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.. ~- This paper not to be cited without prior reference to the authors International Council for the C.M. 1982/M:38 Exploration of the Sea Anadromous and Catadromous Fish Cornmittee

RESULTS OF STOCKING WITH BALTIC SALMON IN FINLAND IN,,1969-1980 by E. Ikonen and H. Auvinen Finnish Garne and Fisheries Research Institute Fisheries Division, P.O. Box 193, SF-00131 Helsinki 13, Finland

Abstract

This paper deals with tagging experiments carried out with salmon in Finland in 1968 - 1980. The stocking results in the Bothnian Bay area vary between 1 and 1367 kg per thousand smolts released, averaging 372' kg.·' The best smolt year , . classes were those of 1972 arid 1973. The ~almon stocks ,. . ~\ originating from rivers in the Bothnian Bay migrate to the • southern Baltic Sea and Gulf of Finland, the stocks of the Bothnian Bay area migrate long, distances, whereas the river Neva stock (Gulf of Finland) has a rather restricted migration area.

Resurne '

Cet expose traite l'experience d'etiquetage faite sur le saurnon en Finlande de 1968 a 1980. Les resultats de l'alevinage dans la zone du golfe de Botnie varient entre 1 et 1 367 kg pour mille smolts relaches. Le resultat moyen a ete de 372 kg. Les , meilleures classes annuelles de smolts ont ete celles de 1972 et de 1973. Les peuplements de saurnon originaires des fleuves se jetant dans le golfe de Botnie migrent vers le sud de la mer Baltique. Selon les experiences faites dans le golfe de Botnie et'dans le golfe de Finlande, les peuplements du golfe de Botnie migrent dans le sud de la mer Baltique, tandis que le peuplement du fleuve Neva'(golfe de Finlande) a une zone de migration tout a fait reduite. 2

Introduction Finland has sea coasts on the Gulf of Bothnia, Archipelago Sea and Gulf of Finland, all of which form the most northern parts of the Baltic Sea. More than 60 rivers flowing from Finland to this part of the Baltic Sea have supported migratory fish stocks (HURME 1962, 1970, MÄKINEN 1972, SJÖBLOM et al. 1974, .CHRISTENSEN & JOHANSSON 1975, TOIVONEN & IKONEN 1978, , CHRISTENSEN & LARSSON 1979,, LEHTONEN & HILDEN 1980, TUUNAINEN et al. 1979, 1980 and HILDEN et al. 1981), and 18 of the rivers have supported salmon runs (CHRISTENSEN & LARSSON 1979). The demand for hydroelectric power has caused almost total destruction of the salmon stocks in these salmon rivers. The biggest and most important salmon rivers have been the Kemijoki, Oulujoki, Tornionjoki, Iijoki, Simojoki (ICES sub-division 31), Kokemäen• joki (ICES sub-division 30) and Kymi (ICES sub-division 32). Nowadays only the Tornionjok~ and Simojoki support salmon runs. Earlier, the Finnish rivers producedabout 2.54 million smolts • a year (SJöBLOM et al. 1971); nowadays the salmon smolts produced in the remaining Finnish salmon rivers number about 67 000. To compensate for the lost smolt production, artifically reared salmon smolts have been released in the mouths of the old salmon rivers since 1959. Up to 1977 the number of smolts released annually has been around 100 000. Later, the numbers have increased rapidly: in 1981 the number of smolts released was 733 000; in 1985 the number will be more than one million. Apart of the smolts have been tagged. This paper gives abrief report of the results oftagging experiments undertaken in , 1969-1980 to evaluate the success of salmon stocking off the coast of Finland •

• Material and methods In 1969-1980, a total numberof 116 000 smolts was tagged in 149 experimental groups. ,The,mean.number of smolts tagged in each experimental group was 779, the group sizes usually being 2 000, 1 000, 500 and 250. The length of the two- or three­ year-old smolts varied between 13 and 22 cm (usually 14 - 17 cm). In the Bothnian Bay area,all.the tagged fish were reared artificlallyand the eggs were mainly produced by artificially 3

reared spawners.The stocks originated from the rivers Iijoki, Oulujoki and Tornionjoki. In the Bothnian Sea area, the stocks originated from the rivers Iijoki.(Finland), Angermanälv, Dalälv (Sweden) and Neva (USSR). In the Gulf of Finland, mainly Neva stock was used. The smolts were usually tagged in spring, some days before release, by taggers whose experience" varied considerably. During the last two years, however, smolts have also been tagged in autumn and release during the following spring. The tags have been almost exclusively of the Carlin type (CARLIN 1955).

Results

The results of salmon stocking in the Baltic Sea have been checked by tagging apart of the releases. In the best tagging groups the return rates have been more than 30 per cent and • the catch per 1 000 released smolts has exceeded 1 300 kg (Table 1). In the Bothnian Bay (ICES sub-division 31) the release results have been improving since 1969. The best average • resultobtained for the 1973 releases - a catch of almost 800 kg per 1 000 - and the best group tagged in 1973 gave more than 1 350 kg per 1 000 releases (Fig. 1). However, since 1974 the results have again deteriorated. In this figure a clear descending trend can be distinguished. But it should be observed that at least the results for the releases in 1979 and 1980 are not yet complete because further tag recoveries may be expected during the next five years or more. The trend of the recapture rate of tagged salmon corresponds fairly weIl to the curve of the , tagging results in kilos. The good smolt year classes 1972 and 1973 mayaIso be seen in the catch of salmon in the whole • Baltic Sea (Fig. 1) . During the calander year of their release in the Bothnian Bay area (ICES 31), the salmon migrate southwards along either the Finnishor the Swedish coast, and a small proportion of the fish have been caught in the Baltic Sea proper (Fig. 2a). During the second summer and autumn most of the recoveries have been made in the Baltic Sea proper. However, it is possible to observe migration of grilse the horne rivers in the Bothnian Bay area (Fig. 2c). During the second winter the majority of recaptures 4

have been obtained from the southern part of the Baltic Sea (Fig. 2d). Age group A2+ can be seen to freguent the coast of the Bothnian Bay,especially those rectangles where they have been released, but recaptures have also obtained from the Baltic Sea proper (Fig. 2e). During thethird winter and spring the fish are mainly found in the Baltic Sea proper. However, there is some aggregation ofrecoveries in the Bothn~an 'Sea area, which might indicate spawning migration towards the north (Fig. 2f). During the'third summer and autumn the spawners of age group A3+ show recovery aggregates in the Bothnian Bay area (Fig. 2g).

In the Gulf of Finland salmon smolts have been released at the

I mouth of the River Kymi. Duringthe second summer and autumn most of the recaptures (gri"i~e)have been obtained from the same . ~.' .- rectangle in which the rive~.mouth. is situated (Fig. 3c), though some recoveries were bbtaincd from' the Baltic Sea prop~r. The majority of the catches:of fish in the age group A2+ were' ., t {. • also made in this same rectangle(49.H6) (Fig. 3e).

In the Bothnian Sea area rele~ses have been made using four different salmon stocks (rivers Iijoki, Angermanälv, Dalälv and Neva). The migration pattern of the released salmon is similar to that of the Bothnian Bay releases, but the River Neva stock does not seem to migrate so far south in the Baltic Sea as the other stocks. However, salmon stocking is so new in this area that it is not yet possible toobtain as clear migration patterns , as in the Bothnian Bay or Gulf of Finland areas.

If we scrutinize the recovery rates in the different leES sub­ divisions (Fig. 4), we observe that sub~division 31 has yielded • 27 % of all the recoveries made after the ca~ender year of the release. All these fish have been on spawning migration to the place of release. In the'm~irt basin ares, sub-division 28 seems to be the most impbrtarit' for the high-sea fishery. ~: .~

. .' . If we look at these tagging;experiments from the point of view of sea ranching and calcutate hbw big apart of the fish released in a certain area return tö··this area, we .observe that in the 5

Bothnian Bay (ICES 31) more than one fifth of all the recoveries made after the calendar year of release in rectangles 60 H4, 60 H5, 59 H5, 58 H5 and 58 H4 were reported from the rectangle in which the release was made (Fig. 5). In the Bothnian Sea area (ICES 30, rectangle 52 H1) the corresponding value was 12.5 % of all recoveries (after releasing year). In the Archipelago Sea (ICES 29) the value was 2.4 %. The highest value was recorded for the Gulf of Finland releases in rectangle 49 H6, where the recovery percentage was 65.6 (Fig. 5).

The most important gear for catching salmon is the drift net and long line, and., in the coastal fishery, the trapnet. The drift net is seen to have given the best catches in sub-divisions 24, 26, 27, 28, 29 and 30 (Table 2). In the Bothnian Bay area the trapnet took 71 % of all the tagged salmon recaptured in • that sub-division. • Discussion The tagging results in the Bothnian Bay area show a clear ascending trend till the year 1974, after which the trend is reversed. In 1972 and 1973 the spring were warm in Finland and this might be one reason for the good smolt year classes. LUNDIN (1977) observed a similar trend in Swedish salmon-tagging experiments. Favourable conditions during the smolt run diminished the mortality of smolts in the sea. GUDJONSSON (1978) reported that when drifting ice off the coas of Iceland cooled down the sea during the smolt run, the smolt year classes 1965, 1967 , and 1968 gave poor catches. When the smolts entered the cold sea, they found. little to feed on and this resulted in high mortality. In Finland the early summer was warmer in 1972 and • 1973 than later in the 1970s. Stocking with sea trout smolts in those years has clearly given good results (IKONEN & AUVINEN 1982).

Since the late 1970s there have been discussions about restricting salmon fishing in the Baltic Sea. This may have made fishermen less eager to collect and report fish tags, and this might be one reason for the poor tagging results on the late 1970s, because the salmon catch in the Baltic Sea does not show the same trend as the tagging results. However, the good smolt year class 1972 6

and 1973 are clearly refledted in the Baltic Salmon catch in 1973 - 1976.

Migration pattern of salmon originating from the Bothnian Bay area differs from that of the Neva stock salmon, which were mainly released in the Gulf of Finland. with the Bothnian Bay Bay salmon, about 40 % of the recoveries made after the calendar. year of tagging have been obtained from the Gulf of Bothnia. With the Gulf of Finlandreleases, where only River Neva stock has been used, about 80 % of, the recoveries have been made in . the area of the Gulf of Finland. In 1964, tagged smolts originating from the Bothnian Bay area were released in the mouth of the River Kymi in the Gulf of Finland (TOIVONEN 1979). Most of these salmon, 67 %, were subsequently caught in the southern Baltic Sea. According to these experiments, River Neva I • stock seems to be more stationary than the stocks in the Bothnian Bayarea. Migratory whitefish (Coregonus lavaretus s.str. L.) from the Bothnian Bay area migrate further than River Kymi stock • in the Gulf of Finlann.(IKONEN 1980). LARSSON et al. (1980) have ebserved that the migration pattern of Bothnian Bay salmen (River Ljusman) does not differ from that of the Bothnian Sea stock (River Skellefte) during feeding migration in the Baltic Sea proper. The present tagging experiments indicate that Bothnian Bay salmon do not migrate into the Gulf of Finland. A similar observation has been made by HALME (194).

SAUNDERS (1977) has suggested that every Atlantic salmon stock , has its own migration pattern in the sea. In the Baltic Sea a great nurnber of tagged Finnish salmon have been caught in sub­ division 28, north and east of the island Gotland. LARSSON' , et al. (1980) have also reported that the chief areas in which tagged salmon are caught lie around Gotland.

The salmon stocks in the rivers of the Bothnian Bay area migrate long distances, with the present state of the Baltic Sea fishery, these stocks are not very suitable for sea ranching purposes, because so small a part returns to the releasing place. 7

The reason for this is heavy high-sea and coastal fishery. In the Bothnian Sea area, the original stock, the salmon of the River Kokemäenjoki has been destroyed, and stocking has been done with salmon smolts originating from the Iijoki (ICES 31) and the River Neva (ICES 32). According to preliminary tagging results, the River Neva stock has given a much larger number of recoveries in the Bothnian Sea area than the Iijoki smolte, the majority of which have been recovered in the Baltic proper.

In the Gulf of Finland, salmon originating from the river Neva have been used for stocking purposes since 1976. This salmon stock does not seem to travel far, because more than 80 % of the recoveries have been made in the area of Gulf of Finland According to tagging experiments with spawners in 1903 - 1913 r • the original salmon stock of the River Kymi did not migrate very far, either (JÄRVI 1931). The original salmon stock from the; Kymi has been lost, but the River Neva stock has a similar migration pattern and thus seems to be very suitable for stocking purposes in the Gulf of Finland. This stock is also suitable for sea ranching purposes, at least in the Gulf of Finland. The fairly high recapture percentage in the rectangle of the releasing place also reveals also that the fishing pressure in the Gulf of Finland is not high. For this reason sea ranching of salmon in the Gulf of Finland still seems to be profitable.

Good srnolt year classes in 1972 and 1973 raised the catch of , salmon in the Baltic Sea to a high level (about 3 000 t) in 1974 - 1976. The favourable weather conditions in 1980 - 1981 have probably also given rise to good smolt year classes, • which will be reflected in the catch in 1982 - 1984. 8

References

CARLIN, B. 1955: Märkning av utvandrinsfärdiga laxungar i Lagen. - Vandringsfiskutredningsmedd. 1955: 15.

CHRISTENSEN, O. and JOHANSSON, N. (Ed.) 1975: Reference Report on Baltic Salmon with additional information on Baltic Sea trout compiled by the Working Group on Baltic Salmon. - Laxforskningsinstitutets Meddelande 2/1975.

CHRISTENSEN, O. and LARSSON, P-O. 1979 (Ed.): Review of Baltic Salmon Research. A synopsis compiled by the Baltic Salmon Working Group. ~- Cooperative Research Report 89/ICES~

GUDJONSSON, T. 1978: The Atlantic salmon in Iceland . • - Isl. Landbun~ J. Agr. Res. Icel. 1978 10, 2:11-39. HALME, E. 1964. Report onsalmon tagged in Finland in 1959 ­ 1964. - ICES, C.M. 1964, No 61. • HILDEN, M., HUDD, R. and LEHTONEN, H. 1981: Miljöförändringarnas inverkan pä fiske och fiskebeständ pä den finska sidan av Botniska Viken och i Skärgärdshavet. Mimeo. - Finnish Game and Fisheries Research Institute, Helsin­ ki. 14 pp.

HURME, S. 1962: Suomen Itämerenpuoleiset vaelluskalajoet. ­ Maataloushallituksen kalataloudellinen tutkimustoimisto. Monist. julk. vol. 9, pp. 1-55. , IKONEN, E. 1980: Migration of river spawning whitefish in the Gulf of Finland. - ICES C.M. 1980/M:13.

IKONEN, E. and AUVINEN, H. 1982: Results of Finnish stocking with • sea trout (Salmo trutta m. trutta) in the Baltic Sea in 1971 - 1980. - ICES C.M. 1982/M:39. JÄRVI, T.H. 1931: Merkityt lohet. - Suomen kalastuslehti 38. r

I 9

LARSSON, P.-O., FJÄLLING, A., GRÖNLUND, M., JOHANSSON, S. and NATHANSSON, J.-E. 1~80: Undersökning av tva laxstammarnas uppehällsplatser i östersjön. Grupparbete vid Fiske­ vardslinjen, Göteborgs Universitet. - Laxforsknings­ institutet, Information 3/1980.

LEHTONEN, H. and HILDEN, M. 1980: The influence of pollution on fisheries and fish stocks in the Finnish par~ of' the Gulf of Finland. -Finnish Marine Research, vol. 247, pp. 110 - 123.

LUNDIN, H.-E. 1977: Sammanställning över märkningsförsök pa laxungar. TabeIl F. - Laxforskningsinstitutet, Information 1/1977.

MÄKINEN, K. 1972: Jokien rakentamisen vaikutus vaeltavien lohi­ kalojen poikastuotantoon Suomessa. Mimeo. - Institute I • of Zoology, University of Helsinki. Helsinki. 98 pp. SAUNDERS, R.L. 1977: Sea ranching - a promising way to enhance pöpulation of Atlantic salmon for angling and commerclal • fisheries, - Int. Atl. Salmon Found. Spec. Publ. 7:17-24 SJÖBLOM, V., TUUNAINEN, P., TOIVONEN, J., WESTMAN, K., SUMARI, 0., SIMOLA, O. and SALOJÄRVI,K. 1974: Itämeren ja Belttien ka­ lastusta ja elollisten luonnonvarojen säilyttämistä koskevan yleissopimuksen perusteella Suomen bsalle tule­ va lohenistutusvelvollisuus. - Riista- ja kalatalouden tutkimuslaitos, kalantutkimusosasto. Tiedonantoja, vol. 2, 22-52. , TOIVONEN, J. and IKONEN, E. 1978: Havsöringen i Finland. - Fiskeritidskrift för Finland, vol. 5, pp. 104-109.

TUUNAINEN, P., NYLANDER, E., ALAPASSI, T. and AIKIO, V. 1979: • Kalastus ja kalakannat Tornionjoen vesistössä. Mimeo. - Finnish Game and Fisheries Research Institute, Helsinki, 82 pp.

TUUNAINEN, P., IKONEN, E. and AUVINEN, H. 1980: Lampreyand lamprey fisheries in Finland. - Can. J. Fish. Aquat. Sci. vol. 37, pp. 1953-1959. ­e kg/1 000 released • Baltic salmon catch t 3 000 0-0 best resul t 6.--Ij. mea n .-. paarest 2 000 result

1 000

1 000

1970 71 72 73 74 75 76 77 78 79 80 recapture %

30 500

20

1969 70 71 72 73 74 75 76 77 78 79 80 1969 70 71 72 73 74 75 76 77 78 79 8 ...... o Figure 1. Results of stocking with tagged salmon. Recoveries in kilos/1 000 fish released, recapture percentage and total salmon catch in the Baltic sea. 11 , 10" 11' 14' 16' 18' 10' 22' 14' 16' 111' 30' , 10" 11' 14' 16' 18' 10' 22' 24' 26' 28' 30' ~, 66 'a. 60 r r-;- "-, 60 , '( 59 59 65 , ~ , 1-10 ree, .~ 65 'J, (, •• 58 ...~ 11-40 ree. ( .- 58 ). I~ • • 57 57 64 41-80 ree, , .j. 'l · ,,{' . . 64 • 56 ".( ) . 56 • 81-150 ree , 55 55 · > 150 It-": · . · 63 ',. · 54 · 54 ' · , , • " 53 53 62 62 ~" · (. .\ 52 · , 52 ( , · . " 51 , / 51 61 · ~ · 61 · · ·. .t ---LI SO .l ---LI' 50 ';;1 ~II')...... , 49 ~:>. ~T\....- 49 60 · 1? , 't, • ];1 · V~ 60 l....i I 48 , T J I V ~ 4 8 · r -=' 47 -=' '?F-~ .C". ,:. '5" ,er 47 59 · ]. 59 IV 46 '6> 'V j. 46 >--f- "t.] 45 ~ , "" V "'11 '\ "" )/" 45 , 58, [...".. · '11 • 44 , 44 >-- - · f-- f- :lf ~/ 43 ,~} · 43 57 ~-.I · . /"d' 57 h l/' /"dJ · ""\ /, 41,' ~. J: '\ I/I , 42 .-r---' I 41 'r---'V 41 56 PJ~ ( 56 ~ ( , · ~:ß • 40 ~ß ) 40 I<..... ;r ' 39 I<..... '''r ·4j 39 55 .. Al 55 ~ ~ I~ v~9!;' 38 ~ ~:r'1 'J..--~ /;- 38 a 37 ~ b 37 54" J~ ~v 54, l~ 'L-- 36 ~ 36 • f9 GO GI G1 G3 G4 G5 G6 G7 G8 G9 HO HI H2 H3 H4 H5 H6 H7 H8 H9 J 0 f9 GO GI G2 G3 G4 G5 G6 G7 G8 G9 HO Hl H2 H3 H4 H5 H6 H7 H8 H9 J 0

, 10" 11' 14' 16" 18' 10' 16' 18' 30' .66 , 10' 12' 14' 18'16' 20' 22' 74' 26' :ci 60 r-- ••• " 60 , , 59 r 65 ... , -( 59 65 'J. . . 'I~·1- 58 ( r 58 , ). 57 I, J 57 64 "J ~ fj. 56 , · /' 56 , , • ':j. 55 , ',., , (. 55 \J, , , 63 54 , , ~4 , , 53 62 r .1' . 53 ' '~ , 62 52 ·• ~ (' .. 52 , ( 51 · 61 .. , 51 )". 61 t· ' .t 50 ; • ~ · ·• • .Li 50 , ~ '( , 1';;1 .~I~ 49 ~ · 60 , ,... ~TI~ ,.9 , ,, 60 lit / ' • LI I V"" 4 8 / . • , 1-1 I ~ .... 48 ..')ct. r -=' 47 ~ 59 '~F-r,. 'j" r 47 • • ,· 59 ?F"-~ -cA ," j. 46 • , , ·, , _/. · . ,~ 46 r~ • • • .~/ ->-I~ , 1 • "'l'l 45 , <> 1 . )/ , -: •• • 56 • •• ':tI t1~ ~ r. •• :~tH 44 .....: H~- • •• 44 • •l/ 43 b'~ , ·~CF 43 57 '~.J: \ • • 57 • • I.• 42, · '.J: '\ :// 47 . •• •, •.1. • .i 41 41 ':ß~V~ · ·, • 56 R •. ' • •• f' . . 40 ~''''') · · · • :-j5 (e •• • 40 • :11<"'" Tl r.t_ 39 1"---1, • r.l•• , · •• • • • • lJ 55 • 39 . h;J~ ')1 , •• • , 38 bi ~~ 38 :~ · 37 •, !-~•• · 54 ~V e 54 [rV~ d 37 · 36 · ~ 3ö ~ f9 GO GI G1 G3 G4 G5 G6 G7 G8 G9 HO Hl H1 fl3 H4 H5 H6 H7 H8 H9 JO f9 GO GI G7 G3 G4 G5 G6 G7 G8 G9 HO HI H2 H3 H4 hS H6 H7 H8 H9 JO

Figure 2 . 'rag reeoveries of salmon released in the Bothnian Bay (sub-div. 31 ) in 1969-1980, a = stoeking year (May - Dee) b = first' wihter (Jan - Mar) e = seeond summer and autumn (June' - Dee) d= seeond winter (Jan - May) 12 10' 12' 14' 16' IS' 20' 22' 24' 2&' 28' 30' , 10' 12' 14' 16' 18' 20' 22' 24' 26' 28' 3e' 66 66 ~r~ 60 ,f'T"- i'-,. 60 , «., 59 } 59 65 , 1-10 65, f' (. , I·~ 58 11-40 ( 58 • ) • .J', Ir , 41-80 57 I ~ 57 . 64 , • ... 56 /" 56 81-150 , J , ,. , 55 , 63 • • • . 55 63 · > 150 ' , , 54 '" 54 . ;, · 53 , , ., 53 , 62 ·, 62 r '. , il 52 '/> 'I~ 52 (.· ·, , , , 5 , ( , 51 61 · , 61 • · ...:. · • ....LI 5o · , ' 50 ~ , . ~ , , , , f""'i II 'I---- , .];1 .~ 49 60 60. t." / ", 11 I ~ 4S ' .J. . \'J'"' I 1'11 ~~ 4 a IL~~ , · .r .....", 47 r --=' 47 59'V'F-?' , • , 59, ;?'~~ t ~ , ,~ 46 ./ • . - ~ ,~ 46 , ";;1 SI ' ' 45 - ~ , 56 .. >I'" ':n , >r '-TI 45 56 . W . Ä 44 , - ~ • ~GI '-7' -- 'r 44 JZ.r •' 1 43 t~ 43 57 '. 57.2.5 v , /'df ~'l • , • EI cl. \ • 42. ~o:t \ It 42 , • • • ·, 41 56 ~ • ,'V · 41 , ~:>~) (.. , , •, • , 56 , · :5 ·", 40 ~:ß ~ f" , 40 , · , hs"'·.' 39 ·, ~I 55 'V 55 r--..rT '(. 39 )) ~J:> · {:~br· , · · ••• L-- 38 ~ Pr I,' . 1--- ~~br 38 , e 37 37 54 !~k'rJ-- 54. ~ ~J-- 36 ~ 35 • F9 GO GI G2 G3 GI, G5 G6 G7 G6 G9 HO HI H2 H3 H4 115 H6 H7 HO H9 J 0 F9 GO GI G2 G3 GI, G5 G6 G7 G6 G9 HO HI H2 H3 H4 H5 H6 H7 H6 H9 J 0

, 10' 12' 14' 16' 18' 20' 22' 24' 26' 28' 30' e6 10' 12' 14" 16' 18' 20' 22' 24' 26' 28', 30' ''f'. 66. i'-;-~ 60 ".~ r"rot-. . so , ,j, 59 ~ 65 , 59 ,C, 65 I Jt 56 ..." (, ,. 58 I ~ 57 64 I J, 57 · ,:' , 64. 56 · ,..( 56 , / 55 · , ' t"1J 55 · \" · , 63 r 54 ~, , · . 53 62 53 · · 62 · 1 ,!; 52 > · , ~ ',.I 52 , , 61 I' 51 , , , 6\ L 51 Il 50 · .L1 .t Li 50 60 'l,' ,.X I I 'h 49 ~;> '];1 1,9 · · 60 't, ,..ri, II 'I---- /' 1.1 I ~ ~ 46 ~~ "-.::;J' I I 111 43 ;?F-~ •. ")'" r 47 "==' 59 'b>-F-~ ")" r '1 -,/ ~ ,~ 46 _/ , ~ ,~ 46 f-f- , L~ 45 ~ · )1'" _YI , 45 , . ~ · 58 · · v .\:1 w 44 '-- 1.-7" '{ . 44 V, 11 ~tiI 43 r- J2J " · 57 ~ ,rZJ ~Cb' 43 . .{ JII , , 57 · , ::1 · 42 " ~'~r-~ I. 42 41 ~rl ~~J f' r--'l 56 41 40 , f . ~ 4(\ .:ß "'-,.?T " . · f) '~Pt , , · 55 39 r ' rJ 39 )1 '21 l", '. l---'-t ' 55, -J~{l , • 38 l---~o/ 30 ~~~!;1l--- J 7 0/ g 54, ~~~,

e third summer and auturnn (June - Dec) f = th;i.rd ,winter (Jan - May). g = fourth surruner and auturnn (June - Dec) h = l'ater recoveries 13

10' 12' ". 16' 18' 20' 22' 2" 26' 26' 3;)' 10' 12' '" 16° 18' 20' 22' 2" 26' 26' 30' 66' 66 r"r-~ 60 · .f'r-r-.... 60 f" 59 '( 59 65 n 65 Jl . c · 1-10 Ir 58 · ( r _6 ) ) ·11-40 I 57 J 5 64 · > 150 /' f 56 · /' f 56 • ~ 5 , ~ 5 63 ~ · ," 5, '" 5 53 , 53 82 > 62 > · ~ 52 ~ 5 5 , { 5 61 61 · ...A 50 • 50 " 'l, ,~ ~ · .. ·1'"·1·' ~ 49 "\.., ~ ~ .~ 49 60 60 ~ ~~ 4 6 · / ,,1...1.1 46 · / 111 ~ • .T --=r rs- --.;;;' 4 47 J' 7 =-(1 'J> 59 59';?- •V'" =- /l> -,/ 1'\./ j. 46 _/ I',t: j. 46 .-~ ~ 45 ~ ),/ '<'7 45 1 ir 'Tl 58 56 ,, 44 . ~. ~ /i ~ c- Ii ~tJJ l~tJJ 43 .~f J ·1 43 ,lts v 57 57 ~ .J: "- I1I 42 .. ~'\ I, 42 ... ,...... ·1 4\ .-. 41 56 ~ 56 ~ '0 :'~ ). .40 1 • 9 ...... ,r [) 39 I<...... r r [) 55>i5 55 )l (:jJ ,""- ---~~ 38 ~ ~ ...... ~~ 36 37 .,~ b 37 ,~ ~t- a 5,,

10' 12' 16' 18' 20' 22' 24' 26' 26' 30' 10' 12' 16' 18' 20' 22' 24' 26' 28' :;0' 66' ". , • r- 66 1'" "-.. 60 t' r--j'-,. 60 '( 59 59 65 11 , '( Jl · p~ 65 < 58 ( r 56 I / 57 ) · 64 /' f 56 · ,)-' 56 f / ,. ~ 55 ~ 55 63 SJ. · " . ) 53 53 62' > 62 I) ~ \ 52 · ~ 5 ( . 51 , { I) 5 61' · 61 · .l 50 • .l ..cf so .' \.., ~ , 1)11 49 \., ~ ~ .~I·I~ I,3 60' , , , :r~ 60 / 46 / 111 ~ ~ 4a "--=:7 )'" rs- 47 ~ . ""'= 4 59' V'" 0- () · 0-(1 -,/ . IVJ 46 ;?' -,/ 'V ~~ 46 , ~ ~ ~ )r '5 -:g ~r 'TI 45 1 '<'7 56 44 ,4 ~ 4' ~. ,. f-- /i' · r-/i vo 1~ti1 43 43 57' t2'r 57.:zr V' /"dJ ~ ..cI //1 . 42 ~ ~- \ I, . 42 ,...... 41 .-.'1 . 41 56 ~)" ( ~ ( 40 ) . 4o ,"-, l"T . . .. iJ 39 ~ß "-, rr . . :j 39 55.i5 , 55 :;;J ~1 1",,- I.--~~,.. 36 ~ PT L I.--~o/ 36 37 37 $~ C 54 LrY~ 'v d -· ~- 36 36 kr F9 GO GI G2 G3 G4 G5 G6 G7 G6 G9 HO HI H2 H3 H' H5 H6 H7 H6 H9 JO F9 GO GI G1 G3 G4 G5 G6 G7 Ge G9 HO HI H2 H3 H4 H5 H6 H7 H6 H9 J 0

Figure 3. Tag recoveries of salmon released in the Gulf of Finland (sub-div. 32) in 1976 - 1980. a = stocking year (~ay - Dec) b first winter (Jan - May) c = second summer and autumn (June - Dec) d = second winter (Jan May) 14

, 10' 12' 14' 16' 18' 20' 22' 24' 26' 28' 30' 66 , 10' 12' 14' 16' 18' 20' 22' 24' 26' 28' :;0' t- 66 :t' 60 :rt-i'-- 60 , ~ 59 65 "'"Jl , 59 1-1,0 ,-'\) 65 f Jl 58 .11-40 < Ir 58 I ) . J 57 , / 57 ./ 64 f 56 r J 56 " , ~ 55 , ~ 55 v 63 54 54 , 53 , ( 53 62 , > 152 r 52 '~ 52 ( 51 61 , , I 51 ),. 61 50 --11' j50 ~ .~ , ~'"f~ 49 ]) 1,9 60 60 t ,..,...--r·1 T't.--.. . Lli ~..., 4 8 48 '"' / 1..1 I V..., '-=>' '" ~ ."J' r 47 r 47 59'?F-~ 59'b>-F-~ ."Y -,/ V ,~ 46 ,./ v ,f--f--~ J 46 , I~ lr ':r1 45 )r ~ 45 58 . 44 . 44 - Vi >-- f-- /r ::;/r V /h.,Cif 43 , [\ ~.J >- , 57,t:2:1 V /'0 r\ 11 42 ~.J: ~ J 42 ~- 41 41 56 ~, , 56 r-- • \ 40 ~~ ) 40 ~:ß f ':8, .J. <...... 7 r ' 39 1<...... 1' 'c IJ 39 .~_ ~r 1",- 55 V-~~ 38 ,~-~' v-~~ 38 , l~ ~L.-- e 37 ,, c.,..v-:~~'1L.-- f 37 36 35 F9 GO GI G2 G3 G4 G5 G6 UI G8 G9 HO Hl H2 H3 H4 115 H6 117 H8 H9 J 0 F9 GO GI G2 (;3 (;4 G5 (;6 (;7 G8 (;9 HO 111 H2 113 H/,115 H6 H7 H8 i19 JO

'e = third summer and auturnn (June - Deo) f = later recoveries , 15

60 59

58

57 56

55

54

53

52 51 50 49 48 47 46 45 44 43 42 . 41 40 39 38 37 36 '--...... I._""'----.L.._L...J.I...... -.J._""'----'-_...... -I--.J._...... -.I._...... --L_.l.-~___II__ __ F9 GO G1 G2 G3 Gt. G5 GE> G7 Ga G9 HO H1 H2 H3 H4 H5 HG H7 Ha H9 JO

ICES 27.3.03.00 (Saltie)

Figure 4. Percentages of tagged salmon recaptured after calendar year of release in different sub-divisions in 1969 ­ 1981. The taggings have mainly been done in sub-division 31. 10· 12" 14" 16" 18" 20" 22" 24" 26" 28" 30"

66" ~ .f -.,.. 60 fl20.8 59 65" er I~ 58 ) 57 64" ,)" 56 ... ;::~ 55 ,.! r I 54 ( 53 62" • ~ 12.5 52 51 61" "lA ~.l 2.4 ~/1 50 ,~> ~\ ,~'17 49 60" 't. . \.-. ~ ...... / 1-1 48 oa::::J ~jt~ ,,_5c 47 59" r ,f "V 1\ --L' } 46 !~ )/rt.- rJ 45 58" 1 ., /( 44 r-- r- I~;- ~ ~/ 43 57" ß ,-11 ~ ~~ \ I/I J 42 v ~~ .~ 41 56" JU~ \ 40 10 ...... r L' )1) 39 ~ ~.~ -_vv-~~,? 38 6~"1~ 37 , 36 F9 GO GI G2 G3 G4 G5 GI) G7 G8 G9 HO HI H2 H3 H4 H5 HG H7 H8 H9 JO

Figure 5. P7rcentage of total tag recoveries reported in the statistical rectangle where the releases have been made. Recoveries in the stocking year ex

Table 1. Results of stocking with tagged salmon smolts in the Gulf of Bothnia, Gulf of Finland and Archipelago sea.

Sub-division 31, Bothnian Bay Sub-division 30, Bothnian Sea stock i ng poorest best mean number of poorest best mean number of year % kg/1000 % kg/1000 % kg/1000 experimental % kg/1000 % kg/1000 % kg/1000 experimental groups groups n n

1969 1970 3.9 137 12.6 481 8.5 323 7 1971 12.2 360 20.5 672 15. 1 493 4 1972 18.6 620 25.2 861 22.6 792 5 1973 13.2 378 33.0 1366 17.0 624 11 1974 5.0 216 14.8 527 :9.2 318 6 1975 3.3 83 28.0 974 11.6 398 11 0.2 28 15.4 647 10.3 415 3 1976 2.7 88 6.4 186 4.7 156 6 1.9 129 13.4 572 5.8 282 3 1977 1.0 20 6. 1 287 3.5 126 18 1978 0.8 24 6.0 238 3. 1 111 11 19791) 0.6 13 4.3 154 2.4 79 14 1.5 42 3.1 104 2.6 79 4 19801) 0.4 2 4.6 61 1.4 19 25 0.4 7 1.6 21 1.0 14 3

1) the results are incomplete ------. e

Table 1. continues

Sub-division 32, Gulf of Finland Sub-division 29, Archipelago Sea stocking poorest best mean number of poorest best mean number of year % kg/1000 % kg/1000 % kg/1000 experimental % kg/1000 % kg/1000 % kg/1000 experimen- groups tal groups n n 1969 1970 1971 1972 1973 1974 1975 1976 4.4 170 4.4 170 4.4 170 1977 0.5 27 6.8 251 2.6 103 3 1978 3.9 112 1 9.2 322 6.2 208 3 1979 ) 1.6 54 7.9 252 3.4 119 4 19801) 1.4 31 7.2 220 3.5 89 8

1) the results are incomplete 19

Table 2. Percentage distribution of catches of tagged salmon by different types of gear in the leES sub-divisions.

Sub- drift other long trapnet others division net nets line

24 56.9 7.2 28.8 7.2 25 45.3 5 48. 1 1.6 26 48.8 4.9 45.2 1.0 27 63.1 4.7 32.0 . 0.2 28 49.5 5.8 43.9 O. 1 0.1 29 51.5 12.6 33.1 1.8 0.9 20 37.6 12.4 25.0 19.2 5.8 31 0.6 18.8 0.3 71.1 9.16 32 9.6 64.3 13.4 10.2 2.47

,