Casey Key Loggerheads 2011
Tony Tucker

Dataset credit

Data provider
Mote Marine Laboratory
Originating data center
Satellite Tracking and Analysis Tool (STAT)
Project partner

Project sponsor or sponsor description
Disney Worldwide Conservation Fund supported this project though a grant to the Longlines and Loggerheads project.

The project Assessment of loggerhead turtle habitats that overlap with reef-fish bottom longline fisheries on the West Florida Shelf, was funded in part by a grant awarded from the Sea Turtle Grants Program proposal 11-027R. The Sea Turtle Grants Program is funded from proceeds from the sale of the Florida Sea Turtle License Plate. Learn more at
Morrison Family Foundation
Wooster School Field Studies Program
Pineview School
Tom and Rosemary Costello


Primary contact Tony Tucker Mote Marine Laboratory
Data entry Michael Coyne



Reports from National Marine Fisheries Service (2009) recently identified a high level of estimated takes of sea turtles in the bottom longline portion of the Gulf of Mexico Reef Fishery, based on onboard observer data. Mounting pressure has come from environmental groups to act immediately to protect imperiled sea turtles in the Gulf of Mexico. The fisheries observer data revealed that the Gulf of Mexico bottom longline fishery, which targets reef fish like grouper and tilefish, resulted in the capture of nearly 1,000 threatened and endangered sea turtles between July 2006 and the end of 2007. Coalitions of environmental groups have asked that the commercial bottom longline fishery be suspended until the National Marine Fisheries Service meets its legal obligations under the Endangered Species Act to ensure that the fishery does not imperil sea turtles and other threatened species in the Gulf of Mexico.
Of particular concern for the groups are loggerhead sea turtles, which accounted for 799 of the 974 captured turtles in the government analysis. This is more than three times the number of loggerheads the Service authorized the fishery to take in 2005 and may well jeopardize the species. Loggerhead nesting populations in Florida have dropped by over 40 percent over the past 10 years. The large number of juvenile and reproductive adult turtles injured or killed by the bottom longline fishery is likely contributing to this steep decline.
The Gulf of Mexico bottom longline fishery operates primarily off the west coast of Florida, an area that also provides key habitat for several sea turtle species, including loggerhead, Kemp's ridley, and green turtles. Bottom longline gear generally consists of a four- to 10-mile-long mainline made of steel cable or monofilament with up to 2,100 hooks. Sea turtles are caught on the lines when they attempt to eat the bait from hooks or become entangled when swimming near a line. Unable to surface for breath, they suffer injury or death.
Even though the bottom longline fishery has far exceeded the number of turtles it is allowed to take under the Endangered Species Act, the National Marine Fisheries Service has not closed the fishery while it studies options for reducing turtle take. The fishery is also known to catch endangered smalltooth sawfish and could affect staghorn and elkhorn coral, which are also protected under the Endangered Species Act.
Clearly there is a pressing and urgent need for studies that employ cutting edge technologies to evaluate the temporal and spatial components of overlap between fishery effort and sea turtle home ranges and foraging areas.
This is a high priority for Sarasota nesting beaches are home to 40 percent of loggerhead (Caretta caretta) nests in the Gulf of Mexico. This species is protected under the U.S. Endangered Species Act of 1973, the Marine Turtle Protection Act Chapter 370.12 (Florida Administration Code), and local regulations. Internationally, it is considered “vulnerable” and is listed as a species threatened with extinction in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora.
Conservation efforts are hampered by lack of knowledge of the distant foraging grounds where turtles spend 99 percent of their lives. This project will use satellite technology to identify the foraging areas of adult female loggerheads as they leave the breeding beaches and enter the zones of longline bycatch in the Gulf of Mexico.

Amendment 31 background: NOAA Fisheries Service implemented a rule, effective October 16, 2009, to reduce the sea turtle bycatch in the bottom longline component of the Gulf of Mexico reef fish fishery. The rule prohibits bottom longlining for Gulf reef fish east of 85o30’W longitude (near Cape San Blas, Florida) shoreward of the line approximating the 35-fathom depth contour (see map and table) with a restriction of 1,000 hooks per vessel with no more than 750 hooks being fished or rigged for fishing at any given time. For the purpose of this paragraph, “hooks rigged for fishing” means hooks attached to a line or other device capable of attaching to the mainline of the longline. During vessel transit through closed zones, no reef fish may be possessed unless bottom longline gear is appropriately stowed, meaning that a longline may be left on the drum if all gangions and hooks are disconnected and stowed below deck; hooks cannot be baited, and all buoys must be disconnected from the gear, but may remain on deck. As a reminder, in the case of the 35-fathom regulation line intersecting a marine reserve, fishermen must also adhere to the regulations for the reserve. The purpose of this rule is to balance the continued operation of the bottom longline component of the reef fish fishery while maintaining adequately protective measures for loggerhead sea turtles pending implementation of long-term mitigation measures.
However, there are fundamental facets of loggerhead spatial ecology that were not addressed (including spatial, temporal, and depth overlap) in Amendment 31 that suggest the NMFS mitigation measures (collectively identified as Amendment 31) are not completely addressing early biological recommendations suggested by previous MML or FWC tracking studies (see Fig. 3, 4, 5). Specifically, the biological data already gleaned, when augmented by the proposed research project should robustly demonstrate that the measures of Amendment 31 continue to leave reproductive females at risk (Tucker 2008). The goal of this proposal is to answer some of the key management questions remaining about the extent of overlap between endangered sea turtle on the west Florida shelf and the Gulf of Mexico grouper longline fishery.
Potential for sea turtle take by Gulf of Mexico grouper longliners needs review. The current take by grouper longlines appears to be low or negligible, but data are really deficient to draw firm conclusions for the purposes of management. Anecdotes suggest that on occasions, potential high levels of take can occur and in such cases, the specifics need to be better identified.

Projected outcomes: rigorous estimates of spatial and temporal habitat use by sea turtles that will produce management information that is critical to the conservation of sea turtles and which can be incorporated to refine Amendment 31.



Supplemental information

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Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downlodable online. Other attributes may be obtained upon provider's permission unless otherwise noted below.

This section explains attributes included in the original dataset. OBIS-SEAMAP restricts the attributes available to the public to date/time, lat/lon and species names/counts only. Should you need other attributes described here, you are encouraged to contact the data provider.

Attributes in dataset provided

Attribute (table column)Description
project_idSTAT Project ID
prognumProgram number
tag_idPTT ID
datetime_utcDate and time in UTC
lcLocation class
iqQuality indicator
latitudeLatitude 1
longitudeLongitude 1
dir1Dir 1
nb_mesNumber of messages received
big_nb_mesdefinition not provided
best_levelBest signal strength in dB
pass_durationPass duration in seconds
nopcNumber Of Plausibility Checks successful (from 0-4)
calcul_freqCalculated frequency
altitudeAltitude used for location calculation
speciesSpecies name
sp_tsnITIS Taxonomic Serial Number
lc_filterParameters to location filtering
speed_filterParameters to speed filtering
distance_filterParameters to distance filtering
topo_filterParameters to topo filtering
time_filterParameters to time filtering
angle_filterParameters to angle filtering
life_stageLife stage of the animal
genderGender of the animal
wetdryWet or dry
wetdry_filterParameters to Wet or dry filterint
obs_datetimeDate and time (local time zone)
timezone_hTime difference from UTC
obs_countAnimal count (always 1)
Marine mammals0
Sea turtles24,544
Rays and sharks0
Other species0
Non spatial0
Non species0
Date, Begin2011-05-17
Date, End2012-05-03
Temporal prec.111111
Latitude19.52 - 30.29
Longitude-91.75 - -76.70
Coord. prec.3 decimal digits
Data typeTelemetry location
TracklinesYES (ID: 762)
Contr. throughSatellite Tracking and Analysis Tool
StatusNot published
Sharing policy Permission required
Also availalbe from None
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See metadata in FGDC XML
See download history / statistics