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Status of the harbour seal phoca vitulina L. in Norway
Biological Conservation 58 (1991) 229-238
Status of the Harbour Seal Phoca vitulina L. in Norway
Arne Bjorge Norwegian Institute for Nature Research, University of Oslo, PO Box 1037 Blindern, 0315 Oslo 3, Norway
(Received 23 August 1990; revised version received 17 January 1991; accepted 21 January 1991)
ABSTRACT The current estimate of the number of harbour seal Phoca vitulina in Norwegian waters, including Svalbard, is 4129, based on actual counts of seals at the haul-out sites during the period 1977-88. Comparison with an estimate obtained during the early 1960s indicates that there has been little change in the overall number of harbour seals in Norway during the last 25 years. Three distinct types of habitats are utilized by harbour seals in Norway--open rock), coasts, deep fjords and estuarine sandbanks. The habitat types and the status of legislative protection of harbour seals and their habitats are described.
INTRODUCTION In the eastern North Atlantic the harbour or common seal Phoca vitulina L. is distributed from northern Portugal (rare) to the Barent Sea, around Iceland and in the south-western Baltic (Biggs, 1981). In Norway harbour seals have been hunted for fur and food since historical times. An archaeological excavation in Bolstadfjord, western Norway, shows that it was the second most important mammal in the diet of troglodyte stone-age man in that area (Olsen, 1976). Hunting coastal seals has, until recently, been an important source of income to a few families in northern Norway. In the first part of the 20th century harbour seals were regarded as vermin, with a bounty placed on them in some areas. As a result some local populations were much depleted. Needs for fat, meat and skin sustained the hunt in the 229 Biol. Conserv. 0006-3207/91/$03"50 © 1991 Elsevier Science Publishers Ltd, England. Printed in Great Britain
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years after the second world war, but the interest in h a r b o u r seal hunting decreased in the 1960s. Although hunting may have depleted local populations o f h a r b o u r seals in Norway, there are no hunting statistics or time series o f popul at i on estimates available that can be used to confirm this. T he first nationwide census o f h a r b o u r seals in N o r w a y was carried out in the early 1960s by Oynes, who estimated a total popul at i on size o f a b o u t 4000. According to Oynes (1964, 1966) the species had suffered a severe decline in this century, and was under severe threat in some areas. King (1983) wrote that there were perhaps 1000 h a r b o u r seals in Norway, but gave no reference for her data source. This was most pr oba bl y an underestimate o f the popul at i on size. This paper reviews available published and unpublished i nform at i on on TABLE 1
Occurrence of Harbour Seals in Norway--Comparison of Recent Surveys with Population Sizes Reported by I~ynes (1964, 1966) Count)'
Number o f harbour seals based on recent counts (1977-89) ° Open coast Fjord Sandbanks
Oslofjord and the Skagerrak coast Ostfold Vestfold Telemark Aust-Agder
43 10 20 20
Total
Harbour seals recorded by Oynes (1964, 1966)
43 10 20 20
100 30 40 20
North Sea coast Vest-Agder Rogaland Hordaland Sogn og Fjordane
48
74
122
305
65
370
50 250 <50 350
Norwegian Sea coast More og Romsdal Sor-Trondelag Nord-Trondelag Nordland Troms
954 340 195 916 444
954 340 195 916 444
1050 490 130 600 700
Barent Sea coast Finnmark
165
195
180
Svalbard
500
Total number of harbour seals
3 960
30
500 139
30
a Maximum number of seals recorded at each haul-out site. bExcluding Svalbard.
4 129
4 040b
Status of the harbour seal in Norway
231
the distribution and abundance of the harbour seal in Norway, describes the preferred haul-out and breeding habitats, and reports on the status of legislative protection of the seals and their habitats.
HABITATS There are three distinct types of habitats utilized by harbour seals in Norway--open rocky coast, deep fjords and estuarine sandbanks. More than 95% occur in shallow coastal waters, using intertidal rocks or small Barent S e a FINNMARK
TROMS
cs ....
j -t
/-,.f @
0
/
Norwegian S e a
NORDLAND / NORD-TReNDEL.AGt~,~
F.... •
/
M~RE OG ROMSDAL
("
,urlandsfjord
/
.......... ROGAL~N?.~'""
~, ",,e..S.TFOLO "
"'-.VESTFOLD ",. . .TELEMARK .... VEST-AGDER ! AUST-AGDER I
I
North Sea
~
Skagerrak
Fig. 1. Examples of three distinct types of harbour seal habitats: IS, coastal archipelago (Hvaler, Orskj~era and Froan); 0 , fjord (Lysefjord and Aurlandsfjord); A, sandbankestuarine (Tana estuary). The figure also shows the administrative counties and sea areas described in the text and in Table 1.
232
Arne Bjorge
islands (skerries) as haul-out sites located at a distance from the mainland or larger islands, for example Torbjornskj~er at Hvaler, Orskja~ra and Froan (Fig. 1). A few small colonies, constituting about 3% of the total population, are resident in deep fjords, where the seals may haul out on boulders or ledges located under steep and inaccessible cliffs or precipices. Lysefjord and Aurlandsfjord (Fig. l) are examples of this type of habitat, which is unique for harbour seals in Europe. In general, harbour seals favour intertidal sandbanks in estuaries and around sandy coasts (King, 1983), but in Norway there is only one colony resident in a sandbank area, in the Tana river estuary in Finnmark county (Fig. 1). The seals use the sandbanks for haul-out during the period of low tide, and for breeding and moulting. The Tana estuary is located in a fjord, but differs topographically from the fjord habitat type described above, due to its extensive shallow water area. It also differs from the two other habitat types with regard to the substrate on the haul-out sites. Table 1 shows the occurrence of seals at each habitat type.
DISTRIBUTION A N D A B U N D A N C E Methods Oynes (1964, 1966) based his estimates of population sizes mainly on information obtained by interviewing or receiving questionnaires from fishermen, seal hunters, lighthouse keepers and others supposed to possess knowledge about local seal populations. Several institutions have conducted local surveys of harbour seals, and there may be additional information that has escaped attention in thk-~ review. However, most of the recent information has come through surveys carried out by the Institute of Marine Research in Bergen during 1977-88. Some parts of the Norwegian coast have not been surveyed since the 1960s. The 1977-88 surveys were carried out by boat mainly during the breeding season (June-July), at or just after the peak of delivery, and pups were included in the number of seals recorded. Surveys made at other times of year are noted below. The seals were counted when gathered on haul-out sides at low tide. To diminish the risk of double recordings all neighbouring haul-out sites were, as far as possible, surveyed during the same period of low tide. Seals seen in the water off the haul-out sites were also counted and added to the nearest group of hauled-out seals but it is likely that some swimming seals will have been missed. Only figures for actual counts are given here, and they may therefore differ from reports where local
Status of the harbour seal in Norway
233
population sizes are estimated. In the absence of data to provide a correction factor the figures presented are, therefore, probably underestimates of actual populations.
Population sizes Table 1 summarizes the information on population sizes. The number of seals are given for each administrative county (see Fig. 1) to facilitate comparison with the information provided by IOynes (1964, 1966). Oslofjord and the Skagerrak coast from Ostfold county to Aust-Agder COblnty
The major seal colony in this area is located at Hvaler in IOstfold, close to the Swedish border. The number of seals was estimated at about 20 in the 1950s (Lone, 1958), about 100 in the 1960s (¢0ynes, 1966) and a total of 255 moulting seals was observed at Hvaler in August 1983 (Bjorge et al., 1983). This population suffered severely during the phocine distemper epidemic in 1988, and Markussen (1989) recorded 43 seals including seven pups in July 1989. Oynes cited Lono's (1958) report of 15-20 seals from inner Oslofjord, but Ugland et al. (1984) concluded that there are at present no colonies in this area. L~no (1958) further reported a colony of about 30 seals in Vestfold county, which was confirmed by tOynes (1966). However, this number seems to be too high for the present situation, and according to the local environmental authority there were about 10 seals in this area in 1987. tOynes (1966) estimated a population size of 35-40 seals in Telemark. P. E. Aspholm (pers. comm.) observed 20 animals (including four pups) in July 1988. In Aust-Agder county Oynes (1966) estimated the total population at less than 20 seals. This is in accordance with observations made in 1983 (Knutsen et al., 1984). North Sea coast from Vest-Agder county to Sogn og Fjordane county According to tOynes (1966) the total population in Vest-Agder did not exceed 50 seals, although several small groups were known to occur. No recent surveys have been carried out in this county. In Rogaland county I~ynes (1966) reported a total of about 250 seals. A total of 48 seals was recorded when the outer coast was surveyed in 1981 (Bj~rge et al., 1982), and 74 seals recorded in Lysefjord in August 1989 (Bjorge et al., 1989). According to Oynes (1966) there were less than 50 seals in Hordaland county. No survey has been carried out since then in Hordaland. Recently Wiig and Oritsland (1987) reported a total of about 370 seals in Sogn og Fjordane county, which is in accordance with Oynes' (1960) estimate of about 350 seals.
234
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Norwegian Sea coast from More og Romsdal county to Troms county Oynes (1964) reported 1050 seals in More og Romsdal, while 954 were observed during surveys in 1978-80 (Bj~rge, unpublished data). A total of 186 seals were observed in Froan nature reserve in August 1989 (Bj~rge et al., 1989), and 154 in other areas of S~r-Trondelag county in 1979 (Bjorge, unpublished data). The recent total of 340 seals is appreciably less than the 490 reported by 1Dynes (1964) for this county. A population of 130 harbour seals in Nord-Trondelag county was reported by IOynes (1964); the best recent estimate based on actual counts in 1977 (Benjaminsen et al., 1978) and 1979 (Bjorge, unpublished data) is 195. Oynes estimated the population in Nordland county to be about 600. Surveys conducted in 1977-80 (Bjorge, unpublished data) revealed a total of 100 seals in the southern part of the county. Northern Nordland was surveyed in July 1987 and June-July 1988 (Wiig, 1989a) and 816 seals were recorded, giving a total of 916 seals for the whole of Nordland county. Oynes (1964) gave a population size of about 700 harbour seals in Troms, but only 444 were recorded when this county was surveyed in 1987 (Bergflodt et al., 1987). Barents Sea coast--Finnmark county According to tOynes (1964) the harbour seals in Finnmark had suffered a severe decline in the first part of this century, and he reported a total of 180. Finnmark was surveyed by boat in 1981 (Bj~rge et al., 1982) and 1983 (Bjorge, unpublished data). The most important haul-out sites were also covered by an aerial survey in April 1984 (Bjorge, unpublished data). The highest harbour seal total recorded was 195. Svalbard The only group of harbour seals known at Svalbard inhabits the west shores of Prins Karls Forland (about 80 ° N). Based on a ground count in 1985, Wiig (1989b) reported a population of about 500 seals in that area.
STATUS OF LEGISLATIVE PROTECTION
Protection of the species Seals in Norway are in general managed by the Ministry of Fisheries pursuant to the Sealing Act of 1951 and the Marine Fisheries Act of 1983. Local protection of harbour seals was established at Tjotta in Nordland county in 1962, and at Orskj~era in More og Romsdal county in 1966. In 1973 local protection was superseded by a general protection of seals in
Status of the harbour seal in Norway
235
South Norway from Ostfold county to Sogn og Fjordane county inclusive. The same decree allows hunting in all areas north of Sogn og Fjordane. The hunting seasons starts on 1 December (recently changed to 1 November in some areas) and ends on 30 April. The hunt is not limited by quotas or number of hunters, and no catch statistics are recorded to show the extent of the hunt. In addition to the regular hunt, a culling programme was conducted by the fisheries authorities in the period 1981-86 from More og Romsdal to Nordland. According to Wiig (1987) a total of 1006 harbour seals was culled in this period. In 1990 a working group established by the Ministry of Fisheries presented a proposal for a new management regime for seals in Norwegian coastal waters (Anon., 1990). This recommended that all culling programmes should cease, and that seals should be given general legislative protection. Hunting will only be conducted if special permission is granted, and which will not be given unless it can be proven that the local seal population can sustain hunting. The numbers killed will also have to be reported.
Status of habitat protection The Sealing and the Marine Fisheries Acts do not provide a legislative basis for establishing protected areas. However, several protected areas are established along the Norwegian coast pursuant to the Nature Conservation Act, and are managed by the Ministry of Environment. Most are sea-bird reserves, but the regulations (including limitations on human access to the protected areas) give due protection to harbour seals. In other protected areas, such as Froan nature reserve, the main objective is to protect seal habitats, and at Froan landing is prohibited during the harbour seal birth and lactation period. All harbour seal haul-out sites at Svalbard are protected. About 20% of the harbour seals in Norway are thus breeding in protected areas (Bjorge, 1987). No fjord or sandbank habitat is as yet protected for seals. However, a proposal to protect the Tana estuary as a nature reserve is presently being considered.
DISCUSSION The Oslofjord and the Skagerrak coasts are adjacent to large human settlements and urban areas, and form a major recreation area during the summer season. H u m a n disturbance during the birth and lactation period
236
Arne Bj~rge
for harbour seals might have an impact on the ability of the seal population to increase, although the counts of 305 seals in the Oslofjord-Skagerrak area prior to the phocine distemper epidemic indicate an increase compared with the estimated population size of 200 seals in the 1960s. However, no recovery was recorded outside the Hvaler area although the neighbouring populations on the Swedish side of the border did increase exponentially, with an annual rate of 0.12 prior to the epidemic (Heide-J~rgensen & HfirkSnen, 1988). A total of 950 harbour seals was recorded dead along the Norwegian coast south of about 63 ° N after the epidemic in 1988 (Krogsrud et al., 1990), most in the Oslofjord-Skagerrak area, and it remains unclear whether these originated from Norwegian populations or from the larger Swedish or Danish populations. Studies are in progress to evaluate the effects of the disease, and preliminary results indicate a 75% reduction of the population at Hvaler (Markussen, 1989). Based on the population size of about 700 seals given by Oynes (1966) and the recent counts of 490, there has been a decrease in number of harbour seals recorded along the Norwegian North Sea coast. However, the recent surveys have an incomplete coverage, and there is little information on the impact of the seal disease along this coastline. Few overall changes in harbour seal population sizes are recorded along the Norwegian Sea and the Barent Sea coasts. A total of 916 in Nordland is apparently an increase compared with the information given by Dynes (1964), while a decrease is recorded in Troms. Based on the current estimate of the total population size, the recent cull of a total of 1006 harbour seals in this area in the period 1981-86 (Wiig, 1987) was clearly higher than the sustainable harvest of the population. Although local variations have been observed, this review indicates that there has apparently been little change during the last 25 years in the overall number of harbour seals in Norway. However, recent culling and the phocine distemper epidemic may disturb this picture. In conclusion, it is difficult with the present information and assessment methods to detect changes in population size, and it is not possible to evaluate the effects of the management regime introduced in 1973, nor the effects of protected areas. There is a demand for better assessment methods, and if in the future these are based on ceunts at haul-out sites there is a need for a method to convert the observations to population size or an index of abundance. Despite the extensive coastline, the population of harbour seals in Norway is small compared to populations in other North Sea countries and Iceland. This may reflect a low natural carrying capacity, or high mortalities caused by incidental catches in our extensive coastal fisheries as well as our long and prevailing tradition of seal hunting. However, if the proposed new
Status of the harbour seal in Norway
237
m a n a g e m e n t regime becomes implemented it will surely improve the legislative status of the h a r b o u r seal in Norway. This improvement will in principle m a k e its m a n a g e m e n t similar to that adopted for large terrestrial m a m m a l s in N o r w a y and for h a r b o u r seals in our neighbouring countries.
ACKNOWLEDGEMENTS This review is based on information m a d e available by several persons and institutions, and I t h a n k all for their contributions. Most of the information was, however, collected as a part of the Coastal Seal Project at the Institute of Marine Research in Bergen, and I am particularly obliged to this institute for letting me use unpublished data. I also thank Phil H a m m o n d for useful c o m m e n t s on the manuscript, and I particularly appreciate his translation of my 'English' into a more readable form.
REFERENCES Anon. (1990). Landsplan for forvaltning av kystsel. Norges Offentlige Utredninger. Fiskeridepartementet. No. 12. Benjaminsen, T., Bergfladt, B., Oritsland, T., Bj~rge, A., Bronndal, M., Paasche, A., Sivertsen, K., Brodie, P. & Toklum, K. (1978). Undersokelser av steinkobbe og havert p~ norskekysten fra Nordmore til Sorhelgeland i 1977. Rapp. nr 1, Fiskeridirektoratet 1978, 1-4. Bigg, M. A. (1981). Harbour seal Phoca vitulina Linnaeus 1758 and Phoca largha Pallas 1811. In Handbook of Marine Mammals. Vol. 2, Seals, ed. S. H. Ridgway & J. H. Harrison. Academic Press, London, pp. 1-27. Bjorge, A. (1987). Status of marine mammal habitat protection in Norway. Proc. Coastal Seal Syrup., Oslo, 28-29 April 1987, 244-53. Bjorge, A., Bergflodt, B., Fagerheim, K. A., Oritsland, T. & Skadsheim, A. (1982). Undersakelser av steinkobbe og havert i Rogaland og Finnmark i 1981. Fisken Hay., 1983(2), 1-9. Bjarge, A., Fagerheim, K. A. & Morkved, B. (1983). Telling av steinkobbe ved Hvaler i 1983. Fisken Hay., 1983(3), 1-4. Bjorge, A., Thompson, D. & Hammond, P. (1989). Foraging behaviour of coastal marine mammals. Report 1: Planning survey 14-25 August 1989 (Mimeograph). Heide-Jorgensen, M.-P. & H/irk6nen, T. J. (1988). Rebuilding seal stocks in the Kattegat-Skagerrak. Mar. Mammal Sci., 4, 231-46. King, J. E. (1983). Seals of the World, 2nd edn. Oxford University Press, Oxford. Knutsen, L. O., Stenmark, G. & Ugland, K. I. (1984). Undersokelser av steinkobbe i ytre Oslofjord og langs Skagerrakkysten. Report, University of Oslo (Mimeograph). Korgsrud, J., Evensen, O., Holt, G., Hole, S. & Markussen, N.H. (1990). Seal distemper in Norway in 1988 and 1989. Vet. Rec., 126, 460-1.
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Lono, O. (1958). Telling av steinkobbe i Oslofjorden og langs Sorlandskysten. Fauna, 11(4), 145-6. Markussen, N. H. (1989). Effects of the epizootic on a harbour seal (Phoca vitulina) population in Norway. Abstract, Biennial Conference on the Biology of Marine Mammals, 8th, Pacific Grove, 7-11 December 1989. Ugland, K. I., Stenmark, G., Anstensrud, M. & Knutsen, L. O. (1984). Steinkobbe i Oslofjorden. Fauna, 37, 1-5. Olsen, H. (1976). Skipshellaren. Osteologisk materiale. Report, Zoologisk Museum, University of Bergen (Mimeograph). Oynes, P. (1964). Sel pgt norskekysten fra Finnmark til More. Fiskets Gang, 48, 694-707. Oynes, P. (1966). Sel i Sor-Norge. Fiskets Gang, 45, 834-9. Wiig, O. (1987). A review of coastal seal culls in Norway 1980 to 1986. Proc. Coastal Seal Symp., Oslo, 28-29 April 1987, 227-34. Wiig, O. (1989a). The grey seal Halicoerus grypus (Fabricius) and the common seal Phoca vitulina L. in Lofoten and Vester~ien, northern Norway. Fauna norv., Ser. A, 10, 1-4. Wiig, O. (1989b). A description of common seals, Phoca vitulina L. 1758, from Svalbard. Mar. Mammal Sci., 5, 149-58. Wiig, O. & Oien, N. (1988). Recoveries of common seals Phoca vitulina L. tagged along the Norwegian coast. Fauna norv., Ser. A, 9, 51-2. Wiig, O. & Oritsland, T. (1987). The grey seal Halichoerusgrypus (Fabricius) and the common seal Phoca vitulina L. in Sogn og Fjordane, western Norway. Fauna norv., Ser. A, 8, 21-4.
Status of the Harbour Seal Phoca vitulina L. in Norway
Arne Bjorge Norwegian Institute for Nature Research, University of Oslo, PO Box 1037 Blindern, 0315 Oslo 3, Norway
(Received 23 August 1990; revised version received 17 January 1991; accepted 21 January 1991)
ABSTRACT The current estimate of the number of harbour seal Phoca vitulina in Norwegian waters, including Svalbard, is 4129, based on actual counts of seals at the haul-out sites during the period 1977-88. Comparison with an estimate obtained during the early 1960s indicates that there has been little change in the overall number of harbour seals in Norway during the last 25 years. Three distinct types of habitats are utilized by harbour seals in Norway--open rock), coasts, deep fjords and estuarine sandbanks. The habitat types and the status of legislative protection of harbour seals and their habitats are described.
INTRODUCTION In the eastern North Atlantic the harbour or common seal Phoca vitulina L. is distributed from northern Portugal (rare) to the Barent Sea, around Iceland and in the south-western Baltic (Biggs, 1981). In Norway harbour seals have been hunted for fur and food since historical times. An archaeological excavation in Bolstadfjord, western Norway, shows that it was the second most important mammal in the diet of troglodyte stone-age man in that area (Olsen, 1976). Hunting coastal seals has, until recently, been an important source of income to a few families in northern Norway. In the first part of the 20th century harbour seals were regarded as vermin, with a bounty placed on them in some areas. As a result some local populations were much depleted. Needs for fat, meat and skin sustained the hunt in the 229 Biol. Conserv. 0006-3207/91/$03"50 © 1991 Elsevier Science Publishers Ltd, England. Printed in Great Britain
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years after the second world war, but the interest in h a r b o u r seal hunting decreased in the 1960s. Although hunting may have depleted local populations o f h a r b o u r seals in Norway, there are no hunting statistics or time series o f popul at i on estimates available that can be used to confirm this. T he first nationwide census o f h a r b o u r seals in N o r w a y was carried out in the early 1960s by Oynes, who estimated a total popul at i on size o f a b o u t 4000. According to Oynes (1964, 1966) the species had suffered a severe decline in this century, and was under severe threat in some areas. King (1983) wrote that there were perhaps 1000 h a r b o u r seals in Norway, but gave no reference for her data source. This was most pr oba bl y an underestimate o f the popul at i on size. This paper reviews available published and unpublished i nform at i on on TABLE 1
Occurrence of Harbour Seals in Norway--Comparison of Recent Surveys with Population Sizes Reported by I~ynes (1964, 1966) Count)'
Number o f harbour seals based on recent counts (1977-89) ° Open coast Fjord Sandbanks
Oslofjord and the Skagerrak coast Ostfold Vestfold Telemark Aust-Agder
43 10 20 20
Total
Harbour seals recorded by Oynes (1964, 1966)
43 10 20 20
100 30 40 20
North Sea coast Vest-Agder Rogaland Hordaland Sogn og Fjordane
48
74
122
305
65
370
50 250 <50 350
Norwegian Sea coast More og Romsdal Sor-Trondelag Nord-Trondelag Nordland Troms
954 340 195 916 444
954 340 195 916 444
1050 490 130 600 700
Barent Sea coast Finnmark
165
195
180
Svalbard
500
Total number of harbour seals
3 960
30
500 139
30
a Maximum number of seals recorded at each haul-out site. bExcluding Svalbard.
4 129
4 040b
Status of the harbour seal in Norway
231
the distribution and abundance of the harbour seal in Norway, describes the preferred haul-out and breeding habitats, and reports on the status of legislative protection of the seals and their habitats.
HABITATS There are three distinct types of habitats utilized by harbour seals in Norway--open rocky coast, deep fjords and estuarine sandbanks. More than 95% occur in shallow coastal waters, using intertidal rocks or small Barent S e a FINNMARK
TROMS
cs ....
j -t
/-,.f @
0
/
Norwegian S e a
NORDLAND / NORD-TReNDEL.AGt~,~
F.... •
/
M~RE OG ROMSDAL
("
,urlandsfjord
/
.......... ROGAL~N?.~'""
~, ",,e..S.TFOLO "
"'-.VESTFOLD ",. . .TELEMARK .... VEST-AGDER ! AUST-AGDER I
I
North Sea
~
Skagerrak
Fig. 1. Examples of three distinct types of harbour seal habitats: IS, coastal archipelago (Hvaler, Orskj~era and Froan); 0 , fjord (Lysefjord and Aurlandsfjord); A, sandbankestuarine (Tana estuary). The figure also shows the administrative counties and sea areas described in the text and in Table 1.
232
Arne Bjorge
islands (skerries) as haul-out sites located at a distance from the mainland or larger islands, for example Torbjornskj~er at Hvaler, Orskja~ra and Froan (Fig. 1). A few small colonies, constituting about 3% of the total population, are resident in deep fjords, where the seals may haul out on boulders or ledges located under steep and inaccessible cliffs or precipices. Lysefjord and Aurlandsfjord (Fig. l) are examples of this type of habitat, which is unique for harbour seals in Europe. In general, harbour seals favour intertidal sandbanks in estuaries and around sandy coasts (King, 1983), but in Norway there is only one colony resident in a sandbank area, in the Tana river estuary in Finnmark county (Fig. 1). The seals use the sandbanks for haul-out during the period of low tide, and for breeding and moulting. The Tana estuary is located in a fjord, but differs topographically from the fjord habitat type described above, due to its extensive shallow water area. It also differs from the two other habitat types with regard to the substrate on the haul-out sites. Table 1 shows the occurrence of seals at each habitat type.
DISTRIBUTION A N D A B U N D A N C E Methods Oynes (1964, 1966) based his estimates of population sizes mainly on information obtained by interviewing or receiving questionnaires from fishermen, seal hunters, lighthouse keepers and others supposed to possess knowledge about local seal populations. Several institutions have conducted local surveys of harbour seals, and there may be additional information that has escaped attention in thk-~ review. However, most of the recent information has come through surveys carried out by the Institute of Marine Research in Bergen during 1977-88. Some parts of the Norwegian coast have not been surveyed since the 1960s. The 1977-88 surveys were carried out by boat mainly during the breeding season (June-July), at or just after the peak of delivery, and pups were included in the number of seals recorded. Surveys made at other times of year are noted below. The seals were counted when gathered on haul-out sides at low tide. To diminish the risk of double recordings all neighbouring haul-out sites were, as far as possible, surveyed during the same period of low tide. Seals seen in the water off the haul-out sites were also counted and added to the nearest group of hauled-out seals but it is likely that some swimming seals will have been missed. Only figures for actual counts are given here, and they may therefore differ from reports where local
Status of the harbour seal in Norway
233
population sizes are estimated. In the absence of data to provide a correction factor the figures presented are, therefore, probably underestimates of actual populations.
Population sizes Table 1 summarizes the information on population sizes. The number of seals are given for each administrative county (see Fig. 1) to facilitate comparison with the information provided by IOynes (1964, 1966). Oslofjord and the Skagerrak coast from Ostfold county to Aust-Agder COblnty
The major seal colony in this area is located at Hvaler in IOstfold, close to the Swedish border. The number of seals was estimated at about 20 in the 1950s (Lone, 1958), about 100 in the 1960s (¢0ynes, 1966) and a total of 255 moulting seals was observed at Hvaler in August 1983 (Bjorge et al., 1983). This population suffered severely during the phocine distemper epidemic in 1988, and Markussen (1989) recorded 43 seals including seven pups in July 1989. Oynes cited Lono's (1958) report of 15-20 seals from inner Oslofjord, but Ugland et al. (1984) concluded that there are at present no colonies in this area. L~no (1958) further reported a colony of about 30 seals in Vestfold county, which was confirmed by tOynes (1966). However, this number seems to be too high for the present situation, and according to the local environmental authority there were about 10 seals in this area in 1987. tOynes (1966) estimated a population size of 35-40 seals in Telemark. P. E. Aspholm (pers. comm.) observed 20 animals (including four pups) in July 1988. In Aust-Agder county Oynes (1966) estimated the total population at less than 20 seals. This is in accordance with observations made in 1983 (Knutsen et al., 1984). North Sea coast from Vest-Agder county to Sogn og Fjordane county According to tOynes (1966) the total population in Vest-Agder did not exceed 50 seals, although several small groups were known to occur. No recent surveys have been carried out in this county. In Rogaland county I~ynes (1966) reported a total of about 250 seals. A total of 48 seals was recorded when the outer coast was surveyed in 1981 (Bj~rge et al., 1982), and 74 seals recorded in Lysefjord in August 1989 (Bjorge et al., 1989). According to Oynes (1966) there were less than 50 seals in Hordaland county. No survey has been carried out since then in Hordaland. Recently Wiig and Oritsland (1987) reported a total of about 370 seals in Sogn og Fjordane county, which is in accordance with Oynes' (1960) estimate of about 350 seals.
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Norwegian Sea coast from More og Romsdal county to Troms county Oynes (1964) reported 1050 seals in More og Romsdal, while 954 were observed during surveys in 1978-80 (Bj~rge, unpublished data). A total of 186 seals were observed in Froan nature reserve in August 1989 (Bj~rge et al., 1989), and 154 in other areas of S~r-Trondelag county in 1979 (Bjorge, unpublished data). The recent total of 340 seals is appreciably less than the 490 reported by 1Dynes (1964) for this county. A population of 130 harbour seals in Nord-Trondelag county was reported by IOynes (1964); the best recent estimate based on actual counts in 1977 (Benjaminsen et al., 1978) and 1979 (Bjorge, unpublished data) is 195. Oynes estimated the population in Nordland county to be about 600. Surveys conducted in 1977-80 (Bjorge, unpublished data) revealed a total of 100 seals in the southern part of the county. Northern Nordland was surveyed in July 1987 and June-July 1988 (Wiig, 1989a) and 816 seals were recorded, giving a total of 916 seals for the whole of Nordland county. Oynes (1964) gave a population size of about 700 harbour seals in Troms, but only 444 were recorded when this county was surveyed in 1987 (Bergflodt et al., 1987). Barents Sea coast--Finnmark county According to tOynes (1964) the harbour seals in Finnmark had suffered a severe decline in the first part of this century, and he reported a total of 180. Finnmark was surveyed by boat in 1981 (Bj~rge et al., 1982) and 1983 (Bjorge, unpublished data). The most important haul-out sites were also covered by an aerial survey in April 1984 (Bjorge, unpublished data). The highest harbour seal total recorded was 195. Svalbard The only group of harbour seals known at Svalbard inhabits the west shores of Prins Karls Forland (about 80 ° N). Based on a ground count in 1985, Wiig (1989b) reported a population of about 500 seals in that area.
STATUS OF LEGISLATIVE PROTECTION
Protection of the species Seals in Norway are in general managed by the Ministry of Fisheries pursuant to the Sealing Act of 1951 and the Marine Fisheries Act of 1983. Local protection of harbour seals was established at Tjotta in Nordland county in 1962, and at Orskj~era in More og Romsdal county in 1966. In 1973 local protection was superseded by a general protection of seals in
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235
South Norway from Ostfold county to Sogn og Fjordane county inclusive. The same decree allows hunting in all areas north of Sogn og Fjordane. The hunting seasons starts on 1 December (recently changed to 1 November in some areas) and ends on 30 April. The hunt is not limited by quotas or number of hunters, and no catch statistics are recorded to show the extent of the hunt. In addition to the regular hunt, a culling programme was conducted by the fisheries authorities in the period 1981-86 from More og Romsdal to Nordland. According to Wiig (1987) a total of 1006 harbour seals was culled in this period. In 1990 a working group established by the Ministry of Fisheries presented a proposal for a new management regime for seals in Norwegian coastal waters (Anon., 1990). This recommended that all culling programmes should cease, and that seals should be given general legislative protection. Hunting will only be conducted if special permission is granted, and which will not be given unless it can be proven that the local seal population can sustain hunting. The numbers killed will also have to be reported.
Status of habitat protection The Sealing and the Marine Fisheries Acts do not provide a legislative basis for establishing protected areas. However, several protected areas are established along the Norwegian coast pursuant to the Nature Conservation Act, and are managed by the Ministry of Environment. Most are sea-bird reserves, but the regulations (including limitations on human access to the protected areas) give due protection to harbour seals. In other protected areas, such as Froan nature reserve, the main objective is to protect seal habitats, and at Froan landing is prohibited during the harbour seal birth and lactation period. All harbour seal haul-out sites at Svalbard are protected. About 20% of the harbour seals in Norway are thus breeding in protected areas (Bjorge, 1987). No fjord or sandbank habitat is as yet protected for seals. However, a proposal to protect the Tana estuary as a nature reserve is presently being considered.
DISCUSSION The Oslofjord and the Skagerrak coasts are adjacent to large human settlements and urban areas, and form a major recreation area during the summer season. H u m a n disturbance during the birth and lactation period
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for harbour seals might have an impact on the ability of the seal population to increase, although the counts of 305 seals in the Oslofjord-Skagerrak area prior to the phocine distemper epidemic indicate an increase compared with the estimated population size of 200 seals in the 1960s. However, no recovery was recorded outside the Hvaler area although the neighbouring populations on the Swedish side of the border did increase exponentially, with an annual rate of 0.12 prior to the epidemic (Heide-J~rgensen & HfirkSnen, 1988). A total of 950 harbour seals was recorded dead along the Norwegian coast south of about 63 ° N after the epidemic in 1988 (Krogsrud et al., 1990), most in the Oslofjord-Skagerrak area, and it remains unclear whether these originated from Norwegian populations or from the larger Swedish or Danish populations. Studies are in progress to evaluate the effects of the disease, and preliminary results indicate a 75% reduction of the population at Hvaler (Markussen, 1989). Based on the population size of about 700 seals given by Oynes (1966) and the recent counts of 490, there has been a decrease in number of harbour seals recorded along the Norwegian North Sea coast. However, the recent surveys have an incomplete coverage, and there is little information on the impact of the seal disease along this coastline. Few overall changes in harbour seal population sizes are recorded along the Norwegian Sea and the Barent Sea coasts. A total of 916 in Nordland is apparently an increase compared with the information given by Dynes (1964), while a decrease is recorded in Troms. Based on the current estimate of the total population size, the recent cull of a total of 1006 harbour seals in this area in the period 1981-86 (Wiig, 1987) was clearly higher than the sustainable harvest of the population. Although local variations have been observed, this review indicates that there has apparently been little change during the last 25 years in the overall number of harbour seals in Norway. However, recent culling and the phocine distemper epidemic may disturb this picture. In conclusion, it is difficult with the present information and assessment methods to detect changes in population size, and it is not possible to evaluate the effects of the management regime introduced in 1973, nor the effects of protected areas. There is a demand for better assessment methods, and if in the future these are based on ceunts at haul-out sites there is a need for a method to convert the observations to population size or an index of abundance. Despite the extensive coastline, the population of harbour seals in Norway is small compared to populations in other North Sea countries and Iceland. This may reflect a low natural carrying capacity, or high mortalities caused by incidental catches in our extensive coastal fisheries as well as our long and prevailing tradition of seal hunting. However, if the proposed new
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237
m a n a g e m e n t regime becomes implemented it will surely improve the legislative status of the h a r b o u r seal in Norway. This improvement will in principle m a k e its m a n a g e m e n t similar to that adopted for large terrestrial m a m m a l s in N o r w a y and for h a r b o u r seals in our neighbouring countries.
ACKNOWLEDGEMENTS This review is based on information m a d e available by several persons and institutions, and I t h a n k all for their contributions. Most of the information was, however, collected as a part of the Coastal Seal Project at the Institute of Marine Research in Bergen, and I am particularly obliged to this institute for letting me use unpublished data. I also thank Phil H a m m o n d for useful c o m m e n t s on the manuscript, and I particularly appreciate his translation of my 'English' into a more readable form.
REFERENCES Anon. (1990). Landsplan for forvaltning av kystsel. Norges Offentlige Utredninger. Fiskeridepartementet. No. 12. Benjaminsen, T., Bergfladt, B., Oritsland, T., Bj~rge, A., Bronndal, M., Paasche, A., Sivertsen, K., Brodie, P. & Toklum, K. (1978). Undersokelser av steinkobbe og havert p~ norskekysten fra Nordmore til Sorhelgeland i 1977. Rapp. nr 1, Fiskeridirektoratet 1978, 1-4. Bigg, M. A. (1981). Harbour seal Phoca vitulina Linnaeus 1758 and Phoca largha Pallas 1811. In Handbook of Marine Mammals. Vol. 2, Seals, ed. S. H. Ridgway & J. H. Harrison. Academic Press, London, pp. 1-27. Bjorge, A. (1987). Status of marine mammal habitat protection in Norway. Proc. Coastal Seal Syrup., Oslo, 28-29 April 1987, 244-53. Bjorge, A., Bergflodt, B., Fagerheim, K. A., Oritsland, T. & Skadsheim, A. (1982). Undersakelser av steinkobbe og havert i Rogaland og Finnmark i 1981. Fisken Hay., 1983(2), 1-9. Bjarge, A., Fagerheim, K. A. & Morkved, B. (1983). Telling av steinkobbe ved Hvaler i 1983. Fisken Hay., 1983(3), 1-4. Bjorge, A., Thompson, D. & Hammond, P. (1989). Foraging behaviour of coastal marine mammals. Report 1: Planning survey 14-25 August 1989 (Mimeograph). Heide-Jorgensen, M.-P. & H/irk6nen, T. J. (1988). Rebuilding seal stocks in the Kattegat-Skagerrak. Mar. Mammal Sci., 4, 231-46. King, J. E. (1983). Seals of the World, 2nd edn. Oxford University Press, Oxford. Knutsen, L. O., Stenmark, G. & Ugland, K. I. (1984). Undersokelser av steinkobbe i ytre Oslofjord og langs Skagerrakkysten. Report, University of Oslo (Mimeograph). Korgsrud, J., Evensen, O., Holt, G., Hole, S. & Markussen, N.H. (1990). Seal distemper in Norway in 1988 and 1989. Vet. Rec., 126, 460-1.
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Lono, O. (1958). Telling av steinkobbe i Oslofjorden og langs Sorlandskysten. Fauna, 11(4), 145-6. Markussen, N. H. (1989). Effects of the epizootic on a harbour seal (Phoca vitulina) population in Norway. Abstract, Biennial Conference on the Biology of Marine Mammals, 8th, Pacific Grove, 7-11 December 1989. Ugland, K. I., Stenmark, G., Anstensrud, M. & Knutsen, L. O. (1984). Steinkobbe i Oslofjorden. Fauna, 37, 1-5. Olsen, H. (1976). Skipshellaren. Osteologisk materiale. Report, Zoologisk Museum, University of Bergen (Mimeograph). Oynes, P. (1964). Sel pgt norskekysten fra Finnmark til More. Fiskets Gang, 48, 694-707. Oynes, P. (1966). Sel i Sor-Norge. Fiskets Gang, 45, 834-9. Wiig, O. (1987). A review of coastal seal culls in Norway 1980 to 1986. Proc. Coastal Seal Symp., Oslo, 28-29 April 1987, 227-34. Wiig, O. (1989a). The grey seal Halicoerus grypus (Fabricius) and the common seal Phoca vitulina L. in Lofoten and Vester~ien, northern Norway. Fauna norv., Ser. A, 10, 1-4. Wiig, O. (1989b). A description of common seals, Phoca vitulina L. 1758, from Svalbard. Mar. Mammal Sci., 5, 149-58. Wiig, O. & Oien, N. (1988). Recoveries of common seals Phoca vitulina L. tagged along the Norwegian coast. Fauna norv., Ser. A, 9, 51-2. Wiig, O. & Oritsland, T. (1987). The grey seal Halichoerusgrypus (Fabricius) and the common seal Phoca vitulina L. in Sogn og Fjordane, western Norway. Fauna norv., Ser. A, 8, 21-4.