|Scientific Name:||Histriophoca fasciata|
|Species Authority:||Zimmerman, 1783|
Phoca fasciata Zimmermann, 1783
|Taxonomic Notes:||The Ribbon Seal was originally placed in the genus Phoca by Zimmerman (1783), though 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. Most recently, Ribbon Seals have been called Histriophoca by Muizon (1982), Rice (1998) and Wozencraft (2005).|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor/s:||Burkanov, V. & Lowry, L. (IUCN SSC Pinniped Specialist Group)|
|Reviewer/s:||Kovacs, K. & Lowry, L. (Pinniped Red List Authority)|
Ribbon Seals have an unknown mortality in salmon nets and bottom-set gill nets. This species is likely to be seriously, negatively impacted by reductions in the extent and seasonal coverage of sea ice throughout their range. However, it is not possible to evaluate the current situation for this species as the most recent estimates are almost two decades old. This species must be considered Data Deficient at this time.
IUCN Evaluation of the Ribbon Seal, Histriophoca fasciata
Prepared by Pinniped Specialist Group
A. Population reduction Declines measured over the longer of 10 years or 3 generations
A1 CR > 90%; EN > 70%; VU > 50%
Al. Population reduction observed, estimated, inferred, or suspected in the past where the causes of the reduction are clearly reversible AND understood AND have ceased, based on and specifying any of the following:
(a) direct observation
(b) an index of abundance appropriate to the taxon
(c) a decline in area of occupancy (AOO), extent of occurrence (EOO) and/or habitat quality
(d) actual or potential levels of exploitation
(e) effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.
The generation time of Ribbon Seals is probably about 10 years. The most recent population abundance estimate, based on aerial surveys conducted in 1979, was between 450,000 and 500,000 with an increasing trend. No reliable surveys have been conducted since 1979 and current abundance and trend are unknown. A decline in Ribbon Seals in the Bering Sea was observed in mid-late 1960s due to overharvesting. After reduction of harvest effort the population recovered rapidly. Large scale commercial harvests of ribbon seals in the Russian Far East ceased in 1994.
A2, A3 & A4 CR > 80%; EN > 50%; VU > 30%
A2. Population reduction observed, estimated, inferred, or suspected in the past where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.
A population reduction of Ribbon Seals has not been observed, estimated, inferred, or suspected in the past 30 years.
A3. Population reduction projected or suspected to be met in the future (up to a maximum of 100 years) based on (b) to (e) under A1.
A population reduction of Ribbon Seal is suspected in the future due to global warming and rapid reduction of sea ice habitat essential for pupping and moulting. If global warming continues it is likely that the population of ribbon seals will decline by at least 30% within next 30 years which qualifies the species for listing as vulnerable under criterion A3c.
A4. An observed, estimated, inferred, projected or suspected population reduction (up to a maximum of 100 years) where the time period must include both the past and the future, and where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under Al.
The cause of the Ribbon Seal decline in the 1960s-1970s was understood and reversible. No other population reduction of ribbon seal has been observed, estimated, inferred, or suspected in the past.
B. Geographic range in the form of either B1 (extent of occurrence) AND/OR B2 (area of occupancy)
B1. Extent of occurrence (EOO): CR < 100 km²; EN < 5,000 km²; VU < 20,000 km²
The EOO of Ribbon Seal is > 20,000 km².
B2. Area of occupancy (AOO): CR < 10 km²; EN < 500 km²; VU < 2,000 km²
The AOO of Ribbon Seal is > 2,000 km².
AND at least 2 of the following:
(a) Severely fragmented, OR number of locations: CR = 1; EN < 5; VU < 10
(b) Continuing decline in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and/or quality of habitat; (iv) number of locations or subpopulations; (v) number of mature individuals.
(c) Extreme fluctuations in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) number of locations or subpopulations; (iv) number of mature individuals.
C. Small population size and decline
Number of mature individuals: CR < 250; EN < 2,500; VU < 10,000
The number of mature ribbon seals is > 10,000.
AND either C1 or C2:
C1. An estimated continuing decline of at least: CR = 25% in 3 years or 1 generation; EN = 20% in 5 years or 2 generations; VU = 10% in 10 years or 3 generations (up to a max. of 100 years in future)
C2. A continuing decline AND (a) and/or (b):
(a i) Number of mature individuals in each subpopulation: CR < 50; EN < 250; VU < 1,000
(a ii) % individuals in one subpopulation: CR = 90–100%; EN = 95–100%; VU = 100%
(b) Extreme fluctuations in the number of mature individuals.
D. Very small or restricted population
Number of mature individuals: CR < 50; EN < 250; VU < 1,000 AND/OR restricted area of occupancy typically: AOO < 20 km² or number of locations < 5
The number of mature Ribbon Seals is > 1,000. AOO is > 20 km² and the number of locations is > 5.
E. Quantitative analysis
Indicating the probability of extinction in the wild to be: CR > 50% in 10 years or 3 generations (100 years max.); EN > 20% in 20 years or 5 generations (100 years max.); VU > 10% in 100 years
There has been no quantitative analysis conducted on probability of extinction of Ribbon Seals.
Listing recommendation — Ribbon Seals have an unknown mortality in salmon nets and bottom-set gill nets. This species is likely to be seriously, negatively impacted by reductions in the extent and seasonal coverage of sea ice throughout their range. However, it is not possible to evaluate the current situation for this species as the most recent estimates are almost two decades old. This species must be considered Data Deficient at this time.
|Range Description:||Ribbon seals inhabit the Bering, Chukchi, and Okhotsk seas and high latitudes of the western and central North Pacific Ocean (Stewart 1983), from Hokkaido and the northern Sea of Japan (Mizuno et al. 2002) north and offshore to the East Siberian Sea in the Russian Federation to the western Beaufort Sea (Moore and Barrowclough 1984) and south to the Alaska Peninsula in the United States (Angliss and Outlaw 2005). A sub-adult was killed near Cordova Alaska (Burns 1981), a debilitated vagrant was found beached in Morro Bay California (Roest 1964) and an adult has been observed in the Tsushima Strait (Heptner 1996).|
Native:Japan; Russian Federation; United States
|FAO Marine Fishing Areas:||
Arctic Sea; Pacific – northeast; Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|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, the species has a continuous distribution and no morphological differences are known. Burns (1981) reported a population estimate of 90,000-100,000 animals in the Bering Sea, and 140,000 animals in the Sea of Okhotsk. Fedoseev (2002) gives an estimate of 120,000 to 140,000 animals for the Bering Sea in 1987 and estimates between 200,000 (1968-1974) and 630,000 (1988-1990) for the Sea of Okhotsk. The Sea of Okhotsk population averaged 370,000 animals with 320,000 in the central northwestern population and 50,000 in the southern population, in the period between 1968 and 1990 (Fedoseev 2002). The most recent reliable aerial survey of ribbon seal was conducted in 1990 (Fedoseev 2005). The population appeared to be increasing at that time. The current abundance and trend are unknown.|
|Habitat and Ecology:||
Ribbon seals occupy the pack ice that overlies deeper water near the continental shelf break out, from late winter until summer. 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, as ribbon seals can only open and maintain access holes in ice up to approximately 15 cm thick. Their whereabouts when pack ice breaks up or disappears from the Bering Sea and the Sea of Okhotsk is not well known and is the subject of conflicting opinions. Kelly (1988) suggests that animals from the Bering Sea population summer in the Chukchi Sea and those from the Sea of Okhotsk, which has no ribbon seals by mid-July, might move into the southern Bering Sea. Burns (1981) says that few ribbon seals are seen on ice or harvested by Alaska Natives in the Bering Strait and Chukchi Sea after mid-June. Many ribbon seals are probably pelagic during the fall, not hauling out on land or ice, until the next winter (Burns 1981).
Ribbon seals are solitary for much of their lives. Pups are born on ice floes from early April to early May. Clean, white, broken pack ice is preferred over solid ice sheets and ice with sediment or algae. Ribbon seals maintain access holes in ice up to approximately 15 cm thick, and can often be seen in the middle of large floes. Ribbon seals are able to move rapidly on ice, using slashing side-to-side motions. They also extend their necks to peer at sources of disturbance, but are fairly approachable by boat. They are rarely encountered, because of the remote and inhospitable nature of their habitat.
Diet varies by area and age of the seal. Ribbon seals in the Okhotsk and Bering seas are known to take 35 different species of fish and invertebrates (Frost and Lowry 1980, Bukhtiyarov 1986). Young ribbon seals feed on euphausiids after weaning and until about age one when they switch to feed predominantly on shrimp for a year. As two-year-olds they take up the adult diet, which includes a variety of fishes, squids, and octopuses. Bukhtiyarov (1986) has determined that diet biomass of ribbon seals in the Sea of Okhotsk contains 69% of pollock, while in the Bering Sea 67% was squid and octopuses.
Females are mature when they are 2-4 years old and males when they are 3-5 years (Burns 1981). The annual pregnancy rate of adult females is 85%. Gestation lasts 9 months after 2-2.5 months of delayed implantation. Ribbon seals may live up to 26-27 yrs. First year mortality is 44% and the annual mortality rate for older age classes averages 11%.
Russian commercial hunting began in the Sea of Okhotsk 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 (Fedoseev 2002). The average annual harvest in the Sea of Okhotsk from 1969-1992 was 5,000-6,000 (Fedoseev 2002). Commercial hunting began in the Bering Sea in 1961 with an average annual harvest of 9,000 up to 1969, declining to 3,000 to 4,000 per year from 1969 to 1992 (Heptner 1996). Commercial hunting from sealing vessels stopped in the Bering Sea in 1991 and in the Sea of Okhotsk in 1994.
The Bering Sea population appears to have declined shortly after the beginning of commercial hunting in 1961. The average age of harvested animals declined from 9.8 years in 1961, to 6.9 in 1962, and 4.9 in 1963. During the same period, the number of ribbon seals killed per day dropped regardless of hunting conditions (Heptner 1976). After the harvest was limited, abundance of the species quickly recovered.
Interactions between ribbon seals and fisheries are not well documented. There were no mortalities recorded in required logbooks or by voluntary reports from 1990 to 1995 in fisheries monitored by the United States. Estimated mortality from 1999 to 2003 was 1 ribbon seal in the Bering Sea pollock trawl fishery, and 1 observed and 3 estimated mortalities in the Bering Sea/Aleutian Islands Pacific cod longline (Anglis and Outlaw, 2005). During seven years (1993-1999) of monitoring the offshore salmon gill net fishery in Russian Far East, accidental mortality of ribbon seal was estimated to be 1,079 individuals (154 per year), mostly juveniles (Burkanov and Nikulin 2001). Some mature animals die in a bottom gill net halibut fishery in the Sea of Okhotsk, but information is very limited.
Reduction in late winter and spring sea ice cover in the Sea of Okhotsk, or the central and southern Bering Sea could be problematic for ribbon seal reproduction as this species depends on the availability of offshore pack ice. Disruption or alteration of the patterns of Arctic primary productivity and abundance of key marine mammal prey species such as Arctic cod could also have detrimental effects on ice dependent seals (Tynan and DeMaster 1997). Pollock are an important spring ribbon seal food in the central and south central Bering Sea (Frost and Lowry 1980) and in the Sea of Okhotsk (Bukhtiyarov 1986). The effect of pollock harvesting on ribbon seals in the Bering Sea has not been examined, but competition with fisheries has been suggested as a possible limiting factor on population growth, or a threat that could result in declines (Reijnders 1993).
|Conservation Actions:||Russia stopped large scale commercial harvesting of ribbon seals in 1994. Current shore-based harvests in the Russian Far East are at very low levels and not likely to be a threat to the population. No other specific conservation measures are in effect in Russia. In the United States, ribbon seals are protected under the Marine Mammal Protection Act. As of March 2008, a petition for listing ribbon seals under the Endangered Species Act is under consideration by the U.S. Department of Commerce, NOAA Marine Fisheries Service.|
|Citation:||Burkanov, V. & Lowry, L. (IUCN SSC Pinniped Specialist Group) 2008. Histriophoca fasciata. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 13 December 2013.|
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