Current estimates for Hawaiian monk seal (Monachus schauinslandi) populations are about 1,100 animals. Sadly, even this low number puts them far above the other two species of monk seals. Hawaiian monk seals are found solely in the U.S. around the Hawaiian Islands. Most of the Hawaiian monk seals live in the northwestern Hawaiian Islands, although more are being seen in the main Hawaiian Islands.
Hawaiian monk seals are born black but grow lighter as they age. Females are slightly larger than males. Despite this, one issue for females is aggressive males. Some breeding colonies have a high male-female sex ratio, and over-eager males sometimes mob females, leading to injury or death.
Current threats to Hawaiian monk seals include human interactions such as disturbances from humans on beaches, entanglement in marine debris. But threats also include low genetic diversity, disease and male aggression toward females. Much is being done to study and protect the remaining 1,000 or so Hawaiian monk seals, including studying individuals and populations, removing marine debris from habitat to lessen the potential for ingestion or entanglement, and relocating males to other breeding colonies.
The Mediterranean monk seal (Monachus monachus) is even more endangered than the Hawaiian monk seal. This seal once lived throughout the Mediterranean and along the western coast of Africa. Today, the largest numbers of Mediterranean monk seals can be found in Greece, and there are two main populations - a group in the northeastern Mediterranean that lives in the Aegean and Ionian Seas around Greece and Turkey, and a group in the northeastern Atlantic Ocean that lives along the coast of Mauritania and Western Sahara in North Africa. Estimates for the population size of Mediterranean monk seals are less than 600.
Mediterranean monk seals are born dark with a white belly patch. As they grow older, males develop a black coloration with a white belly patch, while females are gray or brown with a light underside. Many Mediterranean monk seals have retreated to caves for protection, especially while pupping, which may lead to early death for some pups if seas are rough. However, in 2010, a colony of Mediterranean monk seals in Greece were discovered. These seals are in a location remote enough that they feel safe enough to haul-out on sandy beaches, so scientists were attempting to keep the location secret to protect the seals.
Current threats to Mediterranean monk seals include coastal development, which decreases seal habitat and increases disturbance from humans, fishermen and fish farm operators, who kill them because of a perceived threat to the fisheries, entanglement in fishing gear, limited food supply, and disease. Efforts to save Mediterranean monk seals include establishing marine reserves and studying seal populations and behavior.
3. Caribbean Monk Seal (Monachus tropicalis)
The Caribbean monk seal (Monachus tropicalis) has the sad distinction of being the first seal species to go extinct because of humans. Although the last Caribbean monk seal was seen in 1952 between Jamaica and Honduras, it was not officially declared extinct until 1996 by the IUCN Red List and 2008 by NOAA.
Caribbean monk seals once lived throughout the Caribbean Sea, Gulf of Mexico and in the western Atlantic Ocean. During this time, according to U.S. Fish and Wildlife Service, there were between 233,000-338,000 seals among 13 different colonies. The seals hauled-out on sandy beaches and were easily visible to colonists from Europe, who killed them for oil and meat. Large numbers were, ironically, killed for scientific research. Others were brought into captivity for scientific display. Hopefully, lessons taught by our treatment of the Caribbean monk seal will help save the Hawaiian and Mediterranean monk seals before they also go extinct.