GoMMAPPS Winter aerial abundance survey from Jan – Mar 2018: Summary Report

As part of GoMMAPPS, the Southeast Fisheries Science Center conducted aerial surveys of continental shelf waters (up to the 200-m isobath) in the U.S. Gulf of Mexico. The survey was conducted between 18 January and 14 March 2018 aboard a NOAA Twin Otter aircraft at an altitude of 600 feet (183 m) and a speed of 100-110 knots(185-204 kph). Survey tracklines were oriented perpendicular to the shoreline and latitudinally spaced 20 km apart. The survey was designed for analysis using Distance sampling with a two-team (independent observer) approach to correct for perception bias in resulting abundance estimates. A total of 8,158 km of trackline were surveyed on effort. Marine mammal records totaled 201 sightings, including two species of cetaceans and one sirenian. Over 97% of the sightings were of common bottlenose dolphins, followed by Atlantic spotted dolphins. Sea turtles totaled 829 sightings of five different species, although over 50% of the sightings were of turtles that could not be identified to species, only classified as “Hardshell.” The data collected during this survey will be analyzed to estimate the abundance and spatial distribution of marine mammals and sea turtles in the U.S. Gulf of Mexico.

The goal of the survey was to conduct line-transect surveys using the Distance sampling approach to estimate the abundance and spatial distribution of marine mammals and sea turtles in waters over the continental shelf in the U.S. Gulf of Mexico.