The distribution and abundance of marine mam- mals along the United States coast of the Gulf of Mexico are well-documented, but similar studies for the Mexican coast of the Gulf of Mexico are lacking. Furthermore, these animals are...
moreThe distribution and abundance of marine mam- mals along the United States coast of the Gulf of Mexico are well-documented, but similar studies for the Mexican coast of the Gulf of Mexico are lacking. Furthermore, these animals are important indicators of the marine ecosystem health, and sci- entific research is needed to develop appropriate conservation strategies. Thus, the objective of this study was to determine the diversity, distribution, and relative abundance of marine mammals in the northern coasts of Veracruz, Mexico. Boat-based surveys and aerial surveys were carried out from March 2005 to August 2006. The following spe- cies were observed: bottlenose dolphins (Tursiops truncatus), spotted dolphin (Stenella attenu- ata), spinner dolphin (S. longirostris), rough- toothed dolphin (Steno bredanensis), pilot whale (Globicephala macrorhynchus), and an uniden- tified species of a dolphin. Also, the remains of a sperm whale (Physeter macrocephalus) and a humpback whale (Megaptera novaeangliae) were observed. The Margalef Diversity Index showed a value of 1.82 for the entire study area. There were differences in the species sightings across seasons. The abundance for the entire study area was 10,824 (%CV 25.05); the density was 1.45 cetaceans/km2 (%CV 25.05), and the cluster den- sity was 0.71 cetaceans/km2 (%CV 15.25). The dry season showed a relative abundance of 1.98 cetaceans/h; the rainy season, 1.07 cetaceans/h; and the cold front season, 1.28 cetaceans/h. This is a first glimpse of cetacean population sizes in Mexico. Mexican authorities consider all marine mammal species to be under some conservation status, but they do not have population estimates. Supplementary studies will extend the information presented here for further refinement of cetacean diversity and distribution in Mexican waters of the Gulf of Mexico. Special effort is needed in deeper waters of the Mexican part of the Gulf of Mexico since there is no information about diversity and abundance of marine mammals for those areas.
