Histriophoca fasciata

12.

Ribbon Seal

Histriophoca fasciata

French: Phoque rubané / German: Bandrobbe / Spanish: Foca listada

Taxonomy. Phoca fasciata Zimmermann, 1783,

“Wohnt um die Kurilischen Inseln” (= Russia, Kuril Islands).

This species is monotypic.

Distribution. E Siberian, Chukchi, W Beaufort, and Bering seas, and Sea of Okhotsk, and high latitudes of the N Pacific Ocean, from Hokkaido and the N Sea of japan lo Alaska.

Descriptive notes. Total length c.150-175 cm; weight 70-110 kg. Newborns are ¢.90 cm in length and weigh c.10 kg. Ribbon Seals are relatively small, with large eyes and exceptionally striking body coloration. Young Ribbon Seals are uniform color, but a banding pattern begins to develop during the first couple of years oflife. Adult males have broad white bands around their necks, front flippers, and body just in front of pelvis against a dark brown to black background. Adult females have a lighter brown to gray general background and fainter bands. Front flippers of Ribbon Seals are small but have robust, strong claws that appear to be adapted to help them haul-out in fast ice (ice fastened to land) and pack ice.

Habitat. Mostly restricted to the Bering Sea and Sea of Okhotsk, although recent studies have revealed that they range widely into the North Pacific Ocean during spring, summer, and autumn after the breeding season and after the fast ice melts and packice habitats recede. During winter and early spring, Ribbon Seals are mostly found in coastal fast-ice and near-shore, pack-ice habitats off eastern Russia and Japan and in pack-ice habitats of the central Bering Sea and north-western Alaska (USA). As ice melts and recedes, Ribbon Seals appear to be mostly pelagic, roaming over large areas in the Bering Sea, near the Aleutian Islands, into the Beaufort and Chukchiseas, and south into the central North Pacific Ocean.

Food and Feeding. In spring, Ribbon Seals have a relatively diverse diet of shrimp, squid, and fish such as Arctic cod (Boreogadus saida and Arctogadus spp.), saffron cod (Eleginus gracilis), walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus), capelin (Mallotus villosus), and flatfish. OffJapan, walleye pollock can be a primary prey in winter and spring. In a 2008 summary by the US National Marine Fisheries Service, Ribbon Seals were reported, across many studies,to select prey from 20 genera of at least twelve fish families, eight genera from four cephalopod families, and eleven genera of eight crustacean families. They forage relatively deep to 500 m or more.

Breeding. Offspring are born on fast ice or pack-ice floes in March-April and are weaned at ¢.3—4 weeks of age. Nothing is known of the breeding system of the Ribbon Seal, although their sparse distribution during the breeding season suggests they are not polygynous. Adult males do make a variety of underwater noises that have been suggested to be involved with attracting females or repelling other adult males from breeding opportunities. Ribbon Seals are sexually mature at ¢.3-5 years old. Maximum life span is probably 25-30 years.

Activity patterns. There is little specific information available for this species because Ribbon Seals breed in relatively inaccessible pack-ice habitats and then appear to live solitarily in pelagic ocean areas the rest of the year.

Movements, Home range and Social organization. Ribbon Seals appear to be solitary most of their lives and mostly asocial even when they occur in small groups on ice. Recent studies have documented large movements and seasonal migrations of Ribbon Seals throughout the Bering Sea and the Aleutian Islands and into the central North Pacific Ocean.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. Soviet sealers harvested substantial numbers of Ribbon Seals for oil, skins, and food in the Bering Sea from the early 1960s through at least the mid-1990s when quotas were reduced to 10,000-15,000 ind/year because of signs of overharvest and population declines. Native villagers in Alaska and eastern Russia kill a few Ribbon Seals each year, but they are generally inaccessible to them throughout the year. Conservation threats include loss of sea ice from caused by climate change, oil and gas development in the Bering Sea and Sea of Okhotsk, and incidental loss from commercial fisheries. Based on estimates from 1968 to 1990, three separate populations of Ribbon Seals have been proposed associated with aggregations of breeding individuals: Bering Sea with 120,000-140,000 individuals, southern Sea of Okhotsk with ¢.50,000 individuals, and northern Sea of Okhotsk with ¢.320,000 individuals. A 2008 assessment by the US National Marine Fisheries Service suggested a global population of 240,000 Ribbon Seals, and a petition to list it under the US Endangered Species Act was denied in 2013. Nevertheless, the assessment suggested that populations of Ribbon Seals are likely to decline gradually in the foreseeable future, correlated with declining sea ice, which will negatively affect survival and reproduction.

Bibliography. Boveng et al. (2008), Burkanov & Lowry (2008), Burns (1970, 1981), Burns & Fay (1970), Deguchi et al. (2004), Frost & Lowry (1980), Kelly (1988), Lowry & Boveng (2009), Naito & Oshima (1976), Stewart & Everett (1983), Watkins & Ray (1977).