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

••

•e•

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

..

••

•••

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

••

•••

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

•

•e•

3.

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

•

•••

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.

•

•••

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.

•••

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.

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 . , ". ~..

••

•e•

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.

••

•e•

9.

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.

••

•••

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.

•

•e•

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

•

•e•

I .

i

12.. -

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~

•

•••

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-

••

•e•

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.

••

•••

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.

••

•e•

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.

ee

•

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

•

•e•

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

,...-------------~---- --------

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.

•

••••