 kg was predicted mass for
1 m DW pelagic stingray
• April 2000, largest female 0.96 m DW,
49.0 kg
• M = 44.9 DW3.321 (n = 181, Monterey 2000)
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Tooth Replacement Rates
with Jim Bourdon and Scott Greenwald
• Shed rate
3.4 ray-1 day-1
• Replacement rate
• 20.7 days row -1
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File splitting
with Jim Bourdon
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Dermal Denticles Shed Rate
with Jim Bourdon and Scott Greenwald
• First shed rate for any
batoid
0.68 ray-1 day-1
• Guesstimate for
replacement rate
44-88 days
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Population Genetics Project
with Joe Quattro
• Now in progress
• Atlantic: Brazil (Getulio Rincon); Ireland (Aaron
Henderson)
• Med Sea: Western Med (Rod Hayes); Ligurian Sea (Fulvio
Garibaldi)
• Pacific: California (John O'Sullivan, Julie Neer); Hawaii
(Jerry Crow, Ed Heist); New Zealand (Malcolm Francis)
• Additional samples needed & welcome
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One Big Problem with VBGF
• VBGF reasonable with
good statistics
• Applies to captive rays
2 years old and older
• 1st year growth rates
much too large!
• Affects age estimate of
our rays at capture!
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Comparison of Gompertz & VBGF
(3 parameter fits using estimated age)
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Disc width (cm)
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Gompertz
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DWoo DWo
Fem 100 15
Male 71 19
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VBGF
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k
DWoo DWo
0.44
0.55
Fem 104 -7.7
Male 68 -38
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k
0.32
0.71
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Estimated age (years)
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10
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Estimated age (years)
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Comparison of Gompertz & VBGF
(3 parameter fits incl. captive pup data)
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Density Related Fecundity?
• Review of reproductive data
• Feeding data at the
Monterey Bay Aquarium
• Could feeding cycles indicate possibility of
2 litters per year if food is available?
(i.e. lower density)
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Gestation and Parturition
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0.6
25
0.5
20
0.4
DWo
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0.3
Mean DW for 10
Japanese AQ litters
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5
0
0.2
Mo
Med. Sea Embryos
J J A
S O N D J F M A M
0.1
J J A S O N
D J F M A M
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0.0
Mass (kg)
Disc width (cm)
Review of Med. Sea and Japanese Aq. data
Gestation and Parturition
Review of NW Atlantic and NE Pacific data
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10
NW Atlantic
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15
10
5
5
suggested off C. Am.
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J J A
S O N D J F M A M J J A
S O N D J F M A M
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0
Disc width (cm)
W Med Sea
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MBA
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NE Pacific?
SeaWorld
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Steinhart
Disc width (cm)
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MBA
Off El Salvador
NW Atlantic ?
Weekly Feeding Amounts Phase 2
(Food Intake is Seasonal)
4 females & 2 males of phase 2
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Feeding is Seasonal for Both Sexes
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Amount fed
3.0
2.5
Males
2.0
1.5
Females
1.0
0.5
0.0
3.0
P2??
Amount fed
2.5
P1?
2.0
1.5
1.0
0.5
X Combined
0.0
1998
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Summary
• I covered distribution, taxonomy, morphometrics,
dentition, dermal denticles. No problems.
• Growth: Gompertz better than VBGF because 1st year
growth rates are likely smaller than what VBGF suggests.
• Seasonal food intake variation with 2 cycles/year.
Probably related to reproduction. Might suggest density
dependent fecundity. Need more data for Pacific.
• Model for pelagic sharks which are difficult to study and
impossible to keep in captivity?
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