Not all species of seals are endangered, but for the many species that are endangered, there are a number of different causes, including hunting, climate change and natural disasters. The populations of many seal species have been steadily declining over the past several hundred years due to humans killing millions of them for their skin, meat and blubber.

The changing environment and decline in Arctic sea ice due to climate change has also begun wreaking havoc on many seal species, including spotted, bearded, ringed and ribbon seals. Collectively known as ice seals, the decline in sea ice has led to high rates of seal pup mortality, putting many of these species in danger of extinction.

Oil spills, pollution and other human factors have also played a major role in endangering many seal species. New viruses have also decimated the population of some species, such as the Mediterranean monk seal, which lost more than two-thirds of its total population in 1997 due to a virus. Some seal species are also suffering from low genetic diversification, which makes it much harder for them to adapt to changes in their environment.

The Mediterranean monk seals are one of the four most endangered seal species in the world, along with Hawaiian monk seals, Saimaa ring seals and Lacs de Loups Marins harbor seals, also known as Ungava seals.