The marine mammals of the Gulf of Mexico

Abstract

Recorded knowledge of marine mammals of the Gulf began with commercial whaling of sperm whales, short-finned pilot whales, and Risso’s dolphins in the 1700s and 1800s, progressed to natural history observations and one of the first volunteer stranding organizations, the Texas Marine Mammal Stranding Network, in the 1970s. The vegetarian sirenian, the West Indian manatee (Trichechus manatus), occurs mainly in Florida. All others are cetaceans, members of the whale and dolphin clades. There are no porpoises, sea lions, fur seals, or true seals in the Gulf. The most common cetacean in the Gulf numerically is the pantropical spotted dolphin (Stenella attenuata), and the one with most biomass is the sperm whale (Physeter macrocephalus), common in mid-depth waters off Louisiana and the shelf break off Texas. Major anthropogenic threats exist for all marine mammals but do not appear to be as intensive in the Gulf as in several other oceanic basins. Threats to marine mammals in the Gulf include prey depletion, incidental mortality, injury due to fisheries, intentional and direct takes, vessel strikes, disturbance, acoustic (noise) pollution, chemical contamination, ingestion of solid debris, oil spills, and aspects of ecosystem change.