Ribbon Seal, Histriophoca fasciata
The ribbon seal (Histriophoca fasciata) is a true seal within the family Phocidae that can be found in the North Pacific Sea. It prefers a habitat in arctic and subarctic areas like the Sea of Okhotsk and the Bering Sea. As is typical to seal species, it will leave the water during the winter and spring months, where it will remain on pack ice to breed, birth pups, and molt. For the rest of the year these seals will live in open water, although some will occasionally move north as the ice recedes. Although this species is not often found far south, one individual was spotted near Seattle and another near Morro Bay in California.
The ribbon seal is medium sized, reaching an average body length of 5.2 feet and an average weight of 209 pounds. This species is black in color, with four thick white stripes along the body. This coloring is typically seen in males, while the coloring in females can vary in brightness. Pups are pure white in color, with soft fur. After this baby fur is molted, the pups become blue gray in color with a silvery underbelly, eventually growing into adult coloring. Both males and females have an inflatable air sac that is attached to the trachea, although this grows larger in males, and it is thought to be used to enhance mating calls underwater.
With the exception of mating season, the ribbon seal is solitary. The mating season occurs during the months of April to May. Pregnant females give birth on the pack ice and nurse the pups for up to one month. After this period, pups will leave their mothers but remain on the ice with the other seals, losing their baby fur to adult fur before leaving for open waters. Males reach sexual maturity at three to six years of age, while females can breed earlier at two to five years of age.
The diet of the ribbon seal consists of pelagic species, like fish, and cephalopods like octopuses and squid. Young individuals will also consume crustaceans. Both adult and recently weaned seals will dive to depths of 656 feet in search of food. This species can fall prey to orcas, polar bears, and Pacific sleeper sharks.
The ribbon seal has been threatened by hunting in the past, because young individuals strongly resemble young harp seals. However, the ribbon seal was not killed as often because it does not gather in herds. In 1969, hunting of the ribbon seal was limited by the Soviet Union and its population numbers have grown to about 250,000.The United States agreed to study this species in Alaska in hopes of placing it on the endangered species list, but it was found that depleting ice levels did not affect the seals in that area. As a result, the ribbon seal was listed as a U.S. National Marine Fisheries Service (NMFS) Species of Concern. The NMFS and the National Oceanic and Atmospheric Administration have concerns about the status of this species, but more information is needed to place it in the US Endangered Species Act. The ribbon seal currently appears on the IUCN Red List with a conservation status of “Vulnerable.”
Image Caption: Rare adult male ribbon seal. Russia, Ozernoy Gulf. Credit: Michael Cameron, NOAA/NMFS/AKFSC/NMML/Wikipedia