Coas al and eshwa e pikepe ch (Sande luciope ca) popula ions
di e gene ically in he Bal ic Sea basin
MARJATTA S Ä IS Ä 1 , MATTI SALMINEN 2 , MARJA-LIISA KOLJONEN 2 and JUKKA RUUHIJ Ä RVI 3
1 Depa men o Ag icul u al Science, Uni e si y o Helsinki, Helsinki, Finland
2 Finnish Game and Fishe ies Resea ch Ins i u e, Helsinki, Finland
3 Finnish Game and Fishe ies Resea ch Ins i u e, E o, Finland
S ä is ä , M., Salminen, M., Koljonen, M.-L., and Ruuhij ä i, J. 2010 . Coas al and eshwa e pikepe ch ( Sande luciope ca )
popula ions di e gene ically in he Bal ic Sea basin. – He edi as 147: 205–214 . Lund, Sweden. eISSN 1601-5223. Recei ed 26
Ma ch 2010. Accep ed 6 July 2010.
Mic osa elli e DNA based analysis o he pa e n o gene ic di e si y among h ee coas al and i e eshwa e popula ions o
pikepe ch Sande luciope ca in he no he n pa o he Bal ic Sea d ainage basin indica ed ma ked gene ic di e en ia ion be ween
he coas al and lake popula ions. The F
s be ween hese popula ion g oups was as high as 0.25 and R
s ⫽ 0.32. In gene al, he
lake popula ions showed highe gene ic di e si y han he coas al ones. In e ms o gene ic dis ance, he h ee coas al popula ions
(Vanhankaupunginlah i, V ä s an j ä d and Tai assalo) g ouped igh ly oge he . The eshwa e samples o med a loose g oup, in
which he no he n Lake Kemij ä i showed g ea e dis ance om he sou he n lakes han hese did om each o he . The wo lake
popula ions o iginally es ablished h ough s ockings (Lakes Painio and A e ia) g ouped nea o hei sou ce popula ion o Lake
Lohjanj ä i and hei di e si y le el was nea ly he same. Sa egua ding he unique Bal ic coas al popula ions o S. luciope ca
agains gene l ow om inc easing ha che y eleases using eshwa e S. luciope ca should be a high managemen p io i y.
Ma ja-Liisa Koljonen, Finnish Game and Fishe ies Resea ch Ins i u e, PO Box 2, FI-00791 Helsinki, Finland . E-mail: ma ja-liisa.
[email p o ec ed]
The pikepe ch ( Sande luciope ca ) is a Eu asian eshwa-
e species ha is widely dis ibu ed in wa e cou ses
l owing in o he Bal ic Sea, Caspian Sea and Black Sea.
The sou he n limi o he species ’ na i e ange ex ends
om sou h o he Alps o he Py enees, and he wes e n
limi is he Ri e Elbe unning o he No h Sea. The
S. luciope ca did no o iginally occu in any i e s en e -
ing he A c ic Ocean, bu has been in oduced o some
o he i e sys ems o no he n Russia. In wes e n
Eu ope, he S. luciope ca has been in oduced in F ance,
Belgium, he Ne he lands and G ea B i ain. In oduced
popula ions also li e in Tu key and Mo occo ( DEELDER
and WILLEMSEN 1964). Al hough he S. luciope ca h i es
in wa m eshwa e , i also endu es limi ed salini y and
o ms speci i c local popula ions in coas al sea a eas whe e
he salini y is no oo high (abou ⬍ 5 psu, p ac ical salin-
i y uni s; WINKLER e al. 1989; LEHTONEN e al. 1996) and
wa m shallow spawning a eas a e a ailable in he sp ing.
B ackish wa e popula ions a e hus widely dis ibu ed in
he es ua ies and coas al a eas o he Bal ic, Black and
Caspian Seas.
Despi e he de ailed bio-geog aphical, and g adually
accumula ing gene ic knowledge o he Eu asian S. lucio-
pe ca popula ions ( POULET e al. 2004, 2009; BJ Ö RKLUND
e al. 2007), no plausible hypo hesis has o ou knowledge
been sugges ed conce ning he po en ial pos glacial colo-
niza ion ou es o he species. Al hough he S. luciope ca
ole a es b ackish wa e , e-coloniza ion mos likely
s a ed om some o he pos ula ed eshwa e e uges
( NESB Ø e al. 1999), oge he wi h ce ain o he esh-
wa e species. In a ecen s udy o he mic osa elli e a ia-
ion o S. luciope ca in Scandina ia ( BJ Ö RKLUND e al.
2007), s ong gene ic s uc u ing was obse ed, po en-
ially indica ing long- e m isola ion pa e ns ela ed o
coloniza ion his o ies.
In Finland, he S. luciope ca is among he economi-
cally mos aluable i sh species and is impo an o
bo h comme cial and ec ea ional i she men. Due o he
high i shing p essu es, many Finnish S. luciope ca popu-
la ions ha e been subjec ed o g ow h o e - i shing
( HEIKINHEIMO e al. 2006) and some o hem e en o
ec ui men o e - i shing ( COLBY and LEHTONEN 1994),
despi e he nume ous managemen measu es aken o
egula e i shing, including minimum landing sizes, mesh-
size egula ions, es ic ed seasons and p o ec ed a eas.
Ex ensi e enhancemen and e-s ocking p og ams using
pond- ea ed ju eniles ha e also been ca ied ou o e en
ou na u al l uc ua ions in ec ui men , o mi iga e he
e ec s o o e - i shing o o c ea e new i shing oppo uni-
ies ( RUUHIJ Ä RVI e al. 1996).
In economic e ms, he s ocking p og ams ha e gene -
ally been conside ed as sus ainable: ca ches ha e
inc eased and se e al new i shable popula ions ha e
been es ablished ( LEHTONEN e al. 1984; RUUHIJ Ä RVI e al.
He edi as 147: 205–214 (2010)
© 2010 The Au ho s. This is an Open Access a icle. DOI: 10.1111/j.1601-5223.2010.02184.x
206 M. Säisä e al. He edi as 147 (2010)
1996, 2005; SALMINEN and RUUHIJ Ä RVI 2004). Gene ically,
he eleases may ha e been less sus ainable. Due o
insu i cien con ol and planning o he eleases and
he low numbe o comme cial pikepe ch ha che ies,
p ac ically all s ocking p og ams ha e elied on only
h ee o ou di e en pa en popula ions, all o hem
wi h a sou he n o igin. This p ac ice has p obably
esul ed in a la ge-scale loss o he o iginal gene ic
di e si y wi hin he species. Du ing he las wo decades
mos Finnish pikepe ch popula ions, especially hose
li ing in eshwa e sys ems, ha e been subjec ed o
he l ow o o eign genes h ough ha che ies ( TOIVONEN
e al. 1981; Fig. 1).
The ecen boom in ha che y eleases has no ye
eached coas al a eas, mainly due o he con inuously
ela i ely high na u al ec ui men o he b ackish wa e
popula ions ( RAITANIEMI and MANNINEN 2007), p omo ed
by he con inuing eu ophica ion o he Bal ic Sea. This
o e s he manage s o he coas al Bal ic Sea i she ies
an in aluable oppo uni y o once mo e ho oughly
conside he long- e m sus ainabili y o he sugges ed
u u e enhancemen and e-s ocking p og ams, no only in
economic bu also in gene ic e ms. The alue o he Bal-
ic Sea as a unique en i onmen has been widely ecog-
nized (e.g. HELCOM Bal ic Sea Ac ion Plan, ⬍ www.
helcom. i ⬎ ) and p ese ing he gene ic di e si y o he
i sh popula ions adap ed o he speci i c condi ions o
he Bal ic Sea should be one o he main p io i ies a all
le els o decision making.
De ailed knowledge o he gene ic s uc u e o he
exploi ed i sh popula ions is a p e equisi e o hei suc-
cess ul long- e m managemen . The aim o his s udy
was o p o ide be e ools o he e alua ion o di e en
i she ies managemen al e na i es in coas al a eas by
desc ibing mic osa elli e DNA a ia ion in Finnish pike-
pe ch popula ions and o assess he le el o gene ic
di e si y and especially he po en ial di e en ia ion
be ween coas al and eshwa e popula ions. The gene ic
s uc u e de ised om neu al ma ke a ia ion indica es
he gene al le el o isola ion and he ime ha has been
a ailable o adap i e e olu ion.
MATERIAL AND METHODS
Samples
Eigh pikepe ch popula ions we e sampled o he gene ic
analyses, h ee o hem ep esen ing he coas al and i e
he eshwa e dis ibu ion o he species (Table 1, Fig. 1).
As he aim was o in es iga e he na u al gene ic di e en-
ia ion o he species, i.e. di e en ia ion p eceding he
p esen boom in ha che y eleases, and hus be o e majo
human impac , he sampled popula ions we e chosen on
he basis o hei eco ded managemen his o y ( HALME
1961, 1962; TOIVONEN e al. 1981), and he a ailabili y o
ep esen a i e samples. Fo some cases, old scale samples
we e used o a oid he in l uence o ecen gene l ow om
ha che y eleases.
Coas al, b ackish wa e popula ions
Tai assalo (Fig. 1, sample 1) and V ä s an j ä d (sample 2)
a e impo an pikepe ch i shing a eas in he Finnish
A chipelago Sea, whe eas Vanhankaupunginlah i (sample
3) is he spawning es ua y o a pikepe ch popula ion in
he Gul o Finland (Fig. 1). Tagging s udies ha e indi-
ca ed ha pikepe ch li ing in he di e en bays, sepa a ed
by chains o islands, belong o dis inc spawning popu-
la ions ( LEHTONEN 1985). Due o hei ela i ely high
ec ui men du ing he las 15 yea s ( RAITANIEMI and
M ANNINEN 2007), he coas al popula ions ha e so a no
been a ec ed by signi i can ha che y eleases and, he e-
o e, esh samples om he ea ly 2000s could be used in
he analyses.
050100 km
Dis ibu ion in o ma ion © FGFRI 2003, Lakes and i e s © ESRI 1999,
Wa e shed bounda ies © Finnish En i onmen Ins i u e 1997
NNNNN
1
23
45
6
7
8
Finland
Fig. 1. The occu ence o pikepe ch s ocks in Finland and he
loca ions o pikepe ch sampling si es. Numbe s 1 – 8 e e o
samples desc ibed in Table 1.
He edi as 147 (2010) B ackish and eshwa e pikepe ch di e gene ically 207
s ong and s able pikepe ch popula ion, Lake Vana-
janselk ä suppo s impo an pikepe ch i she ies and has
also been used as a pa en popula ion o la ge-scale
ha che y i nge ling p oduc ion ( RUUHIJ Ä RVI e al. 1996).
Despi e he good condi ion o he na i e popula ion, and
he good a ailabili y o indigenous s ocking ma e ial,
la ge-scale ha che y eleases using a o eign pa en popu-
la ion ( om Lake Painio) ha e ecen ly been ca ied ou
in Vanajanselk ä . The e o e, old scale samples om he
in ac yea classes 1984 – 1986 (20 ind./yea class) we e
used in he analyses.
Lake Kemij ä i (Fig. 1, sample 8) (23 000 ha) is one o
no he nmos na i e pikepe ch lakes in Scandina ia
( TOIVONEN e al. 1981). Un il he 1970s he pikepe ch pop-
ula ion o Lake Kemij ä i was ela i ely s ong and sup-
po ed impo an local i she ies, bu has since hen
dec eased o a e y low le el. Despi e he p esen poo
condi ion o he popula ion, no ha che y eleases ha e so
a been ca ied ou in Lake Kemij ä i. Hence, esh sam-
ples om he yea classes 1998 – 2003 (1–40 ind./yea
class) we e used in he analyses.
DNA analysis
To al genomic DNA was ex ac ed om i n, muscle o
scale samples by using a DNA DNeasy 96 Blood and Tis-
sue Ki (Qiagen, ⬍ www1.qiagen.com ⬎ ). Va ia ion in he
ollowing 12 mic os elli e loci was de e mined: P l aL2,
P l aL3, P l aL8, P l aL9 ( LECLERC e al. 2000), S i4, S i6,
S i18, S i33 ( BORER e al. 1999), S iL7, S iL8, S iL9 and
S iL11 ( WIRTH e al. 1999) (Table 2).
PCR we e pe o med in a 10 μ l eac ion olume con-
aining 1 ⫻ bu e o DyNA zyme (Finnzymes, Espoo,
Finland, ⬍ www. i nnzymes.com ⬎ ), 0.2 mM o each
dNTP, 5 pmol ( P l aL3, P l aL8, P l aL9, S i4, S iL7, S iL8,
S iL9, S iL11, S i18 and S i33 ) o 10 pmol ( P l aL2 and
S i6 ) o each o wa d and e e se p ime ( o wa d p ime
l uo escen ly labeled), 0.1 U ( P l aL8, S iL9 and S i18 ),
F eshwa e popula ions
Lake Lohjanj ä i (Fig. 1, sample 4) is a medium-sized
lake (8900 ha) suppo ing impo an pikepe ch i she ies.
The na i e pikepe ch popula ion o he lake ( TOIVONEN
e al. 1981) has since 1991 been s ocked wi h ha che y
i nge lings om h ee o eign lake popula ions: Lakes
A e ia (sample 5), Painio (sample 6), and Vanajanselk ä
(sample 7) ( SALMINEN e al. 2005). The e o e, old scale
samples ep esen ing he s ill in ac yea classes 1979 –
1981 (20 indi iduals om each yea class) we e used in
he analyses.
Lakes A e ia and Painio ep esen ypical smalle
(140 ha and 780 ha, espec i ely) Finnish pikepe ch
lakes. The pikepe ch popula ions li ing in hese lakes a e
no na i e, bu ha e hei oo s in he old in oduc ions o
he la e 1800s and ea ly 1900s ( HALME 1961, 1962;
T OIVONEN e al. 1981). Un il he 1970s, pikepe ch had
been success ully in oduced o a o al o 94 lakes in
sou he n and cen al Finland ( TOIVONEN e al. 1981). In he
case o Lake Painio, he pikepe ch we e ans e ed as
adul i sh in 1932 and as e ilized eggs in 1938 om Lake
Lohjanj ä i ( HALME 1961, 1962). The sou ce popula ion
o Lake A e ia is no known (in oduc ion in 1930 – 1950;
T OIVONEN e al. 1981), bu Lake Lohjanj ä i is also he e
he mos p obable candida e.
Since he la e 1980s, bo h Lake A e ia and Lake
Painio ha e been used as sou ces o b ood i sh o la ge-
scale ha che y i nge ling p oduc ion, and as iable popu-
la ions wi h con inuously ela i ely s able ec ui men
hey ha e no been a ec ed by eleases o o eign pike-
pe ch popula ions. Fo Lake A e ia, he sample ep e-
sen s he yea classes 1979 – 1982 (4 – 35 ind./yea class),
and o Lake Painio, he yea classes 1985 – 2005 (0–16
ind./yea class).
Lake Vanajanselk ä is he la ges lake (10 300 ha) o he
wa e cou se inhabi ed by na i e pikepe ch popula ions
( TOIVONEN e al. 1981). Wi h a con inuously ela i ely
Table 1 . Si e, sample size, sampling yea , yea classes and o igin o s udied pikepe ch samples.
Si e n Yea Yea classes O igin
Coas al samples
1 Tai assalo 60 2001 – 2005 1994 – 1999 na i e
2 V ä s an j ä d 60 2003 – 2004 1995 – 2001 na i e
3 Vanhankaupunginlah i 60 2004 – 2005 1997 – 2002 na i e
Lake samples
4 Lake Lohjanj ä i 60 1982 – 1986 1979 – 1981 na i e
5 Lake A e ia 63 1984 1979 – 1982 in oduced
6 Lake Painio 74 2006 1985 – 2005 in oduced
7 Lake Vanajanselk ä 60 1988 – 1991 1984 – 1986 na i e
8 Lake Kemij ä i 60 2006 1998 – 2003 na i e
All 497
208 M. Säisä e al. He edi as 147 (2010)
we e analyzed wi h he GENEPOP 3.2 so wa e package
( RAYMOND and ROUSSET 1995) wi h Ma ko chain pa am-
e e s, 300 ba ches and 3000 i e a ions. P obabili ies o
H-W equilib ium es s o samples we e adjus ed o e loci
using he sequen ial Bon e oni p ocedu e o mul iple
es s ( RICE 1989).
The expec ed he e ozygosi y le el in each sample was
calcula ed using Popgene e . 1.32 ( YEH and BOYLE
1997). Analysis o he di e ences be ween samples was
based on allele equency di e ences, using pai wise F
s
alues ( WEIR and COCKERHAM 1984), which we e es i-
ma ed wi h FSTAT e . 2.9.3 ( GOUDET 2001). S anda d
de ia ions and con i dence in e als we e es ima ed
h ough boo s apping. R s alues and an allele size an-
domisa ion es ( HARDY e al. 2003) implemen ed in he
p og am SPAGeDi 1.1.b ( HARDY and VEKEMANS 2002)
was used o es whe he s epwise mu a ions ha e
con ibu ed o he gene ic di e en ia ion among popu-
la ions, i.e. whe he R s ⬎ F s . A signi i can ou come o
he es sugges s ha popula ions ha e di e ged o a
su i cien ly long ime o mu a ions o ha e con ibu ed
signi i can ly o di e en ia ion, which could be he case
i popula ions ha e o igina ed om di e en glacial
e ugia. Gene ic dis ances be ween samples we e calcu-
la ed using NEI ’ s D A dis ances ( NEI e al. 1983). A phylo-
gene ic ee was cons uc ed using a neighbou joining
(NJ) algo i hm ( SAITOU and NEI 1987) wi h DISPAN
so wa e ( OTA 1993). Boo s apping wi h 1000 eplica es
was used o es he s a is ical s eng h o he b anches.
The i le was con e ed in o New Hampshi e o ma wi h
NJBAFD ( TAKEZAKI 1998) and he ee was d awn wi h
T eeView e . 1.6.1 ( PAGE 2000). To desc ibe he le el o
0.2 U ( P l aL2, P l aL3, P l aL9, S i4, S i6, S iL7, S iL8
and S iL11 ) o 0.3 U ( S i33 ) o DyNAzyme II DNA
Polyme ase (Finnzymes, Espoo, Finland) and 15 – 25 ng
o genomic DNA.
PCR we e ca ied ou in a he mal cycle (MJ Resea ch)
and he empe a u e p o i le o he PCR p og am was a
94 ° C o 4 min, ollowed by 30 cycles a 94 ° C o 1 min,
he locus-speci i c annealing empe a u e o 1 min, elon-
ga ion a 72 ° C o 1 min, and a i nal elonga ion s ep a
72 ° C o 10 min. Locus-speci i c annealing empe a u es
we e 50 ° C o S i6 , 53 ° C o P l aL2, P l aL3, P l aL8,
S iL7, S iL8 and S iL11, 58 ° C o P l aL9 and S iL9 , and
60 ° C o S i4, S i18 and S i33 . An ABI 3130 Gene ic
Analyze was used o geno yping and allele sizes we e
de e mined wi h GeneMappe 4.0 so wa e (Applied
Biosys ems, ⬍ www3.appliedbiosys ems.com/AB_Home/
index.h m ⬎ ).
S a is ical analysis
The numbe s o alleles in samples we e compa ed
by a a e ac ion-based allelic ichness measu e (A
; EL
MOUSADIK and PETIT 1996; PETIT e al. 1998) ha was
calcula ed wi h FSTAT so wa e e . 2.9.3 ( GOUDET
2001). The p og am calcula es allelic ichness o he
smalles numbe o indi iduals yped o any locus, which
in he p esen s udy was 31 indi iduals o 11 loci (locus
S iL9 excluded). Allele equency a iances o e samples
we e es ima ed as G
s ( NEI 1973), and he e ozygosi y wi h
he aid o DISPAN so wa e ( OTA 1993).
Exac es s o he Ha dy – Weinbe g (H-W) equilib ium
( GUO and THOMPSON 1992) and popula ion di e en ia ion
Table 2 . Analyzed mic osa elli e loci. Type o epea sequence, numbe o obse ed alleles (N
a ), allele equency a iance
o e samples (N EI ’ s G s and F s ), o al he e ozygosi y (H
), and mean he e ozygosi y (H
s ) o each mic osa elli e locus and
mean F
s be ween coas al and lake popula ions o each locus in Finnish pikepe ch samples.
Locus Repea sequency Size N
a G
s F
s H
H
s
F
s coas al/
lake
1 P l aL2 (CA)
23 209 – 229 7 0.34 0.38 0.45 0.30 0.37
2 P l aL3 (TG)
18 101 – 119 8 0.15 0.15 0.34 0.29 0.18
3 P l aL8 (TG)
39 167 – 203 16 0.30 0.32 0.72 0.51 0.42
4 P l aL9 (TG)
24 182 – 214 4 0.20 0.22 0.65 0.52 0.31
5 S i4 (AC)
16 120 – 166 15 0.07 0.07 0.70 0.65 0.09
6 S i6 (AC)
6 115 – 165 19 0.18 0.19 0.61 0.50 0.27
7 S iL7 (TG)
22 201 – 249 17 0.12 0.13 0.64 0.56 0.15
8 S iL8 (TG)
22 107 – 145 8 0.40 0.30 0.34 0.20 0.11
9 S iL9 (CA)
18 AA(CA) 3 A(AC) 4 161 – 223 10 0.06 0.01 0.17 0.17 0.01
10 S iL11 (TG)
26 G(TG) 8 115 – 121 3 0.04 0.03 0.12 0.12 0.03
11 S i18 (AC)
18 132 – 182 10 0.11 0.12 0.67 0.59 0.11
12 S i33 (AC)
14 75 – 83 3 0.16 0.18 0.25 0.21 0.14
Mean allo e 10 0.19 0.18 0.47 0.38 0.18
Min 3 0.01 0.04 0.12 0.12 0.01
Max 19 0.38 0.40 0.72 0.65 0.42
He edi as 147 (2010) B ackish and eshwa e pikepe ch di e gene ically 209
in he e ozygosi y we e obse ed be ween he Lake
Vanaja esi sample and he coas al samples o Tai assalo
and V ä s an j ä d (p ⬍ 0.05). S a is ically signi i can
de ia ions in Ha dy – Weinbe g equilib ium occu ed in
h ee samples. In Painio sample he e was a de i ciency
o he e ozygo es (F
is ⫽ 0.03), and in coas al samples
Tai assalo (F
is ⫽ – 0.10) and V ä s an j ä d (F is ⫽ – 0.12)
excess o he e ozygo es, indica ing possibly subpopu-
la ion s uc u e in he Painio sample and mixing o
b eeding popula ions in he coas al samples.
The a e age mean he e ozygosi y o he coas al sam-
ples was lowe (0.34) han o he lake samples (0.42)
(Table 3), bu he di e ence was no signi i can . The
allelic ichness o coas al samples was on a e age lowe
(3.6) han ha o he lake samples (4.6). This di e ence
was also s a is ically signi i can (p ⬍ 0.01).
Gene ic di e en ia ion
Gene ic di e en ia ion was s a is ically highly signi i -
can be ween all o he pai s o samples excep o he
geog aphically close coas al popula ions o Tai assalo
and V ä s an j ä d. Acco ding o gene ic dis ances, he
samples g ouped in o wo main g oups: lake popula-
ions and coas al popula ions (Fig. 2). The a e age
gene ic dis ance be ween lake and coas al samples was
0.19, and he co esponding F
s was 0.25 and R
s as
high as 0.32 (Table 4). Gene ic dis ances wi hin hese
g oups we e smalle , he coas al popula ions in pa icu-
la o ming a homogeneous g oup wi h he a e age
dis ance among hem being only 0.07 and F
s 0.11 (R
s
only 0.03). R
s was highe han F
s , in all o he cases,
indica ing mu a ion possibly playing a ole behind he
popula ion s uc u e, which can be ega ded as sign o
polyphyle ic o igin. Acco ding o he pe mu a ion es
gene ic di e en ia ion in all popula ions and in he case
when only b ackish and eshwa e samples we e ea ed
sepa a ely a GeneClass sel -assignmen es was done
( CORNUET e al. 1999), wi h lea e-one-ou p ocedu e and
Bayesian op ion.
RESULTS
Amoun o gene ic di e si y
The amoun o gene ic di e si y was in gene al ela i ely
high. The numbe o alleles in he s udied loci a ied om
3 o 19, wi h an a e age o 10 alleles/locus (Table 2).
The di e si y o he loci a ied conside ably, wi h G
s
o e all samples being en imes highe o S iL8 (0.40)
han o S iL11 (0.04). G
s o e loci was abo e he mean
alue a ou loci: P l aL2, P l aL8, P l aL9 and S i8L . To al
di e si y (H
) among loci a ied be ween 0.12 ( S iL11 )
and 0.72 ( P l aL8 ). The di e en ia ion be ween coas al,
b ackish wa e and lake popula ion samples was clea es
a ou loci, P l aL2, P l aL8, P l aL9 and S i6 (Table 2),
om which P l aL2 and P l aL8 especially di e en ia ed
hese wo o ms.
The o e all mean he e ozygosi y (H
e ) o e loci and
samples was 0.39 and allelic ichness (A
) 5.3 (Table 3).
The mos a iable was he Lake Vanaja esi pikepe ch
sample, wi h a he e ozygosi y o 0.46 and a e age allelic
ichness o 5.5. This sou he n Lake Vanaja esi popula-
ion also had he highes numbe (9) o p i a e alleles
(alleles ha a e p esen in only one popula ion). The
leas a iable was he coas al Tai assalo sample, wi h
a mean he e ozygosi y o 0.30 and an a e age allelic
ichness o 3.3. S a is ically signi i can di e ences
Table 3 . Mean sample size o 12 loci, mean he e ozygosi y
(H e ), i s s anda d e o (SE), and a e age allelic ichness
based on 11 loci and 31 indi iduals (A
) o he s udied
Finnish pikepe ch popula ions.
Mean N H
e SE
A
/11
Loci
Coas al
1 Tai assalo 58.1 0.30 0.06 3.3
2 V ä s an j ä d 57.6 0.34 0.06 3.9
3 Vanhankaupunginlah i 55.6 0.37 0.07 3.4
Mean 0.34 3.6
Lake
4 Lake Lohjanj ä i 53.7 0.40 0.07 4.3
5 Lake A e ia 51.4 0.41 0.07 4.3
6 Lake Painio 68.8 0.36 0.08 4.2
7 Lake Vanajanselk ä 51.8 0.46 0.08 5.5
8 Lake Kemij ä i 56.3 0.45 0.06 4.0
Mean 0.42 4.6
O e all mean 0.39 5.3
0.1
Lake Kemijä i
Lake Vanajanselkä
Lake Painio
Lake Lohjanjä i
Lake A e ia
Vanhankaupunginlah i,
coas
Väs an jä d,
coas
Tai assalo,
coas
95
99
100
60
52
80
Fig. 2. Un oo ed ee o gene ic dis ances be ween he s ud-
ied Finnish pikepe ch popula ions based on 12 mic osa elli e
DNA loci.

210 M. Säisä e al. He edi as 147 (2010)
DISCUSSION
Di e ences be ween coas al and lake popula ions
The main i nding o his s udy was he ma ked gene ic
di e en ia ion be ween coas al and lacus ine pikepe ch
popula ions. In gene al, he lake popula ions showed
highe gene ic di e si y han he coas al ones. The h ee
coas al popula ions (Vanhankaupunginlah i, V ä s an j ä d
and Tai assalo) also g ouped igh ly oge he in e ms o
gene ic dis ance. The i e lake samples o med a loose
g oup, whe e he sole no he n popula ion in ou s udy
(Lake Kemij ä i) showed a g ea e dis ance om he o he
ou .
B J Ö RKLUND e al. (2007) ecen ly examined he gene ic
di e si y o pikepe ch popula ions wi hin abou he same
geog aphical a ea as we did (i.e. a ound no he n Bal ic
Sea), and he e a e many simila i ies be ween hei esul s
and ou s. Fo ins ance, he obse ed allele sizes we e qui e
simila in bo h s udies, and he o e all le el o gene ic
di e si y was also abou he same. The mos impo an
i nding o BJ Ö RKLUND e al. (2007) was he a iabili y o
he popula ions along he no h-sou h axis, wi h he no h-
e n popula ions being in gene al mo e di e se han he
sou he n ones. Howe e , he au ho s did no speci i cally
men ion he di e ence be ween lake and coas al popula-
ions, which we conside c ucial om bo h scien i i c and
managemen pe spec i es. Ne e heless, in hei da a he
lake popula ions also had a highe allelic ichness (a e -
age 4.7 alleles) and gene ic di e si y (0.55) han he
coas al popula ions (3.5 alleles and 0.50).
The obse ed di e en ia ion le el be ween pikepe ch
eco ypes is highe han ha o conspeci i c i sh popula-
ions on a e age. The F
s o 0.25 is e y high compa ed
o he F
s among anad omous and eshwa e whi e i sh
ypes ( Co egonus la a e us ), he mean o which was
epo ed o be only 0.03 and 0.42 o wo species, Co e-
gonus peled and C. la a e us , in a i e-loci mic osa el-
li e da a se ( S Ä IS Ä e al. 2008). I is also high when
compa ed o he gene ic di e si y among A lan ic salmon
o allele sizes, s a is ically signi i can di e ence could
be obse ed o all popula ions (P ⫽ 0.04). On a e age,
in oduced popula ions om Lakes Painio and A e ia
had a low F
s (0.03) and small gene ic dis ance (0.06)
om hei likely sou ce popula ion o Lake Lohjanj ä i
and also om each o he . The smalles F
s and gene ic
dis ance wi hin he lake samples was obse ed be ween
Lake Lohjanj ä i and Lake Painio (0.01 and 0.05 espec-
i ely; Table 5).
All he sou he n lake popula ions we e ela i ely
simila , wi h an a e age dis ance o 0.08 and F
s 0.06,
bu he sample o no he nmos lake popula ion (Lake
Kemij ä i) di e ed s ongly om he sou he n lake
popula ions, wi h F
s 0.19 and a D
A dis ance o 0.22.
In gene al i was s ill mo e simila o lake han coas al
popula ions (Table 5). In he dend og amme, all he
boo s ap alues we e o e 50% and he dis inc ion
be ween lake and coas al samples had 100% boo s ap
suppo (Fig. 2). I he h ee mos a iable loci, P l aL2,
P l aL8 and S iL8, we e excluded om he dis ance
analysis he g ouping in o wo main g oups emained he
same and he g ouping p obabili y was s ill as high
as 97%. When he GeneClass sel -assignmen es was
done o all popula ions, he pe cen age o co ec assign-
men was 72.93%, bu when only coas al and lake popu-
la ions we e conside ed sepa a ely, as many as 98.59%
o he indi iduals we e co ec ly assigned o i s sou ce o
o igin, ei he lake o coas .
Table 4 . F
s and R s es ima es and D
A dis ances o Finnish
pikepe ch popula ion g oups.
G oups F
s R
s D
A
Be ween coas and lakes 0.25 0.32 0.19
wi hin coas 0.11 0.03 0.07
wi hin lakes 0.11 0.16 0.15
Be ween no he n and sou he n lakes 0.19 0.26 0.22
wi hin sou he n lakes 0.06 0.09 0.08
Table 5 . Es ima es o D
A dis ances (abo e diagonal) and F
s alues (below diagonal) be ween pai s o Finnish pikepe ch
popula ions.
Tai assalo V ä s an j ä d Vanhankaupunginlah i
Lake
Lohjanj ä i
Lake
A e ia
Lake
Painio
Lake
Vanajanselk ä
Lake
Kemij ä i
Tai assalo * 0.02 0.10 0.20 0.20 0.17 0.18 0.25
V ä s an j ä d 0.01 * 0.09 0.19 0.19 0.15 0.16 0.25
Vanhankaupunginlah i 0.17 0.13 * 0.17 0.18 0.16 0.17 0.28
Lake Lohjanj ä i 0.30 0.27 0.20 * 0.05 0.06 0.11 0.20
Lake A e ia 0.30 0.27 0.22 0.01 * 0.07 0.11 0.22
Lake Painio 0.29 0.25 0.20 0.04 0.03 * 0.09 0.21
Lake Vanajanselk ä 0.22 0.19 0.17 0.09 0.09 0.09 * 0.24
Lake Kemij ä i 0.30 0.27 0.25 0.18 0.16 0.21 0.19 *
He edi as 147 (2010) B ackish and eshwa e pikepe ch di e gene ically 211
pos glacial coloniza ion his o y. The habi a equi emen s
o pikepe ch a e simila o i s ela i e, he pe ch ( Pe ca
l u ia ilis ). As hese wo pe cids a e basically eshwa e
species, bu ole a e b ackish wa e , i is likely ha hei
pos glacial coloniza ion ou es ha e been a leas pa ly
he same. Mos eshwa e species ha e e-colonised
Scandina ia om some o he la ge e uge lakes o lake
a eas, in o which hey we e o ced o wi hd aw du ing he
glacia ions ( HEWITT 1999). Th eespined s ickleback has
p obably been an excep ion om his as i mo e eadily
spawns e en in ma ine en i onmen ( M Ä KINEN e al.
2006). A leas ou po en ial e ugia ha e been p oposed
o eshwa e i shes ( NESB Ø e al. 1999), and he Bal ic
Sea d ainages ha e been assumed and ound o be a
con ac zone in he eas e n and wes e n dis ibu ion o
se e al species, such as A lan ic salmon ( Salmo sala )
( KOLJONEN e al. 1999; S Ä IS Ä e al. 2005), b own ou
( GARC Í A-MAR Í N e al. 1999), g ayling ( Thymallus hy-
mallys ) ( KOSKINEN e al. 2000) and bullhead ( Co us
gobio ) ( KONTULA and V Ä IN Ö L Ä 2001).
The ou e ugia p oposed as sou ces o con empo a y
pe ch popula ions a e: he Danubian a ea (1), he Black
Sea (2), wes e n Eu ope (3), and eas e n Eu ope (4), wi h
he Danubian popula ion being he oldes . Howe e , he
pe ch popula ions in Fennoscandia p obably only o igi-
na e om he h ee la e e ugia (2 – 4; NESB Ø e al. 1999).
When he na i e dis ibu ion a ea o pikepe ch is com-
pa ed o he p oposed coloniza ion ou es o pe ch, i
seems possible ha pikepe ch ini ially colonized he Bal-
ic Sea d ainage a ea om only he wo eas e n e ugia,
i.e. om eas e n Eu ope and he Black Sea a ea. I his is
ac ually he case, hese wo phylogene ic lineages may
s ill unde lie he p esen gene ic di e si y in Scandina ian
pikepe ch, po en ially including he obse ed di e ences
be ween he coas al and lake popula ions.
In addi ion o he ini ial pos -glacial e-coloniza ion
ha po en ially al eady occu ed du ing he i s Bal ic
Sea s age, he Bal ic Ice Lake (abou 15 000 – 11 600 BP;
M YRBERG e al. 2006), he unde lying di e ences in he
gene ic cons i u ion o he coas al and lake popula ions
may also ela e o he la e s ages o he Bal ic Sea wi h
hei di e en salini ies, empe a u es and wa e le els.
Ins ead o he ela i ely cold Bal ic Ice Lake, o he saline
Yoldia Sea (abou 11 600 – 10 800 BP), he o iginal dis-
ibu ion o pikepe ch in no he n Eu ope has been sug-
ges ed o be ela ed o he Lake Ancylus ( eshwa e ) s age
( LEHTONEN e al. 1996), which appa en ly p o ided he
species a a o able habi a om 10 800 o 9 000 BP and a
dis ibu ion channel o a eas co e ed by he o me lake,
i.e. up o 100 – 150 me e s abo e he p esen wa e le el
o he Bal ic Sea. The his o y o he coas al dis ibu ion
may, howe e , be sho e , due o he high salini y (up o
20 psu) o he nex s age o he Bal ic Sea, he Li o ina Sea
(8000 – 4000 BP), which p obably limi ed he a o able
( Salmo sala ) popula ions, which simila ly a e depended
on eshwa e in hei ep oduc ion, and o which
he polyphyle ic o igin is obse ed. The o e all F
s o
all s udied Eu opean popula ions was 0.14 a 9 mic o-
sa elli e loci ( S Ä IS Ä e al. 2005). The F
s o all Bal ic
Sea d ainage popula ions, including h ee coloniza ion
lineages, was 0.11. In he da a o BJ Ö RKLUND e al. (2007)
he mean F
s o pikepe ch popula ions was 0.17. The
high R
s alues also suppo he hypo hesis o polyphyl-
e ic o igin. A s ong gene ic s uc u ing is e iden in
pikepe ch popula ions om he Bal ic Sea a ea, ei he as
esul o selec i e o ces o long- e m isola ion pa e ns
ela ed o coloniza ion his o ies.
The no he n Lake Kemij ä i was also sampled in he
s udy o BJ Ö RKLUND e al. (2007), and hence o e s an
in e es ing oppo uni y o a close compa ison o he wo
s udies. The di e si y le els obse ed o Lake Kemij ä i
by BJ Ö RKLUND e al. (2007), measu ed ei he as allelic
ichness (4.2/4.0) o as gene di e si y (0.48/0.46), we e in
good acco dance wi h ou own obse a ions ( alues om
B J Ö RKLUND e al. and ou s udy, espec i ely). Howe e , in
con as o BJ Ö RKLUND e al. (2007), he Lake Kemij ä i
popula ion was in he p esen s udy no mo e di e se han
he o he ou (sou he n) lake popula ions. This migh
indica e a highe gene ic di e si y in Finnish, mo e eas -
e n, han Swedish pikepe ch popula ions.
Fac o s a ec ing di e en ia ion
The po en ial mechanisms behind he obse ed gene ic
di e en ia ion o pikepe ch popula ions include pos gla-
cial coloniza ion his o y, gene l ow and gene ic d i . The
a ia ion in neu al ma ke s is usually no assumed o be
di ec ly linked o po en ial local adap a ions, i.e. he abil-
i y o he popula ions o cope wi h hei speci i c biological
and physical en i onmen . In his espec , he obse ed
di e en ia ion be ween he sea and eshwa e o ms o
pikepe ch was somewha su p ising, as in o he species
he eco ypic di e ences ha e no usually been e l ec ed in
he gene ic dis ances o neu al ma ke s. In b own ou
( Salmo u a ), o example, he mos impo an di e en-
ia ing ac o is he i e sys em, ollowed by he di e -
ence be ween ma ine and eshwa e eco ypes ( RYMAN
1983). In ou s udy, some o he loci showed especially
high di e gence simply be ween popula ions o di e en
en i onmen s, such as P l a2 (F s 0.37) and P l a8 (F s 0.42),
possibly indica ing some connec ion o adap i ely impo -
an genes. Howe e , he coloniza ion his o y and mig a-
ion pa e n o b own ou and pikepe ch a e assumed
o di e ma kedly. Mig a ion and gene l ow be ween
eshwa e and ma ine o ms o b own ou is also mo e
cons an han be ween pikepe ch eco ypes.
The di e ences be ween he eshwa e and coas al
popula ions may also s em om hei di e en ini ial
212 M. Säisä e al. He edi as 147 (2010)
his case al eady in he i s hal o he 20 h cen u y.
These wo popula ions we e selec ed because hey ha e
been - and s ill a e - among he mos common ha che y
popula ions in Finland, and hence sou ces o pas and
u u e human-induced gene l ow, no only in eshwa e
sys ems bu also in po en ially inc easing u u e eleases
in coas al a eas.
The pikepe ch popula ions o Lakes Painio and A e ia
g ouped close o hei likely sou ce popula ion o Lake
Lohjanj ä i and, somewha su p isingly, hei di e si y
le el was nea ly he same. This sugges s ha a leas in
hese wo cases he old p ac ice o in oducing pikepe ch
o new wa e bodies by se e al eplica e ans e s o adul
indi iduals and/o e ilized eggs has no c ea ed a signi i -
can bo leneck, and also ha he ec ui men has been
con inuously s ong enough o main ain he o iginally
ans e ed di e si y. S ong and s able ec ui men is also
he eason o hei p esen use as sou ce popula ions o
ha che y p oduc ion.
Managemen implica ions
Sa egua ding he gene ically unique Bal ic coas al pike-
pe ch popula ions om gene l ow om he looming ha ch-
e y eleases using lake pikepe ch should be a high
managemen p io i y a all le els o decision making. This
is especially impo an aking in o accoun he ecological
change in he ma ine en i onmen ha is con inuously
challenging he ecological adap abili y o all o ganisms
li ing in he Bal ic Sea (see HELCOM Bal ic Sea Ac ion
Plan, ⬍ www.helcom. i ⬎ ). Fac o s such as con inuing
eu ophica ion and pollu ion, in asi e species, dec easing
salini y and inc easing i shing p essu es may all ma kedly
in l uence u u e ec ui men and habi a condi ions o
pikepe ch in he coas al a eas o he Bal ic Sea. In his
si ua ion, he po en ially e y high en i onmen al s ess
on he species ’ adap i e po en ial should no be in en ion-
ally inc eased by haphaza dly in oducing o eign genes
o he popula ions. The applica ion o he p ecau iona y
app oach would imply ha ins ead o eleases ha may
lead o mal-adap a ion and educ ion o he iabili y o he
cos al pikepe ch popula ions, p io i y should be gi en o
mo e sus ainable long- e m managemen app oaches,
especially o sound egula ion o he i she ies.
The wo p incipal sou ce popula ions (Lakes A e ia
and Painio) o ecen Finnish ha che y p oduc ion o
pikepe ch ju eniles appea ed gene ically su p isingly
di e se, aking in o accoun hei backg ound as human-
in oduced popula ions. Despi e his ac , hei ex ensi e
and con inuous use as all- ound popula ions in mul iple
eleases in eshwa e sys ems all o e he coun y is
ques ionable and h ea ens he s ill exis ing gene ic
di e si y and po en ial local adap a ions o he species.
The long gene ic dis ance be ween he no he nmos (Lake
habi a o pikepe ch in coas al a eas. Salini ies o e 5 psu
inc ease he mo ali y o pikepe ch eggs and ea ly la ae
( WINKLER e al. 1989), al hough adul pikepe ch ole a e
exposu e o g adually ising salini y peaking a 29 – 33 psu
( BROWN e al. 2001). The salini y o he p esen Bal ic Sea
a ies om 2 psu in he no h o 20 psu in he sou h.
As he geog aphical dis ibu ion o ou sampling was
limi ed, no i nal conclusion can ye be d awn abou he
coloniza ion lineages o pikepe ch in ou wa e s. Mo e
ex ensi e sampling o pikepe ch popula ions h oughou
he Fennoscandian dis ibu ion o he species should be
o ganized. The signi i can di e en ia ion be ween he
eshwa e and b ackish wa e popula ions, howe e , indi-
ca es a deepe gene ic clea age han simply pos glacial
popula ion di e en ia ion.
Gene l ow be ween popula ions may be media ed by
na u al mechanisms (mig a ions om one wa e body o
ano he ) o by man. In he case o Fennoscandian, and
especially Finnish pikepe ch popula ions, human-induced
gene l ow h ough ea ly in oduc ions and la e enhance-
men and e-s ocking ac i i ies should no be unde es i-
ma ed. The his o y o popula ion ans e s is o e 100
yea s long ( HALME 1961, 1962), and du ing he la es
boom in enhancemen and e-s ocking p og ams, only a
ew o he o iginal eshwa e popula ions o pikepe ch
ha e p obably emained o ally in ac om human-induced
gene l ow om o he popula ions. Acco ding o he cu -
en s ock egis y da abase o he Finnish Game and Fish-
e ies Resea ch Ins i u e, only 7% o a o al o 880 epo ed
si es o pikepe ch occu ence could be ega ded as indig-
enous. All o he popula ions a e known o ha e been a -
ge s o supplemen a y ju enile eleases o a e he esul o
popula ion in oduc ions (Fig. 1). Indigenous popula ions
mainly emain in he eas e n and coas al a eas.
Du ing he las 25 yea s in many wa e bodies, massi e
and con inuing eleases o pond- ea ed 1-summe -old
ju enile pikepe ch ( o alling 5 – 10 million indi iduals pe
yea ; ANONYMOUS 2001) ha e p obably ma kedly in l u-
enced he gene ic di e si y o he species. Taking in o
accoun he usually e y small numbe o sou ce popula-
ions, he limi ed numbe o b eede s and he p ac ices o
p oducing e y la ge quan i ies o indi iduals pe amily,
he likely di ec ion o his change has been om a highe
o iginal o a educed p esen species le el di e si y.
When selec ing pikepe ch popula ions o ou s udy we
used all a ailable knowledge on managemen ac ions
( HALME 1961, 1962; TOIVONEN e al. 1981; LEHTONEN e al.
1984) o a oid he in l uence o ecen gene l ow om
ha che y eleases on ou esul s. The e o e, his o ical sam-
ples we e used in some o he cases (Lakes Lohjanj ä i and
Vanajanselk ä ). Howe e , in addi ion o six indigenous
popula ions ( h ee coas al, h ee eshwa e ) we also sam-
pled wo popula ions (Lakes Painio and A e ia) ha we e
o iginally es ablished h ough in oduc ions, al hough in
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Finland. – Aqua Fenn. 14: 189 – 196.
Leh onen, H., Hansson, S. and Winkle , H. 1996. Biology and
exploi a ion o pikepe ch, S izos edion luciope ca (L.), in
he Bal ic Sea a ea. – Ann. Zool. Fenn. 33: 525 – 535.
Kemij ä i) and he o he lake popula ions sugges s ha
long ans e s om he sou h o he no h, o ice e sa,
should pa icula ly be a oided. I suppo i e eleases
appea absolu ely necessa y in some special ci cum-
s ances, local indigenous popula ions should be p e e ed
as sou ce popula ions and ea ing should gene ally aim
a p oducing ju eniles om a la ge numbe o b eede s
wi h a lowe numbe o indi iduals pe amily.
De ailed knowledge o he a iabili y and popula ion
s uc u e o exploi ed i sh popula ions is a p e equisi e o
hei sus ainable long- e m managemen . In he case o he
pikepe ch popula ions, he analysis o 12 mic osa elli e
loci appea ed o be able o p oduce in aluable new in o -
ma ion on hei pas and p esen gene ic a iabili y and
di e ences be ween popula ions. E en om he oldes
samples o his s udy ( om he ea ly 1980s) i was possi-
ble o ge DNA- esul s o he analysis. The possibili y o
ex ac ing he DNA om ca ch (scale) samples o iginally
collec ed o o he pu poses imp o ed he cos -e ec i e-
ness o he analysis.
In his s udy we in es iga ed he indigenous gene ic
di e si y o pikepe ch popula ions, which in he case o
mos Finnish eshwa e sys ems has al eady been los
because o he appa en ly unlimi ed ai h in he bene i s
o ha che y eleases among local manage s and wa e
owne s. Much mo e esea ch and communica ion is
clea ly needed i he old managemen p inciples a e o
be changed. The nex s ep owa ds mo e sus ainable
managemen could be he mapping and he ea e s ic
p o ec ion o he emaining gene ically in ac indigenous
eshwa e popula ions. I would also be c ucial o know
how he mos hea ily s ocked indigenous pikepe ch
popula ions ha e adap ed o he p essu e om he
con inuous l ow o o eign genes: wha is le o hei
o iginal gene ic s uc u e?
Acknowledgemen s - We hank Jukka Kummunsalo and Olli
Pii oinen o p o iding pikepe ch samples om Lakes Painio
and Vanajanselk ä , espec i ely. All samples we e aged by Ka l
Sundman.
REFERENCES
Anonymous 2001. Finnish i she y ime se ies. Finnish o i cial
s a is ics. Aquacul u e, o es y and Fishe y 2001, 60.
Bo e , S. O., Mille , L. M. and Kapuscinski, A. R. 1999.
Mic osa elli es in walleye S izos edion i eum . – Mol. Ecol.
8: 335 – 346.
Bj ö klund, M., Aho, T. and La sson, C. 2007. Gene ic
di e en ia ion in pikepe ch ( Sande luciope ca) : he ela i e
impo ance o gene l ow, d i and common his o y. – J. Fish
Biol. 71 suppl. B: 264 – 278.
B own, J. A., Moo e, W. M. and Quabius, E. S. 2001.
Physiological e ec s o saline wa e s on zande . – J. Fish
Biol. 59: 1544 – 1555.