lCES C.M. !99S
CM 1995Jj:2! Ref.B
Dldtic Fish Committec
SALIN1TI!OXYOEN UEGIME
~F
OA1:rnc lJ.HOPER IN 1992-199.5
L~
WA'i'F..R
l~D
TIm SOUTH-EASTmt.'\l"
DEWillRSf..L
FU~H
PA..~.T
OF
LIVING CO:NDITIONS
by
Y.N.Fddman, N.A.N.uurov, A.S.Zczem,
Atiantic
Scie:~1illc.ResearchInstitute
E.S.~zC!'t1
of Mru:ine Fisherl:es Md Oceanogmphy (AtIantNIRO),
5, Dm.Donskoy Str., 'KaUnmgrw, 236030, RussiI1.
•
AßSTRllo.CT
Hydrologienl features of the
south-~~t naHk~
Scaare
prc>;;~nted 011
obtnineu hl 10 G".::.lses cf lUV tcMcHCC.ri8tt.~iu from Iv!üy 1992
lo
the bnsls of materlalIJ,
Mny 1995. ~iaj9t' trends in
'.
.
for a.he Iatest 15
1993,
we~c
yC&m
inHow cf
ime]ysed. Cod
Ks.ueg~lc Wö1.tCl· Üll Ju;:m~J'
spaw;'llr~g condHio1l3 Cl"C chu..~Ledzed
.
..
,.-.
fcr 1992"1995. The resultg
ar boaom trawl smveys In Ivlci:ch-AprJ 1993-1995 cllew to detlne
r..
..
~e8Xu..-es m
.
SPi"h"lg
r
.
. , t ••
J' ••
lor
vnno~ üyuro~OgH;~ OOnlm.1Oil!Z.
,
and weaker one in DC".., emha·
HU!jOI"
rod dLstrHmtion
."
"
•
- 2 -
INTRODUCTION
-
In 1992-1995 AtlantIURO reoearcheo on R!V lIj\tonocr;}rstall tl revealed
signifieunt chainges
of hydro.logieaJ. oondi tions in the SouthEastern Raltie Seat espocially withi~.the deep-water and nearbottom layers .. Taking.in aceount seale andamplitude of h:Ydrochomieal indices variability observed in 199)-1994 as a result of adveetion
(January, December of.1993),
latter may be considcred as tho
most important event for the last,2 deeadea.
In '. the paper presantad tho att empt is made both to revoal wa ter
condition variability on the basis of absol~te valuoD of hydrologienl' fea.turos in the Douth-Eastern Bal'eie S~ai and ~o aSSQSO "
quantitatively spatial and temporal scale of udvoetion nnd its
tlbnsequences for cod living conditiona within ~ubaroa 26 of the
Baltie Seu~
~~TßRIA1
AND METHODS
Analysis of hydrological conditions and temporal variability was
carried out onthe bnsis of materials of 10' R/V "Monocrystall"
eruises in Subarea 26, restricted westwards by economical zones
of Pol8,nd and Sweden, d1..lring March-June und OctobeH>-·November 19921995. '
H,y-drological resear'Jhes were performed with a. probe STD'-1000 from
thc. surface 'to the bottorn with temperature and
oalinity date.
.
printing at every 5-10 m und in near-bottom layor. ~otully over
hydrological stations were carried out in the area during the
above period. At standurd station Cl cornplex of hydroehem:i.cal
.
measurements was performed. Sampling waD made by Uansen's bathometers,. dissoly~d oxygen eontent io est~mal:;ed wibh Vinkler's'
method (over 500 measurements). Temporal hydrologlcal variability.
~as defined on the basis of observations
2 decpwater internationa.lstations: P-1 in the center of Gdcnsk Deep and BY9 - in
the Southern Gotland Deep.·(Fig. 1).
•
eO
,
,
at
Data on cod dist~ibution in the south-eastern part of Subarea lCES
26 in the BaltieSea are presented baaed on the results of 114
eontrol hauls with bottom trawls DT/TM 30/30 and DT 2S.5i37.6
with vertical .opening about 8 m and small-meshframe in thc cod-
end with u' bar length of 6.5-10 mm.
- 3 -
•
Trawling was carried out for 30 minutes. In total 10 948 specimen
'of cod wero analysed and measured. Maps of distribution oVer the,
traw1ing survey area for 1993-1995 were drawn up on the basis of
eod eateh size and composition.
RESULTS
AND
DISCUSSIOll
During the last years hydrologiea1 conditions' of the S'outh-Eastern'
Bn1tie Sen waoeharncterized by signifieant variations, stipulated
by o.dvection processes predominance in formation of \'Iater co1urnn '
vertica1 ,structuro. Thus, whi10 during 1992 and ear1y '1993 definite
trends of sa1inity decrease in near-bottom 'layer and at middle
depth of, Gdansk und Gotland Deeps, und within a broad are~ of Gotland
,Deep u~ exclusively long-term staßn~~ion period was'observed,
~
.'
~durinß ~urch-April 1993 a considcrablc increaso of salinity was' ,
found in GdanskDeep. (Zezera,
1993). Therefore, inflow
ofKattegat~
.
.
water, observcd in tho straits area in, January1993 (Anon~ 1994),
reached the So~th-Eastern Bultic Seu by Aprilwhich rosulted in
above-mentioned, chainges of hydrol,ogical condi tions._ .Dato. from
theTable 1 allows to assess tllat process scale bothin absolute
value und' inthe average long-term valuos. 'The ,Tuble' shows that
'absolut~ ~ncrease of salinity in noar-bottom layer ~xceeded '~~o
in Mareh-May 1993 while negative anomalies deereused by above 10
times. '
-"
In general adveetion of highly saline water of the South-East
Ealtie Seu in 1993 was characterized by restricted und ahort-term
impact to Gotland Deep as compa:""ed to Gdansk Deep. In thecontral
.part of thelatter wi th L.. decrease of disso~ved oxyeon .from 0.7 to"
0.2. ml/l was observed first in the horisont of 200 TIl from July to
October while tho.t in noo.r-bottom 1ayer decreased from 0.2 to 0.5ml/l
und by fall hydrogen sulfide apeared iXl thc near-bottom laycr. As
referrjd to the extrem'~ soutli of Gotland Deep (north-western part
ofSubaren 26, otation BY 9 where no stagnation was,observed earlier).,
on1y insignificant i'ncre::1.SO ofoalinity (0. 3-0. 51~) in near-bo ttom
layer (100 m ~nd more) was found.
Maximum advection proeesses develppment conce~ning impa~t upon
wa.ter conditions in the arsa, was observod,in spring 1994, though
the next Kattegate water inflow (Deeember 1993) was considerably
wenker in salinity' alld volume (45 cub. km vorsus 135 cub .. km)(Anon,1994)
'I
•
- 4l!owever, taking in account the. "truce" of the previous .advection,
increase cf absolute salinity values fromsP~ing'1993 to sp~i~g'
1994 ~mounted to 1.0-2.5700 in .the ~ayer_c.f'.70ß:·.b6ttom of Gda~~k,'
Deops and O,.9-1.4~~o in tho'layer'of 100m:-bo.~tom.. ot,~söuthernGotland/
Deep" For the first time during the last years salinity value in
the near-bottom layer exceeded 1J%0 in GdanskDeep und, 12%oiri
Gotlund Deep. In the, first 'cascavorage ,\*teightod salinity over
'the total vlator column wäs equalto, average long-.term value while
in near':'b'ottom layer the. lattor, wa~ ~exceeded by 0.8%0 <see [fable 1).
,
,
•
The major consequellce oftransformed Kattegate water advection'
in spring 1994 was a total replacomont of deep w~ter in the
EastcJ:'l1 BaI tic Se~. In the vast area the rnoot long-te:rmstagnation
period in the current centure (over 15 yoars )\'m.c completed.
Dissolvec1. oxygen 'level in the near-bottom 'layer of Gdo.nsk and
Central Gotland Deops exceeded3 rollI at sat~~ation of above 35~.
Such high'values had been 'observed in the area tor the first
time since1930 (Auon, 1994).
'.!,
Variations of salinity
' .in near-bottom layer of Gdansk Deep and
extreme
south of Gotlo.nd Deepduring 1992-1994 are, p-t-'esented iLl
,
Pig. 2.
'
An a
of considerable salinity increa.se in the deep water
durin~ 1994, the lligher stratification of water colur:m occured,
especially that in Gdansk Doep und northwal'ds where vcrtical
gradients of salinity a.pproached O.32-0.53~o per 1 m in individual
areas. IncreanG of gradient in tho halocline stipulated consideruble decrease of oXJ~ßcn level in near-bottom layers of d?ep-water
urea from sum:ner to fall of' 1994 as compo.red to 1993. 't.['herliHore
in October
1994the level of dissolved.oxygen .amounted to 0.1- '
.
, 0.7 inlll (saturation belo\*! 8%)' 'in ,near-bottom"layer, as comp'ured
to 1.0 -1.7 rollI (18% ) last year (Fig. 3). ~huat one of the most
important consequences ofadvection
1993-1994 was occurence of
conditions for development of anoxie eonditionzone in Gdunsk
Deep during' winter, 1994/1995. As is'sh~\'"n by the ·observa.tions in'
Wo.rch 1995, in the area with depth of 80-85 ro southwards of 56 c u,
the s~rt-term development of the abo~e-mentioned zones, similar
to. those in winter 1993-1994, was found in couple with retention·
ofthe lutter till spring, which also, 1s cuus ed by lower winter
. coöling of surfuce water and decrearie of winter
. eonvection depth
resu~t
,
'
tt
' .
,
,
in
'
,
.
.
'
-""5· -
.s comparcd to thc previous period.
j~hus, hydrol'~ßical
conditions in spring 1995 were characterized
hy cxistencc of zon~s'with oxiSEm dei'iciency (O.1~O.7 ml/l
?elative saturation below 8~) oVar the vast ~reacl.~~UBpvkllih~\u·
be~ d:Eerved:1.'1 spr1rJ€; fol'
first tim~ since 19:E.:in late ftl8if~y J~e ·:futher
decrcasc of oxygcn was 'observed also in ~he, central.Gotland Dcep
where oxygen level vies :. below 1, rol/I in the neo.r-bott~m layer•.
Analysis of near-bottorn ternperature and salini ty' variabili.ty, trom
late March to June 1995 revealed intlow of arlOther parecl of "fresh"
. North '.Sea \'mter, intotho urea. which. resulted
in
,
.'. .
. noar-bottom03a.li.
nity increuse and oxygen level improvement in Southern Gotland and
Gdansk Deeps (oxygen'level,wasover2 ~l)l at ~elative content
. o f 25-)3/;). However,in the Centtal Gotland Deal> and nor~hml~ds'
of Gdansk Deeptho'conditions persisted to incrcase oxygen deticiency inthe water column below halocline und .in near-bottom
lcYers.
.
at
ihe'
,
,
As compared "GO spri.ng observations of 1994, and in spite of advec,tion oboer~c~, snlinity ~alues 1n Gdansk Deei~ere lower than those
of the previous yeo.r by O.8-1.1~:~o in the,near-bottom layer'and
, by.2.J-J.O%o in the layerof 65-85 m.,As comparcd to long-term
'average values for the whole aren, negative salinity anon~lies
occured in ' ,1995,)'"as \vell aS in 1992 and· 1993 (:Jee' Tfible1) ~
Cornparison of I..Ial"'ch and uruJr 1995suI'veys results allo\"led' to mako "
conclusion on the dominating advection water flo~v tO\;lD.l'ds ,Gotland
Deep which by' the erid of fl"Iay was clearly tre.ced in thc v~rt i'cal
efield of temp.erature, $a.li~.ity and oxygen up' to 56°50'N, i.c.
.
,by JUly oX'Jgen cond.:tions may be,expected to improve end aalinity
of deep water to ~ncreBse in thc central part of thc araa.
Observ~tions made in Gddnsk Docp, including standard stations
dublication in t~rch, May'andJune, showed the oposite situa~ion,
decl'oa.sc of advec'ti.on in' that direct'ion which suppose no irnprovement of conditions ,in the urea northwards of.theDeep.
'General c1ynamico of tempo'ral -cemperature, salinity,and oX,:vgen
val'iability at·otationu P-1 and BY9from 1992 to 1995'io· presented'
a.t Figuren 4, 5.,
"
Naturally, such sherp variations, of hydr'ological, conditions ' affected conoidero.bly the livine conditions of dcmersal fL.3hes,ün:i
'1xygen deficiency obucrved
winter 1994/1995 in thc deep le.YCl'
in
,
.
- 6 -,
ot
Gdansk Deep affectcd thc Daltic herring und sprat wintering
condi tions. Tho impact on the BaItic cod :Ls repre~ente'd. b;r considerablo variubility of ~pawning grounds'area.
Ilocation of isohaline 10~~0 in spring (Antonov, :1987) may bc conoidered as an indirect evidence" of advectlve pracessas strength
anel spawning grounds aren varia'bility. Assessment of the area' ."
of near-bottom wator ~ith salinity above 10%0 showed considcrnbl~'
variations of the latter from 1992 ~o 1995.
,
,
~,
,
,
Minimum areaof saline wnter was observed in 1992 und in Iibrch
1993. During 1993':'1994 when Kattegate'water inflaw approached
maximum, the aren ofoaline', water was thc most ane,' however' in
the first, half of 1995 the' urea decrcased due 'to reducc of "1'1"'esh":, watcr inflow,(Fig. 6). Analysis of the diagramme showed that' i~ 1994
the areaofwater with salinityover 10%~'W~s more than twice
higher wi thin S.ubarea 26 as compared to 'that in '1992 •.,Thc valtte
wi thin Russian zone from I:1arch 1993 to April-May ,1994' was more"
thari 4, times higher. ll'igure 7 shows temporal ' variations, of isolialinc
10%0 within Subarea'26.
•
To characterize conditions of codliving and,distribution in spring,
itshoul~.be noted th~t i~ohaline 10~0 occur~s the'extr~me ~order
of cod distribution area during spawnint; period wh11e the optimulli .
spawn~ng 'o.nd eggs dev'elopment conditions. ar~ observed at saf.i~ity
abov~ '11)~0 (Antonov,1.987;' Plikshs, Kalejs, Graum'ln, 1993; ','/eotiri
and Nissling 1991; lU;sling und \l/estin" 1991). Oxygen c?uditions
seems also important ,~n this.respect. Experiments by ottürlind
(1953) and mor'e recent, researches (Westin andUisslinG ,'1~91,;,'
Nisslingand Westin, 1991) showed that normal living conditions'
of cod require no less than 2 rollI of dissdlved
oxygen.
Thus, ,,the'
..
' .
, a,bove-mentioned values of salini ty .and . oxygen in, the 'long, run define
the thickness of layer, favourable fo~ cod reprod~ction.
•
.
Taking in account the above crit~riathe depth of isohaline 10lo •
and ,11%0; ~s 'weIl as isooxygen,'.S 'a.nd
. 2.0 ml/lwerc ~estimate'd 'for
various observation periods from 1992t01995.,As a result the ploto
were drawn up for temporal variability of' the layer depth favou~able (10%0-1.5 mI/I) and optima.l (11%0 .:.. 2.0 rrll/l'), for co·d,spa.wning
(fig. 0, 9). Dymnnics of nren'occupied by wntor of saiinity ab~vc
~
•
,
:
.
>
,
•
11%0 in Subarea 26 from 1992 ,to1995 is presented,in Flg. 10.
~
- 7 -
Analyoio of Pig. 8, g evidenceo that Dirnilar -Lo areu', öccupled
by highly saline'v/Uter, considerable va.riations of thicknoss of
thc layer Duitable for cod spawninß were observed during the
poriod discUSDOd. Thus, during 1992-1995 tha~ layel' thicl{ness
varied upon cxtrcmr; criteria (see above) from 3 min 'r.1arch 1993
to 30~35 m in April-~arch 1994 in Gdansk Deep, and from 10-13 m
(r.!ay 1993, April 19J3)to 2)-)2 m (April 1994, )1ay 1995) in Southern
Gotlund D80P (808 iig. 8). Howcvcr, data. of Fiß. 9 ::hould be
considered mOI'C representative estimate of optimal for cod spawning
thickness of layor, Dince the layer thicknesswas estlmated with
commonly used at present predictors, revcaling the best corrolation
betweon environmElut condi tions. and ctrene;th of individucl cod
eyear-clusses (Plik'Jhs, Kalejs, Grauman, 1993). :Pigul'e 9 Sh?"18 tha t
unlike the layer, estimated by thc criticnl boundaries ~he best conditions for spawning and hence the higher cod re~ruitrnont were obs'erved'
only in Gdansk Deep and only during strong inflow of "[resh"
Kattego.te, wa.ter in April-iViDY 1994. During other peri.ods in, deepwater arens, the thickness of layer fa'{ourable' fÜr eoel ~pawzling
decretl.sed to 5-10 m, 01' even was totally ,"wedgedö'out it which was
,stipulated
by'limitting effect of salinity in 1992, 199.3, 'especially
.
in the : area of Station Br9, und by dissolvedoxygen level in nearbottom layer during summer 1994 and early i995 (see Fig~ .3, 9).
Thus, ussessment of cod reproduction conditions on the basis of
those more rigid criteriu, allows to conclude thatduring 19921995 spawning grounds area within Subarea26 were rather restricted
.:/hile the r.1oat favourable conditions f~r cod spa'\ming and' eges
development occured in spring 1994 after two Kattegate water
inflows in January and December 1993, as was mentioned above~ ,
,
,
"
Impact of interannual variabili ty of hydr'ological conditions in
near-bottom luyers on demersal fiahes distribution in 1993-1995
was considered for cod, as one ofthe major con~ercial species.
,
,
During the second half ofApril- early 'M~y 1993, cod length'in ' '
control catches variedfrom 9.4 to 112;0 cm. The largest aggregations of cod occured at depths above 80 ,11 '.':ith near-bottom' .Vla~er
sal:i.nityover 10;;~o ( Fig. 11), \'later temperature4.5-5.3°C and
relatively high oxygen level 'over 4 mI/I. " .
Fish length in catc~es fram dee~-water area varied fram 12 ,to 112 cm
."
,
,
8 -
while individuals of'JO-55 em in length pred6minated (a.verage
length 40.5 em). Most fishes,had gonaden of III-IV maturity stages.
About
20% of flshes ware of pre-upawning
and spawning conditions.
.
.
The number of spawned females andmales eonst1tuted up to 4%.
Cod eetehes from the depth up to 80 m with water salinity nearbottorn below 9%0' at temperature of 3.2-4.0 0 C as arule navor
exeeeded 10 kg per JO-minu~e haul, i~spite'of high o~ygen level.
Cod of 9.4-90 em in length was fished while JO-55 emwas e predomi~
nated length.
Spring 199J
\vas eharaeterized by' major eoncentration cf young eod up'
to30 em in length within the same areas, asadult fish (Fig.12).
l'otal eod aatehes exceededno 200 kg. (J8kg in average).
eIn April
1994 eod catches per a. haul amounted.ip average to
84 kg while the.major aggregations were assoeiated with n~ar-bottom
water salirüty 117~o and over (Fig.13), Eit temperature 4.0-5.3°C.
Oxygen level in deep-water areas
of Gdansk Deep was high (over 2ml/I).
,
Codlengtli in catchen varied from 7 to 100 em, however' in deep~
water are~ (80 m und more) 'fishes of 30-60 emin. length predominated
while atless depths the length was 25-40 em.
Fishes with gonades of III-IV maturity stages dominated. Number
of.pre-spuwning und spuwning eod was only 2~3 %. 8mall cod of 7-15 cm
in length was eaughtmainly atdepth up to 60 m howeve~ those fishes
occaoionally were found ove!' entire area. Increuse of area with
higher near-bottom water.salinity (above 10%0) due to the North Seß
.~ater
adve'ction 'affoct()d theputtern o~ybung ccd ~istributi.on.... .
Thc highest eatches were fou.nd at dcpth of 40-90 m (Fig. 14) .·\Vi th
water ~alinity cf 7.44-12.0%0' water 'cempe~ature 2.8-5.0 o Cand
oxygen level ovcr J mI/I.
In March 1995 oxygen conditions in Gdansk
Deep and ajacent areas
,
of 90 In and lOore in depth were extrcmely ul1faVouI'n.bll~. :';Unimum
oxygenlcvel ,belavl haloclinc approached 0.12. mI/I' sometimes und
in ßeneral was balon 2 mI/I.
In bottorn. trawl catehes from such areus cod was absant or occured
rarely (l"ig.15) ~ Illajor aggregations were faund' at the depth of
90
In
und less.
Avoro.{!.e cod cutch per JO-minute Imul umountod
1;0
109 kg. In the western part of investigation area nortb0arus of
•
,9':-
"
Gdansk Deep at the dapth af 83-90 m the length of eod' in eatcheo
was 19-90 cm, predominated aize- 43-63 cm, average length ~ 54.0 em,
Eastwards und northwards of the paor axygen area, at tho depth
of' 38-90 m the length of eod in eatcheswas 11-'-103 em,' prcdominated"
size
-'26-65 eID, average length
-37.7
~m. The'bulk of;~ature 6~d"
.
.
.
had gonades of III, IV stages while thonumber of pre-spawning
,
and spawning eod was anly 1-2 %.
'.
.
,
Young eod,
30 cm in length distributed mainly in~theareas' of
,)8-74 m in depth,at near-botto~water·salinityof 7~)-10~c' (Fig~16),
temporature, - )-5°0 und high .-oxygenlevel.
Relation of eod distribution and' oxygen level .
in "
near-:-bottom 'layers . '
was observed by many authors, ,ineluding M.Berner, R.Schemainda'
(1958), described similarsituation in Bornholm Deep.
"
4t
Those authors', showed: thatin the areäsof low oxygen level in'
ncar-bottom 1ayers flsh was d{stri~uted in~e1agie'~onc Qnd is
unavailable to a bottom tro,\",l. Excluding' no, such situation, we
should note, that our date . on cod distributi~n
IlIarch" 1995
.
.
evidence-considerable inercase of young fish number around anoxie
areas at' 1ess dep~h with high oxygen level.'
in
,"
OONOLUSION'
In 1992-1995signifieant variations of hydrologieo,l condition3
were found in the South~EasternBaltie Sea, especially in dcep
"waters which was the, result' of, the Kattegate water inflow in, tJanual'Y
•
and, December of ,1993.
,
Due·to a.dvection Cle~iation'of 'salinity values' fl''om long-term
a.verage' 'decreased by 5-10 tim~ri.', In
1994 salinity innear':"
bottom'l~yerofGdD.nsk,Dee'p exceede'd. the' latter.,J!1~r the first' time
,d~ring,.l~styears'salinitYvalue,in Gdansk Deep was over 1J~o~ und
th<it in .Gotland Deep - over.12~0.'
One of 'thc most essential'~onsequences of the Kattega.te, water,
I
' "
•
.
~
.
:
\
,-
inflow was the comple:tion of the.l~ost long for the century \ov~r
15 ~ears) stagnationperiod,il:i',theEastern
Baltic Sea' in· summer
..
.
.~
1994.
~
i
•
'
.
Assessment . of arens, occtipied~ by wat'erof higher salini tj (1 Qibo )
for :Subareu . 26 ßh~wri" totalinc:t'I)E'~DC'by:
2
times, a.nd inerea.se ,in
Russian zöne by'abo"e IL' times fram, Rprine; '199'd, 1993till :1ay 1994.
-
10 '-
. Another consequence of h.igh salini ty water intlow Wl;ttl lJue
inerease of water column stratifieation whieh in couple with
warm wiriter of 1994/1995 resulted in anaerobicprocess~s develop-.
ment in a'deep part of, Gdansk'area where oxygen'defieieney (0.10.7 ml/l) was observed·not only in March, but eVen in May-June 1995.
Analysis of environment. variabili t;y' in cod spawnirig' grounds
shows that from 1992 to 1995 themost favourable .eonditiOl1S for
spawning and eggs development within Subares. 26w~ in spring
1994 during raximmn advection for the period concorned.
•
During spring major aggregations ofadult cod were observed in
the deep-water areas with salinity cf near-bottQm l~Ye; above
10%0 and'oxygen level of 2 mlll und more. Water'salinity and·
temperature restriet·····young eod distribution to the less extend
while adult pre-spawning and spawning 'eod prefered highersalinity
and temperatu~e of water. Oxygen deficiency resulted ·in cod migration
into nearbY areas wi th oxygen level of . , 2 mlll aild more. HoweveI;'~'
pre-spawning and :spawningfish which prefer areas w1th higher
salinity, distributed .around "anoxie" zones and,' possibly, in
pelagie zone over oxygen-defieieney Iayer •
l
•
.
- 11 -
REFERENCES
e
Anon. 1994. Heport of the working group on the baltic marine environment. C.W.1994/E:3.
Antonov A.E. 1987. Large-scale variability of hydro~eteorological
conditions of the Baltic Sea.and its impact on fishery •. L.Hydrometeoizdat, 247p.
Berner M.,Schemainda R. 1958. fiber die Abhängigkeit d~r Laichdorscherträge im Bornhoimbeiken von der hydrographischen Situation.'
'Deutsche Pischereizeitung,Nr. 3, Berlin.
Plikshs M., M.Kajes, G.Grauman. 1993. The influence of environmental
conditions and spawning stocksize on the year~c~ass strength
of the eastern Balticcod.-Riga, 1Jp.
Ndssling A. and \'Iestin L. 1991 • Egg mortality ~nd hatching rate
of Baltic cod (Gadus morhua) in different salinity. Marine
Biology, 111:29-32.
Wes tin L. and N'issling A~ 1991. Effect of salinity on spermatozoa
motility, percentage of fe~tilized eggs and egg development
. .
oi :ealtic cod (Gadus Morhus.) and implications for cod stock
fluctuations in the Baltic. Marine Biology, 108:5-9.
Zeze'ra A., E. Zezera.~ 1993. Water salini tyvariahili ty and anomalies"
in the South-Eastern Baltic Sea (1992-1993). 'ltaliningro.d.
'
Table 1.
Water sallnity (average four each standard stations) and its deviation fram the mean long-term values (0100)
in spring and autumn 1992·1995 (the Gdansk Deep).
N
N
Cl
Cl
>.
....
(ll
::2
>!ii
E
0
c:
«l
C1l
(J)
..-
....
Q)
.0
.9
IJ
m
E
0
c
(ll
0
Ol
Cl
.....
.c
~
l'!l
~
V
C")
C")
>.
~
(ll
E
0
c
(ll
C'?
Cl
Cl
.....
>.
co
~
>-
m
E
0
c
(ll
0)
Cl
...0.-
Q)
.0
2(ll
E
0
~
C
CD
-0,2
'<t
Ol
....
Q)
'-
0<{
2(ll
E
0
e(ll
0
v
m
Ol
..>.
llJ
~
~
ca
E
0
c
ltI
m
>.
llE
Cl
..-
.t:)
o
Ü
0
äi
c
c
CD
lI)
0)
C1l
...c
~
(tJ
:2
~
(ll
E
0
c
co
lI)
0)
....
01
I
2('{l
I II
>.
(ll
:a;
E
0
c
I
('Cl
-{
Layer
0·50 m
7,2
-0,4
7,3
-0,'3
7,5
-0,1
7,3
-0,3
7,4
Near-oottom
layer
10,2
-1,3
9,8
-1,9
9,1
-2,4
11,3
-0,2
11,1 . -0,6
Whcle layer
8,1
-0,6
8,0
-O,g
7,9
-0,8
8,5
-0,2
8,7
..0,1
7,4
-0,2
7,2
-0,4
7,2
-0,4
7,4
-0,2
7,4
-0,2
11,7
0,2
12,3
0,8
11.8
0,1
11,0
-0,5
11,2
-0,3
8,5
-0,2
8}
0,0
8,4
-0,4
8,4
-0,3
8,4
-0,3
..-
- 13 LEGENDS
e
. Pigure 1. Heseurch Hr'ell und loeation of international deep-water
stations.
Figure 2. Sa1inity distribution (%0) in the nea~-bottom layer
(1992-1994).
Pigure J. Sulinity and oxygen ., variations ,in near-bottom 1ayer from
1992 to 1995 (Subarea 26.).
PIßure 4. Spatia1-tewpora1 variability of temperature, sa1inity und
oxygen from 1992 t6 ,1995.
Pigure 5. Spatia1-tempora1 variability of temper.atura, salinity
und oxygen from 1992 to 1995.
Figura 6. Variability of areal(sq.miles) oeeupied by water with
salinity above 10%0 (Subarea 26) •.
~'igure 7. Variabi1ity of 10%0 isohaline 10eBtion in spring 19921995 ..
Figure 8. Dynnmics of the 1ayer favourable for eod spawning from
1992 to 1995 (Subaren 26).
Pigure 9._Dynamies of the 1ayer,. optimal for cod.spawning from
1992 to 1995 (Subarea 26).
'Pigure' 100 Variation of 11%o,isohaline in spring'1992-1995.
Pigure l'i. Watel' salinity in near-bottom 1ayer and cod catch'3s per
JO-minute hauls in April-May 1993.
Figure 12. Water salinity in near-bottom 1o.yer and eatch of cod
of JO cm in length in April-May 1993.
Figure 1Jo Water salinity in· nem'-bottom 1ayer und eod eatehes per
Ja-minute hau1s in April 1994.
Figure 14. Wnter salinityin neal'-bottom 1ayer und catehes of eod
cf 30 cm inlength in April 1994.
PIßure 15. \7ater salinity innear-bottom 1ayerand eod cai;ches per
JO-minute hau1s in April 1995.
l"igure 16. \Vater 88.1ini ty in near·-bottom layer and catches of eod
of 30 em in lengthin Mareh 1995.
Table 1.
Water &<llinity {a'l~rage tour each standard stations) and its deviation from the mean long-term alues (0/00)
in spring and autumn 1992-1995 (the Gdansk Deep).
~
I I~
h~--=-L.'!lj8-'-.~
I
l'~
I
ayer
0-50 m
~~ i
~
~
g
M
z:,
Cl
0)
...-.c.
eil
E
0
2
c-
cu
(Il
I :c
aI
E
0
e
('Cl
~
M
(")
0>
C1l
.,....
>.
III
~
C1l
>.
(ij
Cl
G)
E
...-
...
E
0
..Cl
c:
0
('Cl
~
z:,
-'
0
III
0
c:
(ll
0
V
Cl
01
'C
4:
z:,
E
...-
E
e:
eil
~
aI
..-0-
~
I
Q)
Q)
0
>.
lt'
~
CD
0
c:
('Cl
Cl
Cl
........
(ö
..Cl
C
G)
0
t>
-
L{)
>.
E
c:
aI
0
C1l
....
.c.
...
0)
U
('Cl
~
~
m
E
0
c:
aI
L{)
Q)
C1l
.,....
>.
III
~
(;j
E
0
c:
m
7• I 2
-0 4
73
-0 3
7,5
-0,1
7,3
-0,3
7,4
-0,2
7,4
-0,2
7,2
-0,4
7,2
-0,4
7,4
-0,2
7,4
-0,2
0,2
- ,3
9,8
-l,gl
9,1
-2,4
11,3
-0,2
11,1
-0,6
11,7
0,2
12,3
0,8
11,8
0,1
1 ,0
-0,5
11,2
-0,3
-0,6
8,0
-08
,
7,9
-0,8
8,5
-0,2
8,7
-0,1
8,5
-0,2
8,7
0,0
8,4
-0,4
8,4
-0,3
8,4
-0,
)
f
I
"
I
f---.
N ar- ttOI.1
layer
IWhole layer I 8,1
-
!
II
i
I
,I
21,5
/-----'-----"""--...-;..--'------'----+---......... 56,5
18,5
19
19,5
20
20,5
21
•.
IBY9! /':
...:
..
56 .
\~
•
\
·55,5.
\....
~\1
55
~" .. ,.....
L
54,5
--L
Flg.1.
54
•
e
zoO
l~f
, "
lSiG'!
,"
'i,
,
19'
J.
>
20'
'.,
:;;
..
tL
i
I
,.:....
i
I
Li •••
.
'
'-.~
{
•
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I
•
~/
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11!
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)~"..
.
"
.
i
vi
,
J
.
',.
I
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,
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ty
r~arch
\
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i
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,IV
I
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HO
12
,)[12
Ilf
. . .~'. ~~
I'fil
2~~~'
/
'/
~~ ~'
OC1;ober 1993
I
,.
Z~
;f~.,
;
April 1994
I
'
IMa~
/7 /; -.
1994
..l..:L-')
1///_'
~;S7'-- ,
l
I
56"
---
\\~(~ 7.~
/
,:
\.
A~'=
.~\
~ B~,
.'
~
\::: 9 --.......... ~ . ~~_. "
.~
, ,.,' -13
lD~ \ _,' l . - 1 1IO!......"""\
If
ßl'-'
~ ~"
'.
I St/'3r/H
(I
Aprll-May 1993
1993
;;
~
'\.
,:,~
H
,
ig.2.
'0'30'
4- SI
,
IO'~'8 jPR
;
October 1992
i
I
:/:JIt~
~~
~
. (,,<
J
~.
JA
Ir'
10"
>
} \9J"~
H
~~.. ,j,
,iZ~:~i,rot!~'{".~/
- ,I
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1,'1
( '."
\t··~'
n)
• . •,. . . . .
19'
'
"
/ j:l;JI
.......
.
I
, I .1,...-
-,""~
10'7
20'
19'
. - r ss·
, /./ /','
Oc-t 0 bel" 1994
1 5113D 'N
e
e
...
o
."
c'
~
Sa!inity
......
...
...
': : : rs
...
...
.:..
'"
IV
!tiil
I ~I
Salinity
...
......
e
...
:;:
t.>
N
, 'rn I
05.1992
LP..J
1(j.19S2
-0
'.
I
------.:~o
.
03.1993
04 1993
I
--~
04 1993
...... ' - " - "
10.1993
.....
-.
.....0'
)
10.1993
041994
04.1994
(
.... _ ..-v
~
I- - - _ . _~
...-0 ....
1)5.1994
OS.19~4
10.1994
.-Q
10 1994
\
03 1995
t
03 19S5
05.1995
n5.1~95
o
~
I.....~~ . ~.... ~
I
N
(".)
.:..
O~"''gen
o
N
cn
0
.::; 03 0
<.1'
(J)
o
I
i
:v
I
,..
~
OIYg e
:: 11
I~
0
'3 0S 0
I
i
t."'t
Ot
. ~·-T~T
~
~"
65
~_,
Tw
..~_~~
::l~~·
105
-
•
'U
!'l
/11
...
1(;
tr.
0
f"iq . 4.
C'J
I')
P')
I')
lJ)
01
Cl
1JI
01
~.
ci
....
P--1
...
01
"j
0
...-i
/]I
0
01
"t"
0'
\7)
ci
,-
0
...
...
-i
'...."
(J)
01
ori
0
f
I
'<t
0\
Ol
...
...ci
III
Cl
Cl
.-
n
0
III
0,
<1>
...
III
0
BY9'
30
'1O
60
70
80
90
100
110
120
r--.
:::E
'-"
10
20
30
,,0
J:
.-:.
::./..--'_
60
70
Cl.
7,S~-:'lr'
. ~/ SO/OO
50
80
SO
w
1M
Ö
120
110
~
~.()
~ /'-
~ ----9~:~/\~.---'
lJ
/ ' 0,0
......
~
1~
. /'~,()~.
I.
~O n
//
'V
~
.
~ ~-I-"/\lr-rT==Y==~:;===~
JO
F
40
1-.
I
,,()l
:: -'"
110
120
t
1.c:D·
~'-
~,
m
m
~
~
~.
0,
~
. . .~. . .
...
.
1")'
0,
~
0
02 mI/I
".J- ..
~
..
-1..,--,---1-1_.L..L-.....J
o~
11)
"
.~~
\)
I")
~
Fig. 5. .
.
C'l
m
I
(l)
@
~_
I~
ci
...
.
v
0
~
m
())
...
0~
~
01
...
o'
~Jl
~
~.
~...
0
'.>.
01
.
n~'
•
2590
-
-- --- .. -. "'-'
-.. -.-
--
-. -- ..-..-.-
-
-
-
"
-..
--,
OS10%o
20110
DS10%oRUSSLI\
1500
•
1603
Cl
......
N
""
....
~
.......
N
."
a
....
Fig.6.
......""
....on
C">
..,;
e
.
....
....
..tc:>
....
....""a
0>
.....
..,.
.....;.""""
...
....
....
.,.
..-;
""
C>
...
......
cl>
~
......
....,.
on
C>
on
.,.
.............
."
18.5 E
19.0
19.5
20.0
.20.5.
21.0
21.5
22.0
I
56.ö
56.0 .
•
55.5
.-
55.0
o Koliningrod
•
.'>4.5
54.0 N
Fig. 7.
e
e
----
'"Ti
ii
•...,..,,>,:-. l!] ....
:~~
P
05.1g92
I
0.5.1992
j
10.1'"
',"',
[]Ij
.• & .•
......,....
10.1992
.
03.'\993
04.1993
:i':'-:":';'-";"~':'::;''\--_''''''''''------...j
. . . . - . . ---j
y:.:.".:.;.:.
::.::;;.;::.:.;.;:::::;'-~
04.1993
, -llO·""
1G.1993
!
"
I 05.1994
:{',
I 10.1994
--. 10.1994
03.1995
>.j
-
_._~
....
....o
....
....
'0
I 05.1995
:-.
..
<:)
<:)
...o
Deplh (m)
""o
.....
o
!
0>
o
03.1995
t
I
'i----
04.1994
04.1994
v
~
~
o
I 05.1995
[~
0
0
~
~
~
000
Dsplh (m)
~
0
~
0
.
e
e
·::---······__·_·····_·····_···· ....
f......•.
~
.."'O
••
'7
-n
cö'
.""
>
tO
\
,
_
j 05.1994
_
I
; -..~..-
I~'+ ~;~
~
~
0
CO
0
"
N
~
0
0
j
~
0
Deplh (m)
rrr-n
!UlO<n,0
N
...
L~.~ ~j
1
..............•.......
03.1995
/:::::!:i:;.
:- ) 05.1995
,:j:;+j;;:j:\;j:::j:/
~
0
c·
C
_
Lr----·--·-
·············'··~--11~.19S4
,. ..-.-.--.--- --.1
...•._-.... ~ 04.1994
__ ._;
\\
"
------1 04.1993
<;c,c,;,;~:~;;~'~r·····--I ".,'"
04.1994
~
"'" ~-.;: ,
10.1992
03.1993
TJ~>T~-
10.1PS3
05.1992
-0
0
<:>
-
--
03.1995
_-_ _.._ -
...
co
'e;.,
0
...,
0>
Q
0
Deplh (m)
mll"'1
lto~
ö
0
t,)
f'...)
' 11
"0
3 b 0-'
I ~ j
O~.1994
05.1995
...
CI
..
18.5 E
19.0
19.5
20.0
20.5
21.0.
21.5
22.0
56.5
56.0
•
_.
55.5
55.0
•
54.5
54.0 N
Fig. 10.
...
.
18.5 E
19.0
19.5
20.0
20.5
21.0
21.5
22.1;)
56.~
56.0
55.5
55.0
o
Kaliningrod
o i
•
•
2
•
3
54.5
.G) 4
17.04-03.05.1993
L--
..---
.....::....-
Catch In kg
1) 0;
2) '50;
3) 50·100.;
4) 100-200.
Flg.11.
---J
54.0 N .
18.5 E
19.0
lr----r--
19.5
. .5
20.5
20.0
~3T7~~~2~1~.O~
.21
22.0
-1
56 5
.
I
.
I
7.24
.
-1,
7.+2
ca
56.0
7.31
o
>
\1
l,
,.
'A;.
,...
"'.1 ::>
IL
17.04-03.0~.1993
-----
54.0 N
Catch
1\ O. In memoers
2}
~
10'
3) 11-20'
.
21-30 .
,
4)
F'ü-. 1 .
5) 31-50;
6) 51-80;
7) 8-1 -1"
,- ,,0 .
I
6) 121-150
•
18.5 E
19.0
--r
19.5
20.0
20.5
21.0
22.
21.5
56.5
I
-1
5500
Q
oo
~
,::; 6
'J
05-20.04.1994
- - - - - - - - - - - - - - - - - - - ' 54.0 N
Catch In kg
1) 0;
5) 200-300;
2) ~ 50 ;
6) ~00-400;
3) 50-100; 7) 400-500;
4) 100-200 8} > 500 .
Fit]. 13.
.
18.5 E
19.0
------,
19.5
20.0
20.5
21.0
21.5
22.0
\1
565
J
56.0
•
5.5
0
0
.,c:.-1
55.0
3
4
,
r;
,..l ••~:) 6
,
.
'l
~'
54.5
7
05- 20.04.1994
54.0 N
The same, es on the Fig. 12.
Flg.14.
•
18.5 [
19.0
19.5
20.0
20.5
21.0
21.5
22.0
56.5
56 0
1
.
o
7.32
'e.
-
o
f}
55.5
55.0
i
2
3
.~
4
5
6
-
05-25.03.1995
---.--------:--------..
The same, as on the Fig. 13.
Flg.15.
54.5
54.0 N
18.5
E
19.0
1 .5
20.0
20.5
21.0
21.5
22.0
~
55.5
i
I
o
i
-i
I
......
I
(0 '
o
I
I
I
Kaliningrad
r··
~.
' 7
>' :~
,,* .
05-25.03.1995
;.:Y .
The same, as on the Fig. 12.
Fig.1 .
55.0
~I'
54.5,
J
54.0 N