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Sea Turtle and Marine Mammal Risk Assessment Map for Explosive Platform Removal

Providing a resource that may be used to assess the likelihood of encountering marine protected species in the Gulf of Mexico.

This guide may provide useful information to companies planning explosive platform removals. Turtle-hours and dolphin-hours may serve as an index of sea turtle or marine mammal activity and may be used to assess the likelihood of encountering marine protected species in the area.

Lease blocks with higher turtle-hour or dolphin-hour values may be at higher risk of encountering marine protected species during future removal operations. Note that some lease blocks received more monitoring effort than others, and these turtle-hour and dolphin-hour values have not been standardized for this.

Turtle-hours and dolphin-hours equal the number of turtles or marine mammals observed multiplied by the duration of the observation event in hours. Turtle-hours and dolphin-hours are not equivalent to the number of turtles or marine mammals observed. Zero turtle-hours and dolphin-hours indicate no sea turtles or marine mammals were observed by the Platform Removal Observer Program in the lease block during 2007-2014. Also, turtle-hours and dolphin-hours include observations from both surface and aerial monitoring combined.

The Bureau of Ocean Energy Management Outer Continental Shelf blocks are used to define small geographic areas within an Official Protraction Diagram for leasing and administrative purposes.  The total area in a block does not exceed 5,760 acres.    


Maps for turtle-hours and dolphin-hours for both state and federal lease blocks can be accessed from the tabs at the top of the page. Click on any lease block where observations have occurred to view associated turtle-hours or dolphin-hours.

Zooming in by repetitively clicking on the “+” symbol will reveal lease block numbers at higher magnifications.
If the longitude and latitude of the lease block are known it can be easily located by clicking on the image of the magnifying glass, typing in coordinates for longitude and latitude (example: -94.0, 29.0), and clicking “Enter.”

Last updated by Southeast Fisheries Science Center on 06/21/2019