The U.S. National Marine Fisheries Service (NMFS) is required to prepare an annual Stock Assessment Report (SAR) for each marine mammal stock to update abundance, stock structure, maximum net productivity, human-caused mortality, potential biological removal (PBR), and status. In the summer of 2004, the Southeast Fisheries Science Center (SEFSC) conducted a marine mammal survey in the northern Gulf of Mexico (GMx). Operations occurred in the waters from 200 m deep seaward to the Exclusive Economic Zone (EEZ) from Brownsville, Texas east into the Straights of Florida. The survey was designed using ship-based, line-transect methods in which experienced marine mammal observers visually located marine mammals, identified the species (to the lowest taxonomic level possible) and counted the number of whales and dolphins sighted along predetermined tracklines. A sighting constitutes a group of marine mammals (whales and dolphins) seen at the same location and time. This dataset includes marine mammal visual observation data and effort points with surveying conditions that can be used in abundance and density modeling per visual line-transect survey protocols. This dataset also includes opportunistic marine mammal photographs and information on biopsy samples collected during the survey.

As part of the Vessel Surveys for Abundance and Distribution of Marine Mammals and Seabirds (VSAD) project, the Southeast Fisheries Science Center (SEFSC) conducted a shipboard survey of the U.S. oceanic waters of the Gulf of Mexico out to the Exclusive Economic Zone (EEZ) from 2023-06-22 to 2023-08-14. The survey was designed for a two-team independent visual observer approach with distance sampling to estimate the detection probabilities for marine mammal sightings. A sighting constituted a single or group of marine mammals (whales and dolphins) seen at the same location and time. This dataset includes marine mammal visual observation data and effort points with surveying conditions that can be used in abundance and density modeling per visual line-transect survey protocols. This dataset also includes opportunistic marine mammal photographs and biopsy samples, and non-marine mammal sightings (a.k.a. occurrences) such as sea turtles.