Avoidance or attraction to aerial or shipboard platforms may also influence density estimates, depending on certain species [18], [19].
Datasets from all platforms (shipboard, aerial, shore, and tag) were included.
In addition, observations from other dataset platforms (shipboard, aerial, and shore) were not guaranteed as unique individuals and replicate sightings are possible.
When broken down by platform, however, more shipboard and satellite tag data (records and number of animals sighted) were from non-US contributors.
When broken down by platform, densities of shipboard survey tracks were the highest at around 7.4 km per square km, found near Great Abaco Island, Bahamas (Figure 6a) where high numbers of sea turtles (loggerhead Caretta caretta being the most abundant species) and cetaceans (bottlenose dolphin Tursiops truncatus being the most abundant species) were observed.
Seabirds comprised the greatest number of records, compared to the other two taxa, and most records were from shipboard surveys, compared to the other three platforms.
Although survey observation widths vary among platform types (i.e., aerial, shipboard, shore, and tag), the details of constructing accurate survey strip widths was not available, therefore a common method was applied to all datasets.
For seabirds, all platforms peaked at different SSHs, with shipboard observations in lower waters than aerial observations, followed by satellite tags (Figure 7h, Table 5).
For sea turtles, all platforms also peaked at different SSHs, with shipboard survey data having peaks slightly overlapping with both aerial and tag data (Figure 7i).
"Water taxis, ferries, bum boats and other harbor craft require special concern, because they can serve as an ideal platform for terrorists," the Joint Chiefs of Staff wrote in defining "Shipboard Terrorist Threat Conditions," a copy of which was provided by a United States government official.
