NEW INFORMATION ON THE NATURAL HISTORY, DISTRIBUTION, AND SKULL SIZE OF THE EXTINCT (?) WEST INDIAN MONK SEAL, MONACHUS TROPICALIS

Abstract

Our knowledge of the extinct West Indian monk seal, Monachus tropicalis, is scant due to heavy exploitation following European colonization of the New World. We present previously unknown accounts of the species, including unpublished field notes of biologist E. W. Nelson, who observed a small number of wild seals in June of 1900. Records indicate that M. tropicalis may have had a long pupping season, occurred in large groups (up to 100) when abundant, probably ate fish and crustaceans, were preyed upon by sharks, and that young and adult seals may have assorted themselves into different age groups when hauled out. Additional records extend the known range of M. tropicalis to include the north coast of South America as far east as Guyana. We also present previously unavailable measurements from a large series of adult skulls and mandibles (n= 48). Two cases of histocytosis X, carcinoma, or other disease of the hard palate are documented from among these specimens.

Biogeography and taxonomy of extinct and endangered monk seals illuminated by ancient DNA and skull morphology

“…Historical population estimates for the species ranged from 233,000–338,000 prior to the catastrophic decline of the species, caused by unrestricted hunting that increased throughout the nineteenth century (McClenachan and Cooper 2008). No well-documented sightings postdate 1952, and the species is widely regarded as extinct (Mignucci-Giannoni and Odell 2001, Adam and Garcia 2003, McClenachan and Cooper 2008). This is the only historical example of a marine mammal extinction in the tropics, and one of few species-level extinctions of marine mammals in the historical period, along with the Steller’s sea cow ( Hydrodamalis gigas , North Pacific, last recorded in 1768), the Japanese sea lion ( Zalophus japonicus , East Asia, last recorded in 1951), and the Yangtze River dolphin or Baiji ( Lipotes vexillifer , Yangtze River of China, probably extinct within the past decade) (Flannery and Schouten 2001, Wolf et al 2007, Turvey 2009, Turvey et al 2007).…”

Extinction rate, historical population structure and ecological role of the Caribbean monk seal

“…Specifically, the model was structured to address the question of how much fish and invertebrate biomass would have been required to support historical monk seal populations. Monk seal population size estimates derived previously were converted to biomass per habitat area using an average biomass of 245 kg for adult and 50 kg for juvenile seals (Adam & Garcia 2003) and a total reef area in the northern Caribbean of 4400 square kilometres (Spalding et al 2001). A food web model was constructed using ECOPATH software and published biomass, productivity and consumption values (Polovina 1984).…”

“…Because the estimate of fecundity is considered low (Adam & Garcia 2003) and hunting at the highest rate of 100 seals per night probably occurred only during peak breeding season, the most conservative estimates of 48 156-69 810 seals in the northern Caribbean were selected. These estimates correspond to a hunting season of 30-45 days and a fecundity rate of 0.2.…”

Prehistoric and historic distributions of the critically endangered Mediterranean monk seal (Monachus monachus) in the eastern Atlantic

“…). One example is the Caribbean monk seal ( Neomonachus tropicalis ), whose extinction was initially attributed exclusively to hunting (Adam and García ). However, the distance of N. tropicalis colonies from the center of its original distribution area (McClenachan and Cooper ), and the low density of its fragmented populations when hunting began (Baisre ) were later added as extinction factors.…”