Hawaiian monk seal. A subtropical pinniped that lives primarily in the Hawaiian Islands, its distribution is limited to United States territory. Adult length is about 2.1–2.4 m and weight about 170–240 kg; it prefers to haul out on sandy beaches. It forages mainly at night on benthic fishes, crustaceans, and cephalopods, typically diving to depths within 150 m. Breeding occurs year-round but is most frequent from March to August; the gestation period, including delayed implantation, is about 11 months, and mothers fast while nursing until weaning. After a severe population decline, conservation measures have been implemented; the IUCN lists it as Endangered (EN, formerly IUCN Category I B).