Histriophoca fasciata 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Carnivora Phocidae

Scientific Name: Histriophoca fasciata (Zimmerman, 1783)
Common Name(s):
English Ribbon Seal
Phoca fasciata Zimmermann, 1783
Taxonomic Notes: The Ribbon Seal was originally placed in the genus Phoca by Zimmerman (1783), but later it was listed as Histriophoca by Gill (1873) and Scheffer (1958). The taxonomy of northern phocids was reviewed by Burns and Fay (1970) and they returned Ribbon Seals to Phoca based on cranial morphology. More recently, molecular genetics studies (Árnason et al. 1995, Higdon et al. 2007) have shown that Ribbon Seals belong in the separate genus, Histriophoca, and thus Histriophoca fasciata is the currently accepted scientific name (Rice 1998, Committee on Taxonomy 2014).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2015-06-09
Assessor(s): Lowry, L.
Reviewer(s): Boveng, P.
Facilitator/Compiler(s): Ahonen, H., Pollock, C.M., Chiozza, F. and Battistoni, A.
Despite recent progress in population assessment, estimates of total abundance of Ribbon Seals are imprecise and current population trend is not known. But, with modern assessment methods producing an estimate of nearly 400,000 animals it is evident that the population is quite large. Commercial harvesting of Ribbon Seals stopped in 1994 and numbers have likely been growing since then. The only major threat identified is climate change, and effects of that are not likely to occur in the near future. Ribbon Seals are classified as Least Concern.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Ribbon Seals inhabit the northern North Pacific Ocean and adjoining seas, and are seen most commonly in the Bering and Okhotsk seas hauled out on sea ice in the ice front region. They are seen on ice until it has melted in May-June, and seldom haul out on ice or land until the following spring (Burns 1981). The presumption that they live a pelagic lifestyle during summer and fall has been corroborated by tracking with satellite-linked tags (Boveng et al. 2013). Results from tagging and occasional sightings indicate that during the ice free months they range from Hokkaido and the northern Sea of Japan, eastward through the northern North Pacific and Aleutian Islands to the western Gulf of Alaska, and northward through the Chukchi Sea to the East Siberian Sea, the western Beaufort Sea, and the Arctic Ocean (Moore and Barrowclough 1984, Mizuno et al. 2002, Boveng et al. 2013). Single Ribbon Seals occasionally occur along the coast of North America and Asia outside of their normal range (Boveng et al. 2013), and a debilitated vagrant was found on the beach in Morro Bay, California, and taken into captivity (Roest 1964).
Countries occurrence:
Japan; Russian Federation; United States
FAO Marine Fishing Areas:
Arctic Sea; Pacific – northwest; Pacific – northeast
Additional data:
Estimated area of occupancy (AOO) - km2:8107100Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:13080007
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):3Lower depth limit (metres):600
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Three separate populations of Ribbon Seals have been proposed associated with aggregations of breeding animals - the Bering Sea, the southern Sea of Okhotsk, and the northern Sea of Okhotsk (Fedoseev 2002). However, Boveng et al. (2013) considered the biological evidence for separate breeding populations in the Okhotsk and Bering seas to be weak or equivocal, and they assessed the status of Ribbon Seals as a species with a single population.

Ribbon Seals are difficult to enumerate, as they are widely dispersed over large areas that are generally far from land. Nonetheless, a number of population estimates have been proposed based on counts made during aerial surveys flown over sea ice in the Bering and Okhotsk seas (see Boveng et al. 2013). In most cases surveys were not designed specifically for Ribbon Seals, and the methods used varied and were often not well described. Burns (1981) reported a population estimate of 90,000-100,000 animals in the Bering Sea, and 140,000 animals in the Okhotsk Sea. Fedoseev (2002) gave an estimate of 120,000 to 140,000 animals for the Bering Sea in 1987 and estimates of between 200,000 (1968-1974) and 630,000 (1988-1990) for the Okhotsk Sea. The Okhotsk Sea population was reported to have averaged 370,000 animals with 320,000 in the central northwestern region and 50,000 in the southern region, in the period between 1968 and 1990 (Fedoseev 2002). Little information was collected on Ribbon Seal abundance between 1991 and 2007. Boveng et al. (2008) used eastern and central Bering Sea survey results from 2007, combined with information on distribution (Fedoseev 1973, Fedoseev et al. 1988), to estimate the range-wide abundance of Ribbon Seals as 267,000. The 95% credible interval for that estimate was 154,000-827,000.

American and Russian scientists conducted image-based aerial surveys of ice-associated Seals in the Bering and Okhotsk seas in 2012 and 2013. Data from those surveys are not yet fully analyzed, but using a limited subsample of the data collected from the U.S. portion of the Bering Sea in 2012, Conn et al. (2014) estimated about 184,000 (95% CI: 145,752-230,134) Ribbon Seals in that area. The estimate from the 2013 survey in the Okhotsk Sea was 181,179 (95% CI: 118,392–316,995) Ribbon Seals (Chernook et al. 2014). The mean estimate from the two surveys combined is about 365,000 animals.

Population trend is unknown.
Current Population Trend:Unknown
Additional data:
Number of mature individuals:183000Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Ribbon Seals are medium sized phocids, with a striking pattern of light bands on their darker pelage. Pups at birth are about 86 cm long and weigh about 9.5 kg. Males and females are similar in size with adults typically 150-175 cm long, and weighing 70-90 kg (Tikhomirov 1968, Burns 1981, Fedoseev 2000).

Female Ribbon Seals mature when they are 2-4 years old and males when they are 3-5 years. Adult females give birth to a single white-coated pup in March-May that is nursed for 3-4 weeks. Clean, white, broken pack ice is preferred as a birth site over solid ice sheets and ice with sediment or algae. Breeding occurs after the pup is weaned, and gestation lasts about 9 months after 2-2.5 months of delayed implantation. Ribbon Seals generally live to about 20 years old, but maximum longevity may be as much as 30 years (Burns 1981, Boveng et al. 2013).

From late winter until summer, Ribbon Seals occupy the pack ice that overlies the continental shelf. They prefer areas of 60-80% ice coverage, rarely use shore fast ice, and do not haul-out on land unless moribund (Kelly 1988, Burns 1981). They typically lie away from the edge of floes and show little concern for the approach of people or vessels. Broken pack ice is preferred over solid ice sheets and highly concentrated pack ice. Their whereabouts when pack ice breaks up or disappears from the Bering Sea and the Sea of Okhotsk is not well known. Kelly (1988) suggested that animals from the Bering Sea population summer in the Chukchi Sea and those from the Sea of Okhotsk, where Ribbon Seals are not seen after mid-July, might move into the southern Bering Sea. Burns (1981) reported that few Ribbon Seals are seen on ice or harvested by Alaska Natives in the Bering Strait and Chukchi Sea after mid-June, and suggested that many Ribbon Seals are probably pelagic during summer and fall, not hauling out on land or ice until the next winter.

Satellite-linked tags were applied to more than 80 Ribbon Seals captured in spring 2005-2010 in the ice of the central and western Bering Sea (Boveng et al. 2013). All tagged Seals were pelagic during summer and fall. They ranged widely through the Aleutian Islands, Bering Sea, Bering Strait, Chukchi Sea, and adjacent Arctic Basin. Ribbon Seals from the Okhotsk Sea have not been tagged and tracked.

The overall diet of Ribbon Seals is unknown because essentially all the samples that have been examined came from the spring period when the primary activities are pupping, breeding, and molting, and most stomachs are empty. Prey items identified from spring samples included at least 25 species of fishes and 23 species of invertebrates. Commonly occurring prey included Walleye Pollock, Arctic Cod, Pacific Cod, Saffron Cod, Capelin, Smooth Lumpsucker, Eelpout, flatfish, Squids, Octopus, and crustaceans. Crustaceans (Euphausiids and Shrimps) appear to be a main food item for newly weaned and young Seals (Boveng et al. 2013). Using both stomach contents and stable isotope analysis, Dehn et al. (2007) concluded that trophic level of the Ribbon Seal diet increased with age of the Seal, suggesting a diet transition from mostly crustaceans in young animals to fish and nektobenthos in older animals. The only two stomach samples collected in mid-winter contained Walleye Pollock and Arctic Cod (Burns 1981).

Dive data provided by satellite-linked tags showed relatively shallow diving (mostly to <100 m) during spring when Seals are over the continental shelf, with deeper diving occasionally to >600 m at other times when the Seals may be over deep basins (Boveng et al. 2013).
Generation Length (years):10.4
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: Russian commercial hunting of Ribbon Seals began in the Okhotsk Sea in the 1930s and expanded to an annual harvest of 20,000 in the 1950s (Heptner 1996). The annual harvest averaged 11,000 from the 1950s to 1969 and 5,000-6,000 from 1969-1992 (Fedoseev 2002). Commercial hunting began in the Bering Sea in 1961 with an average annual harvest of 9,000 through 1968, declining to 3,000 to 4,000 per year from 1969 to 1992 (Heptner 1996). Reported harvests did not include the number of animals that were killed but lost which may have amounted to 15-20% (Fedoseev 2000). Commercial hunting from sealing vessels stopped in the Bering Sea in 1991 and in the Okhotsk Sea in 1994 because of economic factors, but substantial quotas were still allocated at least through 2005 (Boveng et al. 2013).

Ribbon Seal abundance appears to have declined due to the intensive commercial hunting in the late 1950s and 1960s, but began to rebound after quotas were reduced in 1969 (Burns 1981, Boveng et al. 2013).
The number of Ribbon Seals taken by indigenous hunters for subsistence is not well quantified, but harvests are low and almost certainly sustainable (Boveng et al. 2013).

Threats [top]

Major Threat(s): Ribbon Seals are sometimes incidentally caught in commercial fisheries, but bycatch data are incomplete. Available data suggest a take of approximately one per year by the Alaska fisheries that were monitored during 1990-2007 (Boveng et al. 2013). Woodley and Lavigne (1991) reported catches of a few up to 14 per year in fisheries around Japan. During seven years (1993-1999) of monitoring the offshore salmon gill net fishery in Russian Far East, incidental mortality of Ribbon Seals was estimated to be 1,079 individuals (154 per year), mostly juveniles (Burkanov and Nikulin 2001). These data certainly underestimate the total take as bycatch is not monitored in a number of Russian and Alaskan fisheries.

Commercial fisheries target a number of known Ribbon Seal prey species (e.g., Walleye Pollock, Pacific Cod, Pacific Herring, and Capelin), and it is possible that reductions in prey biomass caused by fishing could have an impact on Seal nutrition. At the current time, biomasses of these fishes are fairly high and stable, at least in the Bering Sea, and impacts of removals on Ribbon Seal nutrition are not likely. This situation could change, however, as fishing patterns shift with warming waters and reduced sea ice (Boveng et al. 2013).

As is true for all ice-associated pinnipeds, climate warming and reductions in seasonal sea ice are likely to have impacts on Ribbon Seals. A detailed review of this issue by Boveng et al. (2013) analyzed the possible individual and cumulative effects on Ribbon Seals of future warmer temperatures, reduced ice, ocean acidification, and associated changes in prey, predators, parasites, and diseases. They concluded that while impacts are likely at some point in the future, they are very difficult to predict or quantify.

Conservation Actions [top]

Conservation Actions: Russia stopped large scale commercial harvesting of Ribbon Seals in 1994. Shore-based harvests for subsistence purposes are at very low levels and not likely to be a threat to the population. In the US, Ribbon Seals are protected under the Marine Mammal Protection Act. In 2007, the US National Marine Fisheries Service was petitioned to list the Ribbon Seal as threatened or endangered under the US Endangered Species Act. In 2013 the agency concluded that such a listing was not appropriate at that time (NMFS 2013).

Citation: Lowry, L. 2016. Histriophoca fasciata. The IUCN Red List of Threatened Species 2016: e.T41670A45230946. . Downloaded on 24 September 2018.
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