FiskDir. Skl-. Ser. HarCilders.. 18: 303-309.
T H E GREY SEAL, HALICHOERUS GRYPUS (FABRICIUS), I N ROGALAND, NORWAY
~ Y S T E I S \'GIG
Institute of Marine Research, Bergen, Norway
ABSTRACT
\2'1rc. 0. 1987. T h e grey seal, Halichoerus g ~ i ~ p u s (Fabricius). in Rogaland. Norway. FiskDir. .Ski-.
St?-. Hat Lkders.. 1 8: 303-309.
Surveys of grey seals in Rogaland, southwestern Norway, are reviewed. The highest numbers of adult seals have been observed in the spring, while far less are generally observed during the breeding season in the autumn. Pupping has been recorded, but it is rare in relation to the number of seals observed in the spring. T h e nearest breeding site of grey seals in Norway is at Froan, about 680 km to the north. T h e southernmost recovery of pups tagged at Froan is about 300 km north of the pupping sites in Rogaland. There are many recoveries in western Norway of grey seal pups tagged in Great Britain. There is, however, no information suggesting that British seals are being recruited to Norwegian breeding stocks or are establishing new breeding colonies on the Korwegian coast. It is reasonable to assume that most of the grey seals found in Rogaland in the spring are British and return to Britain in the breeding season. It is not known whether the recorded breedings in Rogaland are stragglers from British colonies or relate to a local stock.
I S T R O D U C T I O N
T h e grey seal, Halichoerus grypus, and the common seal, Phoca vitulina L., are the only resident seals on the Norwegian coast. e)l-\-Es (1964, 1966) surveyed the breeding colonies of both these species along the Norwegian coast and S u n r h r ~ ~ s , BOXXER, and van HAAFTEX (1978) estimated the total population of grey seals in Norway to be 2 000-3 000 seals.
A study of coastal seals and their interactions with inshore fisheries along the Norwegian coast from Stad (about 62"N)to Lofoten (about 68ON) was initiated by the Institute of Marine Research in 1974. T h e study was later extended to cover the larger part of the Norwegian coast. One result of this study is new information on the distribution and abundance of grey seals in Norway, summarized by M'IIG (1986), who has also given a more detailed
account for Fininnark county (\Z'II(; 1987). ?'he s ~ ~ r \ . c y s indicate a i~lininlurn stuck of 3100 g r q r scals in Nor\\-a)-.
O~.zl:s (1966) was unablc to \,crify an). brccclii~g of grc)- seals in southern Norway. T h e only reported I~rceding localit). was at E;jclr in Rogalancl, \vhcrc a couple of pups llacl I~cen reportcd in solllc years.
Rcccilt surIreys indicate that mol-c than 100 grc!- seals are found in Rogalaild during parts of tllr year) and breeding has no\\- hccn verified. There is, ho\vc\~er, a disparity b c t ~ ~ c c n the ohser~~ccl numbers of seals and the very few rccorclecl hirtlls. This disparity may he rclatecl to a n immigration of grcy scals fi-01x1 Britain, ~ ~ h i c h was recently rci7iewed 11)~ B,JMK(;I: and blc:c:oss~:~.~.
( 1986).
, 1 hc present paper gives a clctailcd account of recorded obscr\.ations of grey scals i l l Rogaland, south~vcstcrn Norlvay, \\,it11 a discussion of the status of the stock.
METHODS
T h c numhcrs of scals havc l,een cstinlatrcl from aerial and ground surveys carried out by the Sea M a m m a l Section of the Instititute of Marine Research.
T h e aerial surveys were made from t w i n - e ~ ~ g i n e d fixed-wing aircraft. I n additioil to direct counts, seals were photographed by 35-min hancl-held reflex-cameras, using colour rcvcrsal fihn as recon~me~iclccl by V.AUGH.\X (1 97 1). T h e ground sur17eys wrre made from 12'-15' Zodiac inflatable boats, which are well suited for rapid l a n c l i ~ ~ g s on rocky shores and skerries, enahling the seals to be visually counted. I n addition, observations have been reported by local fishermen.
I n 1984 a culliilg program for seals in Rogaland permitted the killing of 25 grey seals. I n fact, 15 were killed and the lower jaw, internal genitalia and stomach of cach of 1 1 scals were scnt to the Institute of Marine Research tbr further analysis. T h e animals were aged from tooth sections of thc canine of the lower jaw, and their reproductive status were classified from the internal genitalia.
Three foetuses collcctccl at K j ~ r in 1984 were weighed and thcir standard length (nose-tail) measurccl. Parturition dates \\,ere estinlated fi-om the rclati- onsllip in Boycl ( 1984).
RESULTS
Seal observations in Rogaland are recorded in Table 1, and the localities are shown in Fig. 1. Surveys have been performccl i11 February, March, h.lay, June, October, Sovenlbcr a n d December. Most of the grey seals were observed from February to June, and thc largest aggregation was found a t K j ~ r . Few adults a n d no pups lla\.c bccn obser\.ecl dui-i11g the s u r ~ ~ e y s in the
:305
Table I . Results of grey seal surveys in Rogalancl by the Institute of Marine Research.
Date
Numbcr of sales observed
Methotl Largest 'Total
azgregation 20 February 1984 Aircraft
1 March 1983 Boat 12 March 1984 Aircraft 30-3 1 May 198 1 Boat 1-3 June 198 1 Boat I I October 1982 Aircraft
7 Noveiiiber 198 1 Aircraft 29 Novembcr 1982 Aircraft 10 December 1985 Aircraft a) B,J@RCE et nl. 1982
h) BERGI-I.@JIY~ et 21. 1985
16 at K j ~ r 30 60 at Kjtlr 60
80 at K.j@r 90
36 at Utsira 36a)
60 at KjOr 752)
0 0 0
10 at KjGr lob)
breeding periocl from October to November. During the latest aerial survey (December 1983), only about 10 aclult grey seals were ohserveel at Icjnr. I11 additio11 to these observations, sui-vcys at Iijnr wcre perlbr~llccl on se\,cral occasions by boat, d ~ ~ r i n g a u t u m n 1985 (Table 2). O i ~ l y a Sew adults and no pups wcre obscrvecl.
hlost of the agcxcl grc). seals appeared to be !-oung. ancl only t\vo of' clc\.cn spccimcils Jverc olcici- than six years (Table 3 ) . 'The). \vcrc all shot in the a u t u m n , but only t ~ v o of' the sc\-cn lllalcs lyrre classified as mature. Aili li,ur fe'emalcs, ho\vc\.ei-. \ v e x pl~cgilant or llacl given birth during tile year of killing.
\\'eight ailcl stailclard Ien,ytll of tile Soet~~scs ancl tllc estimatccl partui-itioil dates arc givrn ill T a b l e 4.
I11 recent years, five white pups have been ohscr\.ccl at Kjnr (R. Roth pcrs.
comm. to B. Bergfl~clt), in ~ o \ ~ c i n b c r / D c c e r n b c r 1983 one white p u p was photographed a t Higgilen near I<vitsny ( L . Reillel-tscn pcrs. comm.), one
~ v h i t c p u p was seen a t Lausiilgen near Utsira on 22 .August 1984. ( 0 . T ~ r s t a d pers, c o r n i ~ ~ . to T. Oritsland); one ~vliite pup lvas obser\.ccl at K.jer oil 13 No\,ember 1984 (T. Olbcrg pers. c o m i ~ l . ) ; and a large pup, \vith re111nailts oS white hairs, was seen a t Higgilen near oil IC\rits0y 2 January 1985 ( L . Reiilertsell pers. comm.).
C i c\ seal7 ll\ cd 111 Koqalai~cl scr el a1 thousand rnls aqo ( \ \ I I L 1986)
.\I chacoloqlral c\ca\ ations nt cc\71strl151c~)), a btonne .\gc sltc ncai Sta\ ailgel, ha\ c clisclo~ccl i ~ l o l r tllnil 200 bone i cmains from qle\ 5eaIs (01 \ I \ 197G),
11 hlch was the second nloqt a b ~ u ~ c l a n t species at the slte Tllc slte has been
Fig. 1. Grey seal localities in Kogaland, Norway.
Table 2 . Surveys of grey seals at Kjer in Rogaland in autumn 1985
Date Method No. of seals References
observed
30 September Boat 36 E L D ~ Y pers. comm.
29 October Boat 15 ELDOY pers. comm.
5 December Aircraft 10 BERGFLODT et al. 1985
9 December Boat 1 1 MUNKJORDET pers. comm.
Table 3. Grey seals collected in Rogaland in 1984.
Locality Sex
Rott Rott Kjar Kolnes Kjer Kjar Kjar Kjer Kj@r Kjar Kiar
8 June 2 September 8 No\~emher 13 November 13 November 13 November 13 November 13 November 13 November 13 November 13 November
Mature NO
YES (foetus) YES YES (foetus) NO NO NO YES YES (foetus) YES NO
Table 4. Grey seal foetuses collected in Rogaland in 1984.
----
Location Date Weight (kg) Length (cm) Estimated
parturition date
Rott 2 September 7.0 66 27 November
Kolnes 13 November 12.5 87 19 December
Kjor 1 3 November 11.5 90 13 December
d a t e d t o 8 000-6 000 B.P. by the Radiological D a t i n g Laboratory, t h e Nor- wegian I n s t i t u t e of Technology, T r o n d h e i m , Norway (HUP I H U I X I E R pers.
c o m m . ) . Pig (Sus s c ~ o f n L.) (49.5OI0) is the o n 1 ~ species which h a s m o r e a b u n d a n t r e m a i n s thatl the grey seal (13.0%). O n l y two o t h e r archaelogical sites h a v e grey seal r e m a i n s of this a b u n d a n c e in Norway, these a r e t h e mesolithic sites c(Kirkehe1leren)) a t T r z n a a n d c(Storb5thelleren)) a t Flak- s t a d ~ y in1 Lofoten. According to D c c r : ~ ~ a r ~ (1 95 1 ) there is n o d o u b t t h a t grey seals b r e d i n t h e neighhourhood of ccVisteh515,). T h e sitr is situated only 2 k m f r o m K j m , w h e r e grey seal p u p s h a v e 1 1 0 1 ~ been recorded.
T h e stock o f grey seals in R o g a l a n d w a s cstimatcd to be 120 specimens i n
1983 (li3~I'rsl..\si) 1983). :\ stock of that nurnl)cr \ \ 7 0 ~ ~ l c l i ~ s ~ ~ a l l y produce 20-30 pups. Tllc k ~ v oI~sc~-\~atioiis o f p ~ ~ p s inclicatr that thr actual up productioi~ is much lolvcl
Grey seals arc not usually fbuncl at the hrcccli~lg site throughout the )-car.
After hrcecling they disperse a n d do not return until tlic next l,reccling season.
Meanwhile they gather at nloulti~lg sites in the spring (c.g., Hc\\.cR 1974).
Most grey scals probably return to breed at tllc rookery of their hirth
boss^:^
1981).
T h r nrarrst hrcccling site of grey scals on tllc Nor\\.egian coast is at Froan.
about 680 kin noi-tll of Iijnr. At this locality 376 P U P S \\.err taggccl in the period fro111 1973 to 1985. 'The s o ~ ~ t l l c r n m o s t I-cco\.rr!. of thcsr pups is at Flor0.
~ t b o ~ t 300 klm north o f K j 0 r (\\'II(; ancl O I C S ill 111-rp.).
Since taggiilg of grey seals in Great Britain \\-as initiated in 1931, a total of 61 scals ha^^ becn rcco~~erecl in Norwegian coastal \vaters (B,JBK(;I: ancl M(:C:OSSEI~.L. 1986). Fifty-eight of these Iverc reco\.c.recl \vithin six lnoiltlls of tagging. i\/lost of the recoxw-ies \\.ere made on the ~vcstcrn coasts fkom Rogaland to Sogn og ~jorclanc. Accorcliiig to HIC:KI~ISC;. R A S ~ I L ~ S S I : ~ . ancl S~11.1.n (1962) and HEIVER (1974) this long distance dispersal is probably clue to xvincl.
T h e immigration fi-om Great Britain is estiinatccl to l l a ~ , c bccn about 14300 seals in the period from 1960 to 1981, a\.craging about 630 grey seals pups per year (QL?R(;I; ancl k~lc:c:oss~:~.r. 1986). These corrcspo~lcl to a production of a stock o f m o r c than 2500 scals, \vhich is nloi-e than 73% of the total S o r ~ v c g i a n polx~lation of grey seals, accordillg to the figures of \ \ ' I I ( ; (1986). There is, however, no information suggesting that British grey scals are heing recruited to Norwegian breeding stocks or are establisliing ilew breeding colonies on tile iVoru~egian coast. T h e f e ~ records of breeding in \vestern S o r ~ v a y during the last 25 years support this. I t is therefore uncertain ~ v h c r e thesc seals actually breed when they becollle mature. According to the results of Nor\vcgian taggings, the lnature grey seals seein to return to their place of birth for reproduction (\.\'rrc; and 011:s in prep.). Soille mixing I~ct~vecll the stocks is.
however, probable. This has been verified in Britain ( H . \ ~ \ v o o u et al. 1976) a n d in Canada (~'I.-\SSFIELD and BEC:I< 1977).
T h e numbers of grey seals observed in Rogaland in the sprillg is much higher than in the brcecling season. I t is rcsonablc, therefore, to assuille that the scals found in Rogalancl in the spring are British and that these return to Britain in the bi-eecliilg season as also suggested 11y B~rnRc;l: ancl ~\ICC:OSSEI.I.
(1986). However, some seals e\~idently clo brcccl in Rogaland, I ~ u t it is uncrrtain ~ v h e t h e r these constitute a local stock or are just occasional young stragglers from the Britisli stocks T h e clatcd lecolcls of foetuses ancl pups suggest n p u p p ~ i l g tlme 111 No\ embcl and Dccernhc.1 in most of the cases 'This 1s later In the \ c a r than aionq most of t l ~ c Xor~\eql'ln co'tst. \ \ h e i r hieccling occurs bet\\ cen S r p t r m b c ~ and Sol c.ml)c~ ( \ \ ' I I ( , 19116)
.lC:KSO\VLEl3CC;\lESTS
I a m grateful t o J . Harulood, Sea k l a m m a Rcsrarcll Unit, Natural Ein-iron- ment Research Council, Cambridge,
B.
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Received 23 April 1986 Pri~itetl 30 April 1987
