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This paper not to 'be cited withou!-prior reference to the
author
International Council for theExploration of the Sea
C.M. 1982/N:16Marine Mammals Committee
Ref. Marine Environmental Quality Cttee
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BALTIC MARINE MAMMALS - A STATUS REPORT
Lcnnart Almkvist
Section of Vertebrate Zoology. Swedish Museum of NaturalHistory,
P.B. 50007, S-104 05 Stockholm, Sweden
ABSTRACT
Four species of marine mammals are regularly inhabiting the
Kattegat andBaltic areal Among the seals, Harbour, Ringed and
Greyseal are found. Theyhave all seriously decreased in mumbers
this century, the reduction beingprobably 90% or more in the
Baltic. Their geographical distribution hasalso decreased. In the
Kattegat area, including Bohuslän in the Skagerak,more than 3000
Harbour seals exist. Avery small group, 1ess than ~5 Greyseals, is
found in Kattegat. In the Baltic about 200 Harbour seals, about1200
Grey seals and roughly 10 000 Ringed seals remain.
The decrease in number is believed to be the effects of an
earlier huntingand a present very high frequency of female
sterility. probably caused by
PCB.
Under prevailing conditions conservation measures are urgent.
Huntingof seals has been stopped in the nations involved exept
Finland. InSweden a restricted kil1ing'possibility remains. Seal
sanctuarieshave been established, more are in progress •
The only whale found regularly is the porpoise. Their stocks
have 'alsodecreased in numbers. the reasons for this are not clear.
Hunting,weather conditions and PCBeffects have been suggested. The
size ofthe present-day stock is unknown but especially in the
Baltic areavery sm111.
Mink and Otter are also depending on the marine environement in
parts,
of their distribution area - the coasta1 populations. At least
inSweden and Finland the Otter has more orless disappeared from
thecoasts. Hunting and PCS effects are possible causes. The mink
sit-uation is far better, but reproduction is experimantally known
tobe seriously hampered by PCS.
funk-haasNeuer Stempel
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I NTRODUCTl ON
Onlya few marine mammals'are members of the Baltic fauna,
traditionallythree seal and one whale species. In especially the
last decades therehas been a drastic reduction in numbers of these
species. This has pro-voked protective measures in legislation, a
number of investigationsin various fields and increasing
cooperation with scientists in neigh-bouring nations. The most
important result hitherto is without doubtthe discovery of a
reproductive malfunction in seals, leading to avery low natality.
This i5 probably an effect of tao high levels ofPCB in the seals
and in that case it reflects a severe ecological effectof
man-inflicted environmental pollution.
In this synopsis. data on Baltic seals and whales are given.
Emphasisis given on their present status. Same comments are also
included onotter and mink as they in some aspects parallell the
marine species.
In the following the Baltic area is defined as the ßaltic proper
andthe Gulfs·of Finland, Riga and Bothnia. The Kattegat area is
treatedseparately. This separation is done because of the different
environ-mental and pollution conditions of the areas. leading to
differentp~pulation conditions.
SEALS (Pinnipedia)Three different species of seals regularly
inhabit the Kattegat andBaltic area. They were earlier valuable
hunting animals in many coastalareas. Nowadays the stocks are
small/very small compared to earlierconditions and various measures
have been taken to protectand ifpossible to save the seals.
especially in the Baltic area, where theconditions are worst .
Harbour seal (Phoca vitul~na)The harbour seals (Common seal) of
the Kattegat and Baltic area belongto the nominate subspecies. This
is found in Ieeland. the British Isles,the Netherlands, West
Germany, Denmark, Sweden and Norway as breedingpopulations. The
total stock probably amounts to some 75 000, of which
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2.
50 000 - 60 000 are found in Iceland and Great Britain. On,the
coasts·from Belgium -'western Denmark some 5 000 Harbour seals are
found. Inthe Skagerak/Kattegat/Baltic area perhaps 3 500 are found
and inNorway about the same numbers have been given. (Bonner 1976.
Summers1979. Data from European Seal Group meetings 1979. 1980.
1981).
Kattegat areaIn this area. harbour seals have decreased in
numbers since at least1750 (S~ndergaard et a1 1976). Recent
investigations have shown thatmigrations take place between the
Kattegat and the Skagerak area.which makes it natural to include at
least the seals in Bohus1än.NWSweden. with the Kattegat group
(Härkönen 1982).
In Norway, only sma11 numbers remain in the Skagerak parts,
perhaps. ,
on1y a few hundred anima1s. (~ynes 1966) Thelargest group
(Hva1er) hasnowadays decreased to same 30,(Härkönen
pers.comm.).
It is be1ieved that the stock in Kattegat/Bohus1än numbered
some. 10 000 around 1890, and probab1y not less than 1000-1500 in
the mostcritica1 years 1940-1965.'Today the stock consists of more
than 3000seals. About 750 of these are found in Bohuslän. In the
Kattegat areaabout 900 are found in Swedish an~ about 1500 in
Danish waters (Härkönen1982).
Since protection in Swedenin the mid-60s, an increase in numbers
hastaken p1ace. Indications of a 10w reproduction resu1t have been
foundin several sea1groups of the area. Various causes have been
suspectedor identified, as high juvenile morta1ity due to bacteria1
infectionsand/or disturbance (Heide-JDrgensen 1980) and incidental
ki11ing infishing gears (unpubl.). Loca11y, the peB levels are
comparab1e to theBa1tic situation and female sterility might be
present. Fema1es withocc1uded uteri have been found in the area.(M
01sson pers.comm.). Insome places the seal groups seem to be low in
adu1ts, resulting ina low frequency of pups (Härkönen 1982).
Studies on feeding habits in Skagerak have shown a predominance
ofeod, flounder and herring species. Seaso~al differences in food
speciesintake are distinct. The seals feed mostlyon specimens less
than 30 cm
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in length. Their competition with the human fishing industry was
con-sidered to be 1imited (Härkönen 1982).
Ba1tic areaIn contrast to the other Baltic seals, the harbour
seal is the whole yearbound to the coasts. They scatter during 1ate
autumn-spring, but accumu-late on their breeding areas in
summer-ear1y autumn. The fema1e givesbirth to one pup in 1ate June
- early August, then mating and a moultingperiod takes p1ace. The
breeding areas in the Ba1tic are she1tered beachesand sma11
is1ands, often sandy •
Their food species in the Ba1tic is not we11 known, but consists
probab1ymost1y of fish. In a sma11 material of stomachs, ee1 and
f10under wasfound as wel1 as sma1ler quantities of eod, turbot,
whitefish and Myti1us.
The distribution area of Harbour seal has decreased in the
Ba1tic; andthey are now regular in Denmark and Sweden on1y.
InSweden they are foundin three areas: Falsterbo, southern
Kalmarsund and southern Got1and. AtFa1sterbo they main1y occur at
Mäk1äppen, where around 50 harbour sealscan be found. In southern
Kalmarsund also about 50 seals occur in threedifferent 10ca1ities.
The number of harbour seals on Got1and are uncertain,probab1y less
than 10 specimen remains. (Almkvist et al 1980).
The decrease in numbers in the Kalmarsund area has probably been
at least90 % since the 20s. In southern Sweden bounties for about
2500 killedHarbour seals were paid in 1925-1959. About half of the
number were youngseals. This indicates that hunting has been a
major cause to the stockreduction (A1mkvist et al 1980).
In Denmark very few harbour seals remain, probab1y 1ess than 100
anirnalscan be found around southern Sjae11and, where R~dsand is a
c1assic seal
" area (S0ndergaard et a1 1976, Heide-J0rgensen 1980). The total
Ba1ticgroup is probab1y on1y some 200 animals. It is un1ike1y tha~
they mixto any extent with the population in Kattegat.
The reproduction resu1t of Baltic Harbour seal is not well
known. In
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4.
the Falsterbo and the Kalmarsund area pups are known to be born.
Noted .numbers of pups are however not quite representative of a
vital popula-tion - this might.however be an artefact of too scanty
information. Itshould be noted that afew cases of adult females
with uteri occlusions tand thus sterile t are known from the Baltic
Harbour seals. In the Falster-bo and the Kalmarsund areas censuses
in 1975-1981 do indicate constantor possibly slowly increasing
groups (Almkvist unpubl.). The breedingareas have restrictions in
public admittance t important as vacation. .time coincides with the
pupping season.
Grey seal (Halichoerus grypus)The grey seal is divided in three
separate populations t confined to thenorthern Atlantic area. In
eastern Canada and NE USA the Western Atlanticpopulation comprise
over 20 000 seals (Banner 1979, Mansfield &Beck1977). The
Eastern Atlantic population is centered around the BritishIsles,
where over 70 000 seals are found (Summers 1978). The third
po-pulation t the Baltic. is nowadays found only in the Saltic.
Ka ttega t area;,The information on the present-day group of
grey seal in this area isvery limited. On1y very few seals are
reported t .the total Kattegat groupwas in 1979 estimated to be
less than 25 animals (Heide-J~rgensen 1979).It is be1ieved that the
group has emanated from the expanding EasternAt1antic grey seal
population, which:in many ways is different from theBa1tic
population. For instance they are autumn-breeding, not
spring-breeding. The two populations are in all probability
genetica11y iso-
. .lated and different .
In ear1ier days the Baltic seal population expanded into the
Kattegattwhere e.g. Anholt was an important breeding area. They
decreased muchin numbers during the 19th century and probably
disappeared from Kattegatin the beginning of our century
(S~ndergaard et al 1976).
Baltic areaIn the Baltic, grey seals are nowadays found along
the shores of Sweden,Finland and USSR. Here they inhabit isolated
areas in the outermostparts of the archipel agas. where they often
rest on small skerries androcks.
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5.
They mostlyleave the coast during the winter, when they migrate
toreproduction areas on drifting iee in the Baltic open .sea. Their
pupis born in February-March and is left after about one month of
nursingand suekling. Mating probably takes plaee in the iee areas,
followedby aperiod of annual moult in April-May, which mostly takes
place onthe coasts.
Among examined adult females from the Swedish coast, about one
half wasfound to be sterile due to uterine ocelusions. This
indicates that thenumber of pups born is abnormally low in the
Baltic. This is also suppor-ted by the very few available field
data (Bergman et al 1981) •
The Saltic Grey seal feed almost exclusively on fish species,
especiallyon salmonids. herring and eod. all speeies with a
relatively high contentof fat. Their daily intake varies in the
year, being lower in spring andhigher in autumn, when their blubber
layer is building up. As a meandaily intake 7 kg has been given
(Almkvist et al 1980).
Among fishermen. the seals had a bad reputation, as they
destroyed fishingequipment and catches of fish. Especiallythe
salmon and herring fisherieswere damaged by the grey seal. This
conflict led to the introduction of abounty system in many Baltic
nations at the turn of the century, thusencourag ing the seal
hunt.
Investigations on damage caused by seals on the fishing industry
carriedout in Sweden and Finland in the 60s and 70s have shown that
the salmonfisheries suffered negligible losses (a few percent) as a
rule. Locally,however, and especially earlier the damage could be
substantial (Almkvistet a1 1980, Stenman 1978).
Hunting of grey seals in the Baltic has taken place sinee
prehistoricaltimes, and was locally of importance' also in this
century. Especiallyhunting on the breeding areas in the northern
Saltie (Bothnian Bay andBothnian Seal could give a good result. In
these areas the seals, beingon international waters. was hunted by
Swedish and Finnish coastal in-habitants. In 1932-39. when the iee
situation probably was favourablefor hunting, some 30 000 grey
seals were kil1ed, about 20 000 of thesebeing pups. Up to 10 000
grey seals could be killed in one year as in 1913.The high
frequency of pups and probab1y also of adult females in thehunt
must seriously have affected the population.
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6.
The Baltic grey seal has decreased very much in numbers this
century,from perhaps around 100 000 to one or two thousands. This
is also re-flected on the coasts, where many traditional grey seal
skerries nowa~e deserted, e.g. the famous Harstena seal skerries in
Sweden, whereseveral 10 OOOs of grey seals could be seen in the 30s
(Almkvist et al1980).
Along the Swedish Baltic coast, grey seals now are found at some
20different places, often widely separated. Very rarely more than
onehundred grey seals can be counted in one locality. The total
stockamounts to about 750 animals. Most places with regular
occurrence ofmore than ten animals are protected as sanctuaries.
See also the mapon p. 7.
In USSR, the number of grey seals is very low nowadays. In 1977
110animals were observed in the Bay of Fin1and and
Riga(Datapresentedby Dr 0 0 Tormosov at the Warzaw seal symposia
1980). In 1980 thenumber of grey seals,hauling out on skerries
during summer-autumn in·these areas,was estimated to 100
animals.(Anon 1981).
Also in Fin1and, the grey seals have decreased in number this
century(Nieme1ä 1974, Stjernberg 1975). They are still found in
small groups inthe Aland/Aboland area andthe eastern parts of the
Gulf of Finland.Along the Bothnian coasts there seems to be no
regular summer occurrences •Larger concentrations - of some·SO-100
animals - are rare. In the last fewyears, the seals are seen in
larger groups than before and are nowadaysless shy. Also young
seals are part of the groups. The total number ofgrey seals in
Finland is estimated to some hundreds, probably around 300(Stenman,
Stjernberg pers.comm.).
Summarizing, it is evident that the grey seals are scarce in the
Ba1tictoday. The population is in summertime distributed over wide
areas, haulingout on their traditional·skerries in small groups.
Some 30 groups of morethan 10 grey seals are known. In five areas
the flocks consist of morethan 100 seals. It should be noted that
two of these areas are binational,A (Sweden/Finland) and B
(Finland/USSR). The to~al Baltic population mightbe estimated to
about 1200 heads, based on available information. Inclu-ding
reasonable inaccuracy the population number estimate is better
givenas 1000 - 1500 sea 1s.
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7...
about 10about 25about 50more than 100
••&
Letters indicate the five largestconcentrations. The size
classifi-cation is crude. For referencessee text.
Summer distribution of Grey sealin the Balt;c area
1979/1981.
"
\' ",~~, '...
....l ",
.~ '.
I......, ,
, >
fI . , ". ~..
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8.
Ringed seal {Phoca hispi~This circumpolar, more or 1ess arctic,
species is one of the mostabundant of northern seals. The Ba1tic
population, iso1ated fromthe main stocks, is considered to be
aseparate subspecies (Phoca.hispida botnica). Ringed seals have
also been iso1ated in the LakeSaimaa and Ladoga, constituting the
subspecies saimensis and lado-gensis. Ringed seals are only
sporadieally noted in the Kattegat orSkagerak area.
In the Ba1tic area. the population area of distribution has
decreased •Earlier this eentury they were found in the central
archipe1agos ofSweden, but now oeeur only sporadically. The
population also has de-ereased in numbers in the Ba1tic area. from
perhaps severa1 100 OOOsto perhaps 10 000 (A1mkvist et al
1980).
Although the ringed seal is the most numerous in the Baltic, it
isoalso in some aspects the least known. Estimates on their numbers
havebeen made on iee in the Bothnian Bay (Helle 1980) and in the
Gulf ofFinland and Riga (Anon 1981). A total of roughly 10 000 has
been given(A1mkvist et al 1980, Helle 1980). This value is a crude
estimate ofthe size of the Baltic ringed seal population. whieh is
very difficu1tto census.
In their biology they are similar to the grey seal. but are
smallerand live more solitary. They breed on sea-ice in 1ate
winter. chosingmore solidified iee. where one pup is born. often in
eaves in crackridges. Their food intake is lesser than the grey
seals. Herrings andsalmonids are important. as are crustaeeans
•
The ringed seal was the most important of the three Baltie
species inhunting. Large numbers were killed. especial1y in the
reproduction areas.In the 19105 more than 100 000 ringed seals were
killed by Swedish andFinnish hunters. ineluding a large portion of
young seals (A1mkvist etal 1980).
The severe drop in reproduction rate of Baltic seals was first
notedin ringed seals from the Bothnian Bay. This reduetion is
believed tobe.the primary cause to the decrease in numbers in the
last decades.
when hunting beeame of less importanee.
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Lowered reproductive rate in Saltic seal~In 1974 laboratory and
field investigations on Baltic seals led to ahypothesis that DDT
and PCB might influence the reproduction (Olssonet ale 1975). Low
reproductive rate was reported in Ringed seal fromthe Bothnian Bay
(Helle 1975). Later they reported higher.levels oforganochlorines
among non-pregnant adult females than among pregnantfemales (Helle
et al. 1976a). Comparisons with other data and experi-ments on mink
has led to the assumption that peB is the responsiblesubstance
(Jensen et al. 1977) .
It was also found that adult females had occlusions in the
uteri, apathological condition implying sterility (Helle et ale
1976b). Thefrequency of the occlusions is high, having increased in
the lastfive years to 60 %in Ringed seal from the Bothnian Bay. The
proportionof pregnant females decreased from over 30 %to less than
20 %duringthe same period. These values are the lowest recorded
anywhere in aseal species. (Helle 1980). High frequencies of uteri
occlusions werenoted in Harbour, Ringed and Grey seals from Sweden
(Sergman et ale1981). Uterine occlusions have now also been noted
in Grey and Ringedseal from the Gulf of Finland (Stenman,
pers.comm.), in Harbour sealfrom the Skagerak/Kattegat area
(Bergman et al 1981).
The mechanisms behind the uterine occlusions are not known. It
repre-sents a formerly unknown mammalian pathological condition.
Studies onthe pathology have now started in cooperation between
Sweden and Fin-land. Preliminary results indicate pathological
changes also in organsother than the uteri. e.g. in the kidneys
(Bergman et ale 1981).
The direct effect of the low reproductive rate is the production
ofvery few pups compared to normal conditions. It is believed that
femaleswith PCS levels above some limit will acquire occluded
uteri. A portionof the newly matured females will thus soon become
affected, accumula-ting PCB through their life. The effects are
carried on to the nextgeneration, as the newborn pup receives PCS
from the mother.
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10.
The effects of the 10wered reproductive rate is en1arged by a
highmorta1ity of young seals. Some 20-30 % of the born grey seals
diebefore the age of 6 months, most1y by drowning in fishing gear
(A1m-kvist et al. 1980).
In a hypothetical discussion, using known data, it was shown
that ina population of 2000 seals on1y 160 pups were born annually.
Whenthese pups reach maturity, only 12 of them will be fertile
females.Although this is a crude model, the seriousness of the
Ba1tic condi-tion is indicated. The surviva1 of the Ba1tic seals is
definitelyendangered, if the reproductive rates continues to be low
(Almkvistet a1. 1980) .
Protection of the Baltic sealsIn the Kattegat area hunting is
forbidden in both Danish and Swedishwaters. In the Baltic area
hunting in Swedish waters was stopped.from1974 (A1mkvist et al
1980). In USSR hunting of grey seal was bannedin 1975 and of ringed
seal in 1980 (Anon 1981). In Finland hunting ofgrey and ringed seal
is forbidden in the Aland waters since 1981. Inthe other parts of
Finland hunting of grey seal is prohibited since1982. when the
hunting of ringed seal was limited to the period march20 - june 10
(Stenman pers. cemm.).
In Sweden professional fishermen have a legal right to kill
seals foundby chance during fishing. This possibility has now been
questioned •
Special areas where admittance is prohibited, seal sanctuaries,
havebeen established in Denmark (a few), Sweden (35) and USSR (a
few) toprotect the seals from direct human disturbance. Further
sanctuariesare planned in Denmark, Sweden, Finland and USSR. On the
Swedish Balticcoast 22 sanctuaries cover about 300 km2 land and
water areas. Publicadmittance is forbidden the whole year or the
greater part of the year.In the sanctuaries a buffering zone of
about one km is often used. basedon the shyness of grey seal.
Sea1 researchThe severe situation for these animals in the
Baltic area has led scientists
to concentrate on problems with a bearing on the surviva1 of the
species.
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11.
The numbers of seals are fo110wed to detect trends of e.g.
further dec1ineor shifts in distribution. Analysis of the levels of
various pollutantsare earried out with the same purpose and to be
ab1e to study harmfuleffects on the seals of e.g. PCB.
ßased primarilyon accidenta1ly ki11ed seals, their pathology is
studiedto get an understanding of the meehanism behind uterine
ocelusions andto describe the patho10gy and parasitology of the
threatened populations .
In order to establish adequate protection and 1egislation in the
future,the possib1e eauses for the population ~eelines are
analyzed, consideringfactors such as hunting, disturbance, iee
conditions, nutrients and pol 1u-tants. Scientists also aid in
establishing seal sanetuaries and in otherprotection actions.
In Sweden future breeding of grey seals is prepared by the start
of apilot breeding area in Uppland, where at the moment four seals
are.kept.
Seientists meet regu1arly to diseuss recent and planned
aetivities. Theseals of the Kattegat area are represented on
meetings of the EuropeanSeal group. Their latest meetings were held
in the Nether1ands 1977,in West Germany 1978, in Sweden 1979. in
England 1980 and in Denmark1981. The Baltic problems are discussed
in Baltic Seal Symposiums, heldin Sweden 1974. Fin1and 1977 and
Poland 1980 .
WHALES (Cetacea)
Several different whale species have been recorded in the
Kattegat andBaltic area. In this paper only the porpoise is
eommented upon. Recordsof other speeies found in the Ba1tic area
since 1960 are summarized inan appendix.
E~oi~~lPhocoena phocoena)This is a small whale species found in
most coastal areas in the northernhemisphere. In the North
Sea/Baltic area their numbers have decreased,possible eauses being
hunting, incidental killing, reduction' of the stocks
of their. food species and pollution effects. In the Baltic area
effectsof severe ice-winters might have contributed to the decline.
High content
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of peB in porpoise have led to a suspicion that the reproduction
mightbe affected as in Baltic seals (Otterlind 1976).Hunting of
porpoisehas 10ng traditions in the area, reaching into the middle
ages. In Dcn-mark the porpoise was hunted as late as during the
second wor1d war.Based upon hunting statistics Mitchell (1975)
estimated the total Balticstock of porpoise to 10-15 000 in the
last century.
The base for much of the Swedish and Danish hunting was an
annual mig-ration in and out of the Baltic at Lillebaelt and
öresund. These migra-tions have nowadays more or less disappeared
(Andersen 1976) and in theBaltic proper a drastic reduction' of the
stocks has taken place (Otter-lind 1976). eonsidering the very few
strandings and sightings in thelast years, it seems l~kely that the
porpoise no longer is a regularinhabitant of the Baltic (Otterlind
pers comm).
Investigations are now carried out in a Swedish/Danish
cooperationproject. Findings of heavily parasite-infested porpoise
have beennoted (Olsson pers.comm.).
MUSTELIDS(Muste1idae)
Among the muste1ids of the area, two species are to a large part
waterdependent, the mink and the otter. They are both found near
fresh andmarine waters, and also a10n9 the Baltic coast. They are
of specialinterest, as they are depending of the production of the
coastal zone,ahd thus exposed to the pollutants in the marine
ecosystems here •
Mink (Mustela vison)
Introduced to European nations from North America in this
century •primarily into mink farms, for production of a valuable
pelt. In Swedenthe first mink farm was established in 1928. After
the second wor1d warthe numbers of farms increased rapidly. Runaway
minks form the farmshave established wild populations. and have
been hunted since thestart. In the late 60s, catch statistics
indicate that about 20 000minks were kil1ed annua11y. The mink had
by then colonized the who1eof Sweden except the northernmost part
(Gere11 1972).
Minks are now found a10n9 fresh 'waters in the inland, but also
a10ngthe coasts of Sweden.and Finland. Their prey constitute both
fishes~
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13.
sma11 crustaceans, frogs, sma11 mamma1s and water birds. They
part1yfeed by diving.
On the Ba1tic coasts, minks have been b1aimed for damage on
va1uab1efish and bird populations, e.g. same auks and eider.
A1though thishas not been investigated in detail, campaigns against
the mink areoften 1aunched. Mink has also been accused for the
decrease of otters,hut it is not be1ieved that they have been a
major factor (Erlinge 1972).
Contro11ed experiments on the possib1e effects of PCB and DDT on
mink,reproduction have c1early shown that PCB does have a negative
effect.Intake of peB. also in sma11 amounts, 1ed to a reduction of
the numbersof born minks. Affected females had a PCB level above 50
mg/kg in fattissue.
It was also observed that the frequency of de1ivering bitches
decrease,but the number of implantation sites was not significantly
lowered~
. Also the condition of the young born was 10wered (Jensen et
a1. 1977).It was observed, that PCB-treated animals had a higher
cadmium levelin the kidneys tha~ contro1s, indicating a
synergistica1 accumulation(Olsson et a1; 1979).
A10ng the Swedish Ba1tic coast, the numbers of mink probab1y
droppedin the ear1y 70s, but they have increased again in the last
2-3 years(R Gerel1 pers.comm.). It is not un1ikely that this
reflects the effectsof a decrease in the Ba1tic PCB levels, which
recent1y was reported(Bergman et a1. 1981). Minks. which has a
rapid generation turnover.young ~nima1s being fertile in~heir first
year of 1ife, should respondre1ative1y fast to a decrease of
natura1ly occurring PCB (M 01sson pers.comm.).
~tter (Lutra 1utra)In Sweden, the population of otter has
decreased since about 1950. Afternational censuses in 1975/77. the
total population was estimated to atleast 1000-1500 anima1s
(Erlinge 1980).The number of otters thus equa1sthe year1y catch in
the years around 1950 (Erlinge 1972). Since1968hunting of otter is
prohibited.
The previously wide-spread population on the Swedish Ba1tic
coast ha~also decreased severely. In many coastal areas. the otter
now has dis-
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14.
appeared or is very rare. Small numbers of otters have been
reportedfrom the coasts and archipelago in southern Sweden, but
along thenorthern coast1ine, the otter now perhaps has disappeared
(Erlingepers .comm. ) •
In Fin1and a corresponding drastic decrease has taken p1ace in
thecoasta1 areas. The stocks are now very sparse and low in
numbers(Stjernberg pers.comm.).
In a first check on the levels of organoch10rines (Sandegren et
a1. 1980)it was found that Swedish otters had high levels of PCB.
the mean levelwas 120 mg/kg. Otters from the coasta1 regions had
mean levels of 190mg/kg. This was compared with data from the vital
population along thenorthern Non~egian, where the mean levels were
17 mg/kg. As reproductioneffects occur in mink at levels above 50
mg/kg and as the otter levelsare higher, it was conc1uded that it
is quite possible that the reproduc-tion of otter might be
affected.
Since 1975 a II project Otter" is working in Sweden, sponsored
by WorldWildlife Fund and the Swedish Sportsmen's Association. The
projectfol10ws the size of the Swedish otter population. tries to
identifycauses for the dec1ine and also runs a breeding research
plant of 20hectars at Boda Wildlife Research Station. established
in 1978 .
REFERENCES
Aguayo, L. 1978. Smaller Cetaceans in the Ba1tic.
Rep.Int.Whal.Comn. 28:131-146.
A1mkvist, L., M. 01sson , and S. Söderberg. 1980. Sälar i
Sverige.Svenska Naturskyddsföreningen, Stockholm.
Andersen, S.H. 1976. Change in migratory behaviour in the
harbourporpoise, f~o~oen~__~hocoen~. FAO Sci. Consult Bergen,
paperACMRR/MM/22.
Anon. 1981. Marine Hammals Committee, Administrative REport
1980, USSR.lCES C.M. 1981/N:l.
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15.
Bergman, A., .M. Olsson, and L. Reutergärdh. 1981. Lowered
reproductionrate in seal population and PCB. A discussion of
comparability ofresults and a presentation of some data from
research on the Baltic
seals. lCES C.M. 1981/N:l0.
Bonner, N. 1976. Stocks of Grey seals and Common seals in Great
Britain.Natural Environm.Rcs.Council, Publ.Ser. C, No. 16.
Bonner, N. 1979. Harbour (Common seal). In: Mammals in the seas.
FAOFisheries Series 5, vol 2: 58-62.
Bonner, N. 1979. Grey seal. In: Mamma1s in the seas. FAD
Fisheries Series
5, vo 1 2: 90-94.
Erlinge. S. 1972.The situation of the Otter population in
Sweden.
Viltrevy 8: 3:379-397.
Erlinge. S. 1980. Die Rückgang der rischotterpopulation in
Schweden.In: Reuter, C. &A. Festetics (Eds.) 1980: Der
Fischotter inEuropa - Verbreitung. Bedrohung. Erhaltung. Göttingen.
pp 103-106.
Gere11. R. 1972. Mink. En artmonografi. Stockholm, Bonniers. 95
pp.
Heide-J~rgensen. M-P. 1980. Saelbestandene i de danske farvande.
~:Status over den danske plante- 09 dyreverden,
Fredningsstyrelsen,
pp. 292-306.
Helle, E. 1975. On the bio10gy of the ringed seal ~~~ hi~}d~ in
theBothnian Bay. National Swedish Environment Protection Board,
PM
591: 38-42.
Helle, E. 1980. Reproduction. Size and Structure of the Baltic
ringedseal population of the Bothnian Bay. Acta Univ. Ouluensis
sero Ano. 106, 47 pp .
Helle. l., M. Olsson, and S. Jensen. 1976. DDT and PCB levels
and repro-duction in ringed seal from the Bothnian Bay. Ambio 5
(2):188-189.
Helle, E•• M. Olsson. and S. Jensen. 1976. peB levels correlated
withpathological changes in seal uteri~ Ambio 5 (5/6):261-263.
Japha. A. 1908. Zusammenstellung der in der Ostsee bisher
beobachtetenWale. Schriften Phys.-Ukon.Ges. Königsberg in Pr.,
49:119-189.
Jensen. 5., J.E. Kihlström, M. 01550n. J. Urberg. 1977. Effects
of pesand DDT on mink (~~~_~~~~~~~~~)during the reproductive
season.
Ambio 6 (4):239.
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16.
Lepiksaar, J. 1966. Zahnwal funde in Schweden. Bijdragen tot de
Dier-
kunde 36:3-16.
Mansfie1d, A.W. and B. Beck. 1977. The grey seal in eastern
Canada.Dept of Fisheries and Environment,Fisheries Marine
Service,
Techn.rep. 704.
Mitchel1. E. 1975. Porpoise, do1phin and sma11 whale fisheries
of theworld, status and problems. IUCN t10nographs 3, 129 pp.
Niemelä. E. 1974. /The Grey Seals of the Ba1tic/ Suomen Tuonto
1974:
241-2461
01s50n, M.• A.G. Johnels, and R. Vaz. 1975. DDT and PCB levels
in sealsfrom Swedish waters. The occurrence of aborted seal pups.
NationalSwedish Environment Protection Board, PM 591:43-65.
01sson, M., J.E. Kih1ström. S. Jensen, and J. örberg. 1979.
Cadmiumand Mercury concentrations in Mink (Mustela viso~) after
Exposuu€
to PCßs. Ambio 8 (1):25.
Otterlind. G. 1976. The harbour porpoise (~~~co~~~JP-~~~~~)
endangeredin Swedish waters. ICES C.M. 1976/N:16.
0ynes, P. 1966. Se1 i S0r-Norge. Fiskets Gang 1966:834-839.
-Sandegren. F., M.Olsson, and L. Reutergärdh. 1980. Der Rückgang
derFischotterpopulation in Schweden. In: Reuter, C. &A.
Festetics(Eds.) 1980: Der Fischotter in Europa - Verbreitung,
Bedrohung,Erhaltung, Göttingen. pp 107-113.
Schultz. W. 1970. Ueber das Verkommen von Walen in der Nord- und
Ostsee(Ord. Cetacea). Zool. Anzeiger 185:172-264.
Schulze. G. 1976. Die Wal funde aus dem Bereich der OstseekUste
der DDR.Natw' Natur'schutz Hecklenburqll :97-112,
Stenman. O. 197B. llamage caused uy seals to salmon fisheries in
Fin1and1974-1976. Finnish Game Res. 37: 48-53.
Stjernberg, T. 1975. Gräsälen. Finlands natur 34: 26-28.
Summers. C.F. 1978. Trends in the size of British Grey seal
populations.J.App1. Ecology 15: 395-400.
Summers. C.F. 1979. The scientific background to seal stock
managementin Great Britain, Natural Environm.Res.Council. Publ.Ser.
C. No. 21.
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17.
APPENDIX
Uha'Le_SJ?.~E.ie..~J_o~nd in the Baltic area since 1900
Since 1900 about 13 different whale species have been reported
fromthe Baltic. Of these all but the porpoise must be considered as
veryrare visitors in the area, only known from a few findings of
strandedwhales. It is however not impossible that small flocks of
some ofthese species might be trapped in the Baltic. In this way a
localgroup might be formed, which also might reproduce in the
Baltic.There are some indications that trapping sometimes takes
place.The bottlenosed dolphin and the white-beaked dolphin are
probablythe two species that are "nearest the Saltic", but the
Beluga shouldalso be mentioned. This is an arctic species which in
cold wintersoccasionally enters the Saltic, as in 1903 and 1964,
and managesto remain for a few years.
A list is presented below of the whales found in the Balticsince
1900 excluding the porpoise. The number of records from Denmarkand
West Germany are added and listed as western Baltic records.
Re-cords from DDR, Poland and USSR are presented under East Baltic.
Thelist is based upon Aguayo 1978. Japha 190 • Lepiksaar 1966,
Schultz
1970, Schultze 1976. and recent unpub1ished records from
Sweden.
Dolphi1!(Delphinus delphis). Sweden: 1956 a female near Arho1ma
in Uppland
Bottlenose.dolphin (Tursiops truncatus)WBaltic: 9 recordsE
Ba1tic: 1960 near Stra1sund in DDRFinland: 1906 a female near
Hangö
White-beaked do1phi~ (Lagenorhynchus albirostris)Sweden: ~937
near Ahus in Skäne
1974 a fema1e near Söderhamn in Hä1sing1andWBaltic: 4 records.E
811tic: 1975 a female near Stra1sund in DDR
Killer-~hal~ (Orcinus orca)Sweden: 1926 ca 40 km off S;mr~shamn
at sea-bottom,skeleton parts
1932 ca 20 km off Simrishamn at sea-bottom.ske1eton parts
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18.
WBaltic: 1919 at Fyn, Denmark1943 at Sönderborg, Als,
Denmark.
Rissos dolphin (Grampus griseL6)WBaltic: 1937 at Lolland,
Denmark
Be1ug~ (Delphinapterus leucas)Sweden: 1966 a male near Umeä in
Västerbotten
1966 a fema1e at Gräsö in UpplandWBaltic: 1903 in
F1ensburgfjorden, DenmarkFinland: 1903 at KalajokiE Ba1tic: 1906 a
skeleton near Pernau in USSR
1908 a male near Memel in USSRIn 1903-1908 and 1964-1966
sightings of Beluga ~las reported fromseveral p1aces in different
areas of the Baltic.
Sowerby"s beake~ wh~~ (Mesoplodon bidens)WBa1tic: 1966 at Aerö,
DenmarkE Ba1tic: 1913 at Greifswald, West Germany
1935 at Woll in. Po1and
Bo~tlenose whaL~ (Hyperoodon ampullatus)WBa1tic: 1957 at
Kopenhagen, Denmark
1959 at Store ßae1t, Denmark
Finwha1~ (Balaenoptera physalus)Sweden: 1923 at Lövsta in
Upp1andWBaltic: 1911 at Flensburg, WGermany
1943 at Flensburg, WGermany1958 at Lo11and. Denmark
Sei whal~ (Balaenoptera borealis)WBaltic: 1955 at southern Fyn,
Denmark
Minke whale (Balaenoptera acutorostrata)Sweden: 1965 in
Kalmarsund. öland. Stranded and escaped.WBaltic:1918 at Lille Baelt
area, Denmark
1928 at Glücksburg, WGermany
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19.
E Baltic: 1953 by Usedom, DDR
•Humpback wha1e (Megaptera novae-angliae)Sweden: 1979 sightings
at several p1acesFinland: 1979 sightings alsoE Ba1tic: 1979 off
Rügen, sightingsPossibly the same specimen observed at various
places in the Baltic.
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