MARINE MAMMAL SCIENCE, 13(1):157-163 (January 1997) 0 1997 by the Society for Marine Mammalogy
A REVIEW OF THE DISTRIBUTION AND ABUNDANCE OF HARBOR SEALS, PHOCA VITULInA, ON SVALBARD,
NORWAY, AND IN THE BARENTS SEA
Harbor seals (Phoca vitulina) inhabit temperate, subarctic, and some arctic waters of the North Atlantic and North Pacific Oceans, giving them one of the widest distributions of any pinniped (Bigg 1981). Harbor seals inhabiting the Arctic do not keep open breathing holes in the fast ice but are found in areas with access to open water throughout the winter (Mansfield 1967). At Svalbard and in the Barents Sea, harbor seals are at the northern edge of their range (Fig. 1). They are distributed along the western coasts of Svalbard as far north as 78 (Presterud and Gjertz 1990) but have been recorded even farther north at 80 (Rome, and Schaudinn 1900). In the Barents Sea, harbor seals have been found as far east as Novaja Zemlja (Smirnov 1903), but they are not common there. Along the Murman coast in Russia they are considered rare and probably do not occur in the White Sea (Knipowitsch 1908, Kondakov 1992). According to Henriksen and Haug (1994) and Hen- riksen (1995), harbor seals are found in most coastal areas of Finnmark county, north Norway. The aims of the present study were to (1) determine the present distribution of harbor seals in Svalbard and the Barents Sea, and (2) count the minimum number of harbor seals found in these areas during the breeding period in 1990.
In coastal areas of Murman, Finnmark, and Svalbard (Fig. l), surveys were carried out on foot or from inflatable boats. The surveys were conducted during the breeding season between 26 June and 12 July 1990 (see Bigg 1981,
158 MARINE MAMMAL SCIENCE, VOL. 13, NO. 1, 1997
\/ / ho I I
Figure 1. The Barents Sea. (the numbers refer to the numbers and names in Ta- ble 1).
Thompson and Harwood 1990, Temte et al. 1991), and all counts were made at low tide (see Venables and Venables 1960, Roen and Bjorge 1995). On Svalbard and in Finnmark all the colonies were surveyed two to three times, except the two northernmost colonies on Svalbard, which were surveyed only once (27 June). In Murman the seals were counted twice. In colonies which were counted more than once, we used the peak number of seals observed as
NOTES 159
Table 1. Results from counts of harbor seals in Finnmark (Norway), Murman (Rus- sia) and Svalbard (Norway) in the breeding period (June/July) 1990.
Region Total No.
number Pups Date of survey
A. Finnmark 1. Kongsfjord 2. Tanafjord 3. Laksefjord 4. Porsangerfjord 5. Sfm5y
Between sites Total
B. Murman coast 6. Ivanovskaya (rocks) 7. Ivanovskaya (islet)
Between sites Total
C. Svalbard 8. Soroya, Forlandsoyane 9. Skarvnesbukta
10. Havsnes 11. Skjernes 12. Skurvodden 13. Gjelet 14. Selneset 15. Fuglehuken E
Between sites Total
Total all areas (A + B + C)
86 2
10 32 14
221
24 12 3
:
4: 16 June-12 July
16 4 31 8
5 17 28 June-29 June
78 24 26 29 Ii 52 12 19 4
135 33 16 2 12 0 11 2
378 84 14 June-4 July
661 148 16 June-12 July
the minimum size of the population. The seals were counted using binoculars and telescopes. Relevant information from the literature was used to map their distribution. The results are given in Table 1.
Harbor seals were very abundant in Finnmark in the 19th century (Collett 1912). Notably in the 1820s 240 harbor seals were killed in the Tana River (Fig. 1) during eight days, and in the beginning of the 20th century some trappers were known to kill 50-100 seals a year in the Tana River estuary. @ynes (1964) reported large harbor seal colonies around @roya (Fig. 1) before 1940, but that only a few remained in the 1960s. He also reported that the areas west of Nordkapp (the North Cape) were known from ancient times as good places for harbor seal hunting. Neither the harbor seal colonies on Soroya nor the colonies farther north seem to have recovered during the past 50 yr (Q)ynes 1964, Henriksen et al. 1993, Henriksen and Haug 1994). Based on interviews and questionnaries, @ynes (1964) suggested that a total of 180 animals inhabited Finnmark in the early 1960s. Bjorge (1991) reported 195 harbor seals in Finnmark as an estimate for the years 1981-1984. In 1990 a minimum number of 221 harbor seals were counted during breeding in Finn-
160 MARINE MAMMAL SCIENCE, VOL. 13, NO. 1, 1997
mark (Table l), and in September and October, Henriksen and Haug (1994) counted 330 harbor seals in the county. The majority of the harbor seals in Finnmark are located in the fjords between Nordkapp and Kongsfjord (Hen- riksen 1995, Table 1, Fig. 1). Counts made after 1990 indicate that the num- ber of harbor seals is stable in this area (G. Henriksen, unpublished data). A possible increase in numbers of harbor seals in Finnmark during the last 30 yr (see Henriksen and Haug 1994) may reflect reduced hunting pressure and increased legal protection (Henriksen 1995).
Pleske (1887, cited in Kondakov 1992) is the first to write about the num- ber of harbor seals along the Murman coast, but Smirnov (1903, 1908) proved that these seals were ringed seals and not harbor seals. According to Knipow- itsch (1908), three harbor seals were caught on the Murman coast at the beginning of this century (6 April 1900 at Nokuyev, 4 May 1900 at Rynda, and in April 1901 at Kildin) (Fig. 1). During the following 90 yr, harbor seals have been considered a rarity along the Murman coast (Geptner et al. 1976; Kondakov 1992; Zirjanov, in press). A single harbor seal was observed on rocks during low tide in Oscar Bay, Dalnie Zelenty Inlet, in August 1985. In June 1986 a harbor seal was seen on the small islet in the inlet of the river Rynda, and in March 1989, a swimming harbor seal was observed near the island of Nokuyev (Fig. 1). In March 1990, 50 harbor seals were observed in Ivanoyskaya Bay near Nokuyev and, in June, breeding of the species was documented for the first time on the Murman coast (Table 1). Counts made after 1990 indicate that the number of harbor seals is increasing in this colony (Ziryanov, Moskvin and Kondakov, unpublished data). Questionnaires to local people confirmed that the harbor seal was a new species in the area. The first animals arrived during autumn 1989, when 20 individuals were counted (Kondakov 1992). Two of the more recent observations on the Murman coast (1986, 1989) are from the same area where at least two animals were caught at the beginning of the 20th century (Smirnov 1903, Knipowitsch 1908).
Harbor seals are considered rare in the eastern Barents Sea (Scheffer 1958). In 1840, K. E. Baer obtained a harbor seal skull from the western coast of Novaya Zemlya (Smirnov 1903>, and this must be the easternmost harbor seal on record. As far as we know, no seal surveys have been carried out in these areas during the last decades.
On Svalbard, harbor seals are found predominantly along the west coast of Spitsbergen, especially along the coast of Prins Karls Forland, the area with the least sea-ice (Vinje 1985, Gjertz and Borset 1992) (Fig. 1). Ice conditions in the archipelago vary between years, and local polynyas occur, making it possible for seals to inhabit other areas than the west coast of Spitsbergen. Harbor seals have been observed at southern Edge@ya, one animal in May/June 1965 (0. Loner, personal communication to I. Gjertz, 1992) and three animals in August 1990 (T. G. Smith, personal communication to I. Gjertz, 1990). These seals and the seal shot west of Sjupryene in 1898 (Rome, and Schau.dinn 1900) most likely moved into these areas when the ice receded.
Harbor seals are found associated with the pack ice in the western Barents Sea, at least for parts of the year. These are most likely animals from western
NOTES 161
Spitsbergen which have moved south in winter with the advancing ice, as seen in some animals tagged with satellite transmitters (Gjertz and Wiig, unpub- lished information). Harbor seals are not known to haul out or breed at Bjornoya, but it is possible that this may happen occasionally. In the 1970s (year and date unknown) a harbor seal mother and pup were killed on the ice east of Bjornoya (V. Potelov, personal communication to I. Gjertz, 1994).
Based on several breeding counts of harbor seals in the period 1975-1987, Presterud and Gjertz (1990) estimated the total population in Svalbard to number 500-600 animals, Kondakov (1992) reported that less than 70 in- dividuals were found in one colony on the Murman coast, and Henriksen and Haug (1994) counted 330 individuals during the moulting period in 1991 in Finnmark. This suggests a total population of 900--1,000 harbor seals in the Barents Sea. In the present study we have used only observed individuals for our estimates; 661 harbor seals (including 148 pups) were observed in the Barents Sea during the breeding period in June/July 1990 (Table 1). This seems to be in accordance with the estimation of the total population. Thomp- son et al. (1994) found that radio-tracked harbor seals did restrict their range considerably during the pupping period and also increased the amount of time they spent on land. However, an unknown proportion of seals is in the water during surveys, so survey counts represent only a minimum population esti- mate (see Terhune and Almon 1983).
The moult period is commonly regarded as the most appropriate time to count harbor seals (e.g., Thompson and Harwood 1990), but estimation of pup production cannot be made at the same time, as weaned pups cannot easily be distinguished from older animals. Future surveys should cover both the pupping and moulting peaks in the same year to improve the results from this study; hopefully, they will be thermal image surveys, which have proved to be successful in monitoring harbor seal colonies (see Duck et al. 1995).
ACNOWLEDGMENTS
Thanks to Tore Haug for valuable comments on the manuscript and to Rob Barrett for improvements of the English.
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ZIRJANOV, C. V. In press. Ivanovskaja Bay-the object of seashore reserve territory. Murman Marine Biological Institute, Russian Academy of Science. (In Russian).
GUNNAR HENRIKSEN, Rogaland Consultants as., P. 0. Box 1137, 4301 Sand- nes, Norway; IAN GJERTZ, Norwegian Polar Institute, P. 0. Box 5072 Major- stuen, N-0301 Oslo, Norway; ANDREJ KONDAKOV, Murman Marine Biological Institute, Russian Academy of Science, Vladimirskaya 17, 183023 Murmansk, Russia. Received 7 February 1996. Accepted 16 May 1996.
