General Information

capture, sighting
Surface-pelagic Drift Community (Northern Gulf)
2
Northwest
28.91 -87.25
Ceriani, Simona A; Hardy, Robert F; Hirama, Tomo; Witherington, Blair E
Hardy, Robert F - Phone Number: (727) 896-8626, Email: robert.hardy@myfwc.com
Florida Fish & Wildlife Conservation Commission - Fish & Wildlife Research Institute, Disney's Animals, Science and Environment
state agency, commercial
Active
8/2005
n/a

Equipment and Methods

boat survey, dip net

Sampling and Effort

Visual Capture
Sampling regime: opportunistically opportunistically
Measure of effort: obs/distance cap/distance
pelagic
pelagic marine
13 1814
405

Captures and Sightings Information

Species No. of
Captures		 No. of
Sightings		 Min Size*
(cm)		 Max Size*
(cm)		 Mean Size*
(cm)		 FP
Observed		 Life Stages** Comments
Green Turtle (Cm) 73 57 16.1 32.0 24.0 No O, N
Loggerhead (Cc) 9 7 5.5 21.7 12.3 No O, N, S, A
Kemp's Ridley (Lk) 25 8 19.8 25.4 22.5 No O, N
Hawksbill (Ei) 5 0 16.2 23.7 19.4 No O
Leatherback (Dc) 0 1 n/a n/a n/a n/a A
*All size measurements are SSCL unless otherwise indicated
** For Cm, Cc, Lk, & Ei: O - Oceanic-stage juvenile; N - Neritic-stage juvenile; S - Subadult; A - Adult. For Dc: I - Immature; A - Adult. n/a = not applicable; n/r = not reported.

This report adheres to the following size ranges for life stage classification for these species:

Green turtle Loggerhead Kemp's ridley Hawksbill
Oceanic-stage juvenile < 25 cm SCL < 30 cm SCL < 25 cm SCL < 25 cm SCL
Neritic-stage juvenile 25-69 cm SCL 30-69 cm SCL 25-39 cm SCL 25-64 cm SCL
Subadult 70-84 cm SCL 70-79 cm SCL 40-59 cm SCL 65-74 cm SCL
Adult ≥ 85 cm SCL ≥ 80 cm SCL ≥ 60 cm SCL ≥ 75 cm SCL
Leatherback
Immature < 135 cm OCL
Adult ≥ 135 cm OCL

Other Information Collected

diet
stable isotopes
satellite tracking
diving behavior

Project Summary

This broad study area includes pelagic waters south of Louisiana, Mississippi, Alabama, and northwestern Florida. These waters are accessed by ports at Venice, Louisiana, Pensacola, Florida and Apalachicola, Florida. It is part of a larger study of sea turtles in surface-pelagic drift communities in the Gulf of Mexico and Atlantic Ocean. Surface-pelagic post-hatchling and juvenile turtles inhabit surface drift-lines located in the northern Gulf of Mexico. They are observed and captured during linear transects through oceanic fronts, slicks, windrows, Sargassum patches, and other drift material. Transects take place seasonally, principally July to October, during periods of calm sea state (Beaufort force 0-3). Capture rates (turtles per time, distance, or area) of post-hatchling turtles are highest for transects in Atlantic shelf waters near the Gulf Stream. Capture rates of small juveniles are highest for transects in the Gulf of Mexico 40-70 NM from Florida. All Kemp’s ridleys captured so far have been from the Gulf of Mexico. Behavioral measurements and diet analysis suggest that loggerhead post-hatchlings are float-and-wait foragers of mainly animal material, with a diet that includes mostly neuston from the Sargassum community, pleuston, jellies, and drift carrion.

Documents

No documents uploaded.

Literature/Reports Produced

Witherington, B. 1994. Some "lost-year" turtles found. In: Schroeder, B.A., and B.E. Witherington (comps.). Proc. 13th ISTS. NOAA Tech. Memo. NMFS-SEFSC-341, pp. 194-196.

Witherington, B. 1994. Flotsam, jetsam, post-hatchling loggerheads, and the advecting surface smorgasbord. In: Bjorndal, K.A., A.B. Bolten, D.A. Johnston, and P.J. Eliazar (comps.). Proc. 14th ISTS. NOAA Tech. Memo. NMFS-SEFSC-351, pp. 166-168.

Witherington, B. 2000. Habits and bad habits of young loggerhead turtles in the open ocean. In: Abreu-Grobois, F.A., R. Briseno Duenas, R. Marquez, and L. Sarti (comps.). Proc. 18th ISTS. NOAA Tech. Memo. NMFS-SEFSC-436, pp. 34-35.

Witherington, B.E. 2002. Ecology of neonate loggerhead turtles inhabiting lines of downwelling near a Gulf Stream front. Marine Biology 140:843-853.

Witherington, B., and S. Hirama. 2006. Little loggerheads packed with pelagic plastic. In: Pilcher, N.J. (comp.). Proc. 23rd ISTS. NOAA Tech. Memo. NMFS-SEFSC-536, pp. 137-138.

Witherington, B., and S. Hirama. 2006. Sea turtles of the epi-pelagic Sargassum drift community. In: Frick, M., A. Panagopoulou, A. Rees, and K. Williams (comps.). Book of abstracts. 26th ISTS. International Sea Turtle Society, Athens, Greece, pp. 209.

Witherington, B. 2006. Threats to Neonate Sea Turtles in Atlantic Surface Waters off Florida. Final report submitted to the National Fish and Wildlife Foundation. May 25, 2006. 32 pp.

Witherington, B. E., S. Hirama, and R. F. Hardy. 2012. Young sea turtles of the pelagic Sargassum-dominated drift community: habitat use, population density, and threats. Marine Ecology Progress Series 463:1–22. http://www.int-res.com/abstracts/meps/v463/p1-22/