209
In eg a ing social media and en i onmen al DNA eco ds
o enhance su eillance and imp o e ea ly de ec ion o
in asi e species
Diogo Dias1,2 , So ia Ba is a1, So ia Noguei a1, Manuel Cu o3,4 , Diogo Ribei o1, Rui Ri aes1,
Filipe Ribei o1
1 MARE, Ma ine and En i onmen al Sciences Cen e / ARNET, Aqua ic Resea ch Ne wo k, Facul y o Sciences, Uni e si y o Lisbon, 1749-016 Lisbon, Po ugal
2 CE3C - cE3c – Cen e o Ecology, E olu ion and En i onmen al Changes/Global Change and Sus ainabili y Ins i u e, Facul y o Sciences, Uni e si y o Lisbon,
1749-016 Lisbon, Po ugal
3 CIBIO – Resea ch Cen e in Biodi e si y and Gene ic Resou ces, InBIO Labo a ó io Associado, Campus de Vai ão, 4485-661 Vai ão, Po ugal
4 BIOPOLIS – P og am in Genomics, Biodi e si y and Land Planning, Campus de Vai ão, 4485-661 Vai ão, Po ugal
Co esponding au ho : Diogo Dias ([email p o ec ed])
Copy igh : © Diogo Dias e al.
This is an open access a icle dis ibu ed unde
e ms o he C ea i e Commons A ibu ion
License (A ibu ion 4.0 In e na ional – CC BY 4.0).
Resea ch A icle
Abs ac
The ea ly de ec ion o in asi e species in aqua ic ecosys ems is pa icula ly challenging wi h mos
eco ds o new species made yea s a e hei ini ial in asion, by which ime hey a e al eady
widesp ead. Recen ly, ea ly de ec ion ools such as ci izen science and en i onmen al DNA ha e
eme ged, signi ican ly imp o ing ea ly wa nings in aqua ic ecosys ems. Howe e , he e is limi ed
unde s anding o how hese new ools complemen each o he and how consis en hey a e. In
his s udy, we p esen a case s udy combining social media da a mining and en i onmen al DNA
(eDNA) o de ec new eco ds o he in asi e Eu opean pe ch (Pe ca lu ia ilis) in mainland Po u-
gal. F om 2021 o 2024, we analyzed online angling g oups o iden i y po en ial new a eas o in a-
sion. La e , wa e samples we e collec ed om se e al ese oi s and es ed o he Eu opean pe ch
p esence using eal- ime quan i a i e PCR. This combined app oach de ec ed ou new loca ions
o Eu opean pe ch. Mo eo e , eDNA analysis e ealed h ee new po en ial popula ions, while
da a mining appea s o o e nea eal- ime acking o he species’ sp ead. This wo k showcases
he imp o ed e iciency and ea ly de ec ion bene i s o his in eg a ed app oach o moni o ing
eshwa e in asi e ish, wi h b oade applicabili y o o he in asi e species.
Key wo ds: Da a mining, de ec ion lag, Eu opean Pe ch, eshwa e s, non-na i e species, Pe ca
lu ia ilis, qPCR
In oduc ion
Biological in asions a e a global h ea o biodi e si y and ecosys em in eg i y, wi h
ad e se economic and socie al impac s (Lawle e al. 2006; Lodge e al. 2006; Eh-
en eld 2010; B adshaw e al. 2016). Fu he mo e, biological in asions and hei
impac s a e expec ed o con inue o ise on pa wi h cu en ends o global ade,
a el and anspo (IPBES 2023). The ideal app oach o mi iga e he impac o
in asi e species is o p e en hei in oduc ion in o new a eas (Lodge e al. 2006;
Finno e al. 2007). Following he in oduc ion o in asi e species, he e is only
Academic edi o : Paula Pappala do
Recei ed:
28 Feb ua y 2025
Accep ed:
9 July 2025
Published:
7 Oc obe 2025
Ci a ion: Dias D, Ba is a S, Noguei a S,
Cu o M, Ribei o D, Ri aes R, Ribei o
F (2025) In eg a ing social media
and en i onmen al DNA eco ds o
enhance su eillance and imp o e
ea ly de ec ion o in asi e species.
In: Anas ácio P, Ribei o F, Chainho P
(Eds) In asions in Aqua ic Sys ems.
NeoBio a 102: 209–226. h ps://doi.
o g/10.3897/neobio a.102.151710
NeoBio a 102: 209–226 (2025)
DOI: 10.3897/neobio a.102.151710
Ad ancing esea ch on alien species and biological in asions
A pee - e iewed open-access jou nal
NeoBio a
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NeoBio a 102: 209–226 (2025), DOI: 10.3897/neobio a.102.151710
Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
a b ie window du ing which e adica ion o con ol measu es a e bo h e ec i e
and cos -e icien (Ma inez e al. 2020). These ac ions a e highly dependen on
ea ly de ec ion o in asi e species, which plays a c i ical ole in enabling as e-
sponse measu es, and is iden i ied as a op p io i y in in asi e species managemen
p og ams (e.g., Vande Zanden e al. 2010; IPBES 2023). Ea ly de ec ion con-
s i u es a challenge pa icula ly in aqua ic ecosys ems, whe e new in oduc ions
emain hidden benea h he su ace, o en going unde ec ed o ex ended pe iods o
ime and, consequen ly, enabling hei es ablishmen and sp ead (McDonald and
Thompson 2004; Je de e al. 2011).
T adi ional de ec ion me hods, elying on he physical cap u e o specimens, a e
o en labo -in ensi e, ime-consuming and expensi e, leading o a lack o b oad geo-
g aphical and empo al co e age (Amano e al. 2016). Consequen ly, he e is a g ow-
ing demand o inno a i e su eying app oaches ha add ess hese weaknesses while
also enabling he ea ly de ec ion o in asi e species in eshwa e ecosys ems (Da -
ling and Mahon 2011). A ecen new ool is based on he eco e y o en i onmen-
al DNA (eDNA), i.e., he ma e ial ha o ganisms elease in o hei su oundings
h ough p ocesses such as shedding skin cells, sec e ing mucus, o eleasing game es
(Tabe le e al. 2012; Pawlowski e al. 2020). These me hods a e highly sensi i e,
making hem especially sui ed o de ec ing ea ly signs o in asi e species (Ca im e
al. 2019; Dua e e al. 2023) o assessing he success o e adica ion ac ions (Da ison
e al. 2019). Addi ionally, hei e iciency and cos -e ec i eness g ea ly enhance he
iabili y o la ge-scale moni o ing p og ams (Coble e al. 2019). These app oaches
can a ge speci ic axa using me hods like qPCR o use high- h oughpu sequencing
o cha ac e ize biological communi ies (Tabe le e al. 2012).
The use o eDNA in ea ly de ec ion o in asi e species may be pa icula ly ad an a-
geous when in eg a ed wi h o he echniques such as social media da a mining, which
can iden i y a eas o po en ial conce n and guide a ge ed eDNA sampling e o s (Pa -
ondo e al. 2018). In he digi al e a, a ising numbe o ec ea ional angle s u n o
in e ne o ums and social ne wo ks o sha e hei expe iences and connec wi h people
wi h simila in e es s (Gio os e al. 2018). Indi iduals o en upload ex , pho og aphs
and ideos ela ing o hei ishing ac i i y o social media, con en s ha a e aluable
o ishe ies sciences (Vi ale e al. 2021; Lennox e al. 2022). Gi en he key ole o an-
gle s in he sp ead o in asi e ish species, pa icula ly in he Ibe ian Peninsula (Ribei o
e al. 2009; Banha and Anas ácio 2015; Banha e al. 2024), his g owing sou ce o
in o ma ion may ep esen a cos -e ec i e sou ce o new eco ds ha can be used o
ack he spa ial occu ence o new in asi e ishes (Gago e al. 2016; Banha e al. 2017).
These da a ha e he po en ial, no only o complemen al eady exis ing in asi e spe-
cies moni o ing p og ams and me hodologies wi h ew added esou ces and expenses
(Daume 2016; Gago e al. 2016; Allain 2019), bu also o wo k as a sen inel ool o a
p omp no ice o new in oduc ions, and e o edi ec ion.
In Ibe ia, eshwa e ish a e among he mos h ea ened axonomic g oup (Cos-
a e al. 2021), wi h in asi e species widely ecognized as a majo h ea (He mo-
so and Cla e o 2011; Zamo a-Ma ín e al. 2023). Howe e , mos ecen Ibe ian
s udies on eshwa e ish in asions ha e p ima ily ocused on h ee aspec s: e-
po ing i s occu ences (Ribei o and Ve íssimo 2014; Banha e al. 2015), as-
sessing hei impac s on na i e auna (Ribei o e al. 2021; Gkenas e al. 2022), o
mapping hei dis ibu ion long a e es ablishmen (Banha e al. 2017; Ma elo
e al. 2021). In ac , he e is s ill limi ed in o ma ion abou he ange expansion
o ecen ly a i ed in asi e ish (bu see Gago e al. 2016), making i di icul o
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Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
iden i y seconda y in oduc ions by angle s wi hin speci ic egions, limi ing e ec-
i e ac ions o p e en u he sp ead (Ca ey e al. 2014).
Po uguese eshwa e s ha e been highly in aded by di e en axa (Anas ácio e
al. 2019; Zamo a-Ma ín e al. 2023), wi h one new ish species in oduced app ox-
ima ely e e y wo yea s o e he pas wo decades (Ribei o e al. 2009; Banha e
al. 2017). O hese, one o he mos ecen ly in oduced p eda o s is he Eu opean
pe ch (Pe ca lu ia ilis Linnaeus, 1758). This species was in oduced in 1898 in he
Azo es A chipelago by he Fo es y Se ices o p omo e angling ac i i ies (Goubie
e al. 1983; Ribei o e al. 2009). Howe e , i was i s de ec ed on he mainland
in 2013 (Banha e al. 2015). This species is na i e o pa s o Asia and Eu ope bu
na u ally absen in sou he n Eu opean Peninsulas (S epien e al. 2015). Due o i s
ec ea ional popula i y, i has been in oduced in many o he egions o Eu ope
(I aly, Spain and Cyp us), A ica (Mo occo and Sou h A ica), Asia (China) and
Oceania (Aus alia and New Zealand) (S epien e al. 2015; Ning e al. 2025) wi h
documen ed nega i e impac s on hese aqua ic ecosys ems (Mo gan e al. 2002;
Mo gan e al. 2004). This s udy aimed o assess whe he social media eco ds o
Eu opean pe ch could help guide an eDNA-based moni o ing campaign a ge ing
his in asi e ish and moni o i s ange expansion ac oss mainland Po ugal. Using
a ecen ly in oduced ish in Po ugal as a case s udy, we sough o show he po-
en ial o in eg a ing species eco ds om social media da a mining, eDNA-based
moni o ing, and scien i ic ishing o e alua e he complemen a i y be ween hese
app oaches and iden i y in asion ou es and seconda y in oduc ion loca ions.
Me hods
S udy a ea
In 2013, he Eu opean pe ch was con i med on mainland Po ugal o he i s
ime, in a small ese oi in P oença-a-No a (Indus ial Pa k o P oença-a-No a -
PEPA, 39°43'19.9"N, 7°53'58.6"W), loca ed in he cen al egion o he coun y
(Banha e al. 2015). This emained he only known in oduc ion si e un il 2021,
when a new popula ion was eco ded in a la ge ese oi in Sabugal (40°19'57.8"N,
7°05'27.9"W), si ua ed in a di e en d ainage basin (Fig. 1A).
Da a mining
We collec ed in o ma ion on angle s’ ca ches o Eu opean pe ch om publicly a ailable
social media pos s on Facebook™, a popula pla o m among angle s in Po ugal wi h
he la ges eshwa e angling g oup hos ing o e 30,000 membe s, and YouTube™.
On bo h social media websi es, po en ially ele an pos s we e iden i ied by
using he sea ch ool wi h selec ed key-wo ds. Sea ch keywo ds included he spe-
cies’ common name in Po uguese (“pe ca eu opeia”) and a ian s, such as “pe ca”,
“pe cilha” and “pe che”. Addi ionally on Facebook, sea ches wi hin ishing-g oups,
such as “Pesca em Água Doce” and “Big Pe ch Mons e ” we e conduc ed o iden-
i y pos s ela ed o he a ge species, as hese g oups ha bo la ge and engaged
communi ies on Po uguese and pe ch angling, espec i ely. The da ase included
pos s since May 2021, when he i s eco d o Eu opean pe ch appea ed on Face-
book™, un il Decembe 2024. All collec ed pos s we e manually e iewed o con-
i m species iden i ica ion, cap u e loca ion and da e, while he aw da a was used
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Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
o analyze publica ion ends h ough ime. Then, only pos s explici ly ela ed o
ec ea ional ishing o Eu opean pe ch, i.e., ideos o pho og aphs o ca ches o
pe ch we e selec ed o u he analysis. Fo each pos , we ex ac ed in o ma ion
on he ca ch’s da e and loca ion, and compiled da a om he di e en sou ces in o
one inal da ase . The da a collec ion p ocess adhe ed o e hical guidelines o so-
cial media use in ishe ies esea ch, ensu ing no pe sonal in o ma ion was eco ded
and no o iginal use con en was sha ed publicly (Monkman e al. 2018).
Fish sampling
To con i m he p esence o suspec ed Eu opean pe ch popula ions epo ed on
social media, ield sampling was conduc ed in suspec ed loca ions in Feb ua y
2023. Gillne s ollowing he Eu opean s anda d EN 14 757 (CEN 2005) we e
deployed and le o e nigh . Subsequen o hese esul s, nea by s eams we e
sampled using elec o ishing equipmen (Hans G assl EL 6 2 gene a o , DC,
600 V) o e alua e po en ial pe ch dispe sal beyond he ese oi s. Elec o ishing
was conduc ed along a 120-me e s e ch o he s eam using a zigzag wading
pa e n. All cap u ed ish’ o al leng h was measu ed. Na i e species we e e-
leased, while in asi e species we e eu hanized in compliance wi h local egula-
ions using a clo e oil o e dose as an anes he ic. The p esence o Eu opean pe ch
was con i med by he cap u e o a leas one indi idual.
En i onmen al DNA samples collec ion
Si e selec ion o eDNA analysis was in o med by a combina ion o social media
da a mining and species dis ibu ion eco ds (Fig. 1A, B). Sampling was con-
duc ed on ese oi s wi h known popula ions o Eu opean pe ch as posi i e con-
ols, such as Sabugal and PEPA. Nea by and hyd ologically connec ed ese oi s
we e sampled o p ospec he exis ence o unde ec ed popula ions. The sampling
e o was de e mined based on wa e body size: one il a ion si e in small ese -
oi s (<15 ha), wo in medium (15–150 ha) and i e in la ge ese oi s (>150 ha)
o i e s. Si es wi hin each ese oi we e selec ed o be as widely dispe sed as
possible o maximize de ec ion p obabili y.
Be ween he 24 h o June and he 24 h o July o 2023, eDNA samples we e
collec ed a 52 si es ac oss he hyd og aphic basins o he Tagus (32 si es), Dou-
o (13 si es), and A e (7 si es) (Fig. 1C). A each si e, we il e ed 30 l o wa e
h ough a 0.45 μm po e-size il e (GoP oTM High Capaci y G oundwa e Fil e ,
P oac i e, Flo ida, USA) connec ed by a plas ic hose o a diaph agm wa e pump
(A galy, Sain e-Helene Du Lac, F ance) wi h a lowme e a ached o he pump
ou le o moni o he il e ed olume. Ou a ge il a ion olume (30 l) was se
o maximize species de ec ion, as ecommended by Can e a e al. (2019). The
il a ion p ocess was s opped ea ly in he case o il e clogging, which we de-
ined as when he low a e d opped below 1 l pe 5 min. Upon comple ing he
il a ion, we loaded 50 ml o p ese a ion bu e (Longmi e e al. 1997) in o he
il e capsule and kep samples a 4 °C un il labo a o y analysis.
Field campaigns adhe ed o s ic con amina ion con ol measu es: he hose
connec ing he il e capsule o he inle o he pump was decon amina ed p io
o use and disca ded a e wa ds; he sy inge used o loading he bu e was sin-
gle-use; each il e capsule was capped, labeled and sealed indi idually inside a
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Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
decon amina ed zipped plas ic bag; wade s used du ing sampling we e decon am-
ina ed be ween si es; glo es we e wo n a all imes and exchanged be ween si es o
as needed wi hin he same si e. Decon amina ion consis ed o soaking he ma e ial
in a solu ion o 20% ( / ) comme cial bleach o a leas 30 min (40% bleach o
boo s). Field blanks we e p ocessed by il e ing 6 l o bo led wa e a he i s si e
each day (one blank pe day), ollowing he same p o ocol as egula samples. A
en al ca was used, ins ead o a esea ch ins i u e ca , o a oid con amina ion om
p e ious ield ips. Popula ions iden i ied h ough social media da a mining pos-
e io ly o he eDNA campaign we e no sampled o eDNA.
De elopmen o a eal- ime PCR assay speci ic o Pe ca lu ia ilis
New p ime s and p obe o he Eu opean pe ch we e designed due o he absence o
published p ime s a he ime ha could p o ide su icien speci ici y o ou a ge
species in he s udy a ea. The de ailed p ocedu e o designing and alida ing he new
p ime s and p obe is p o ided in Suppl. ma e ial 1. B ie ly, we compiled sequences o
wo mi ochond ial genes o he Pe cidae amily om Na ional Cen e o Bio ech-
nology In o ma ion (NCBI) nucleo ide da abase (h ps://www.ncbi.nlm.nih.go )
Figu e 1. S udy a ea maps o Eu opean pe ch dis ibu ion and de ec ions in Po ugal: A. Known Eu opean pe ch (Pe ca lu ia ilis) dis i-
bu ion in Po ugal and i s ela i e posi ion in Eu ope; B. Resul s o social media da a mining, whe e occu ences o Eu opean pe ch we e
iden i ied h ough online sou ces; C. En i onmen al DNA sampling g id and esul s, whe e in whi e a e nega i e esul s, yellow – incon-
clusi e de ec ions and in pu ple posi i e de ec ions; D. Con i med Eu opean pe ch popula ions h ough all me hods.
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Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
and aligned each da abase using MAFFT (Ka oh e al. 2019). P ime Ques ™ was
used o iden i y p ime and p obe candida e egions in he a ge species and hese
egions we e subsequen ly manually e ined based on he e e ence alignmen s isu-
alized in BioEdi (Hall 1999). Regions we e selec ed wi h he in en o maximizing
misma ches wi h non- a ge species, pa icula ly Sande luciope ca ( he only o he
pe cid in he s udy a ea), while ensu ing no misma ches wi h he a ge species.
Candida e se s we e assessed wi h OligoAnalyze ™ o he modynamic p ope ies
(Tm, GC con en , seconda y s uc u es). Speci ici y was e alua ed in silico using
eDNAssay (K onenbe ge e al. 2022) agains a comp ehensi e sequence da abase o
23 ish species om he s udy a ea (also e ie ed om NCBI’s da abase). eDNAssay
is a eely a ailable web-based ool (h ps://na ionalgenomicscen e .shinyapps.io/
eDNAssay) ha uses machine lea ning ( andom o es models) o p edic he likeli-
hood o ampli ica ion be ween a se o p ime s/p obe and a se o DNA sequences.
Among all se s es ed, he P luCy b p ime -p obe se showed he highes ampli ica-
ion p obabili y o P. lu ia ilis wi h a e y low likelihood o c oss-ampli ica ion in
non- a ge species. This se o p ime s (P luCy b-F: 5’-CCTCCATCCTGGTTCT-
TATAGTT-3’; and P luCy b-R: 5’-AGGATAACAACATCTGCGATTAATGT-3’)
and p obe (P luCy b-P: 5’-ATTGGGAGAGCGGTCGGAATGTAATGCCA-3’)
a ge s a 113 base pai egion o he Cy och ome b mi ochond ial gene. In i o
alida ion was pe o med on issue samples om he a ge species and ou sympa -
ic non- a ge species, including Sande luciope ca and o he locally abundan axa.
A his s age, no addi ional pe cid species we e es ed beyond hose p esen a ou
s udy si e, which should be conside ed when applying his assay in o he egions.
The qPCR assay was pe o med using he Quan S udio™ 5 Real-Time PCR Sys em
(The mo Scien i ic, Massachuse s, USA) unde he ollowing p o ocol: 10 s a 95
°C, ollowed by 40 cycles o 15 s a 95 °C and 60 s a 60 °C. Each PCR eac ion con-
ained a o al olume o 10 μl, consis ing o 5 μl TaqMan™ En i onmen al Mas e
Mix 2.0 (Applied Biosys ems, Cali o nia, USA), 0.4 μl each p ime (bo h a 10 μM;
S ab Vida, Capa ica, Po ugal), 0.13 μl o p obe (100 μM; Eu o ins, Luxembou g),
3.07 μl o s e ile ul apu e wa e , and 1.0 μl o DNA. Reac ions we e un in dupli-
ca e and nega i e con ols included. The P luCy b se showed clea ampli ica ion
only in he a ge species, con i ming i s speci ici y.
Assay pe o mance was e alua ed using a 5- old se ial dilu ion o a ge species’
DNA, ollowing he same p o ocol as abo e excep o he DNA olume (2.0 μl)
and wa e olume (2.07 μl) and all concen a ions we e un in iplica e. The s an-
da d cu e demons a ed high linea i y (R2 = 0.9973) and e iciency (101.3%),
wi h C a iabili y < 0.3 ac oss eplica es.
Labo a o y es s o en i onmen al samples
Labo a o y p ocessing o he eDNA samples, including DNA ex ac ion and PCR,
was conduc ed in dedica ed acili ies exclusi ely used o handling non-in asi e
samples, meaning ma e ial collec ed wi hou cap u ing, handling, o di ec ly in-
e ac ing wi h he a ge o ganism. DNA ex ac ions we e pe o med using he
DNeasy Blood and Tissue Ki (Qiagen, Inc., Hilden, Ge many), ollowing he
manu ac u e ’s guidelines wi h ew modi ica ions de ailed in Suppl. ma e ial 2.
In each ex ac ion ba ch, 6 andomly chosen samples we e p ocessed alongside an
ex ac ion blank ( om ini ial 50 ml o Longmi e bu e ). Ex ac ion success was
assessed by aga ose gel elec opho esis (0.8%).
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Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
All eDNA samples and blanks we e es ed in iplica e o he p esence o Eu o-
pean pe ch using he las p o ocol desc ibed abo e. Each qPCR un included pos-
i i e con ols (genomic DNA Eu opean pe ch a 78.97 ng/μl) and a nega i e con-
ol (s e ile ul apu e wa e ). A eplica e was conside ed posi i e i an exponen ial
ampli ica ion cu e was obse ed (cycle h eshold, CT < 34). In cases whe e some
ampli ica ion was obse ed bu he ampli ica ion cu e did no ollow a gene al
exponen ial pa e n), he eplica e was conside ed inconclusi e. Si es we e deemed
posi i e i a leas wo eplica es displayed CT alues below 34, and nega i e i none
o he eplica es showed posi i e ampli ica ion. In cases whe e only one eplica e
was posi i e, o i he e we e inconclusi e esul s ac oss eplica es (e.g., one posi-
i e, one inconclusi e, and one nega i e), we conside ed he p esence o Eu opean
pe ch in he sample as “Inconclusi e”.
Gi en ha eDNA de ec abili y can be a ec ed by se e al en i onmen al ac o s
which can lead o alse nega i es, we an wo addi ional qPCR assays, wi h adjus -
men s in sample inpu olume. In one essay, we hal ed he inpu olume o he
sample (1 μl) o educe he impac o po en ial inhibi o s, and, in he o he assay,
we used an inpu sample olume wo imes highe han in he o iginal assay (4 μl)
o accoun o e y low concen a ions o eDNA a he sampling si es (Noguei a e
al. 2025). These wo addi ional assays we e un o all he samples wi h nega i e o
inconclusi e esul s in he o iginal assays and ollowed he same p o ocol as abo e.
A ese oi / i e was classi ied as posi i e o inconclusi e i a leas one si e wi h-
in i yielded a posi i e o inconclusi e esul , ollowing a p ecau iona y p inciple.
Resul s
A o al o 153 social media pos s ela ed o Eu opean pe ch we e iden i ied be ween
May 2021 and Decembe 2024 (Fig. 2; See Suppl. ma e ial 3). O hese, 43 pos s
we e excluded om he species dis ibu ion analysis due o he absence o pho o-
g aphic e idence, lack o cap u e- ela ed con en , o e e ences o loca ions ou side
mainland Po ugal (e.g., he Azo es, F ance, and Spain). These excluded pos s yp-
ically included ishing- ela ed ques ions o gene al in o ma ion abou he species.
The emaining 110 pos s (100 om Facebook and 10 om YouTube) we e analyzed
o de e mine cap u e loca ions based on loca ion ags, pos desc ip ions, commen s,
and pho og aphic eco ds. In addi ion o known popula ions in PEPA and Sabugal,
wo new loca ions, Ba ocas and Meimoa (Figs 1B, 2), we e iden i ied in mul iple
pos s be ween 2021 and 2023. A new ese oi , Bouça Co a, was e e enced in pos s
beginning in July 2024 (Fig. 2). The numbe o social media pos s has inc eased ex-
ponen ially o e ime, wi h he a i al o he species in new loca ions igge ing a p o-
po ional ise in publica ions. Mo eo e , he in aded a ea also inc eased d ama ically
wi h he second loca ion, which is he la ges ese oi in su ace a ea and cu en ly
his in asi e ish has occupied a o al o 1000 ha in Po uguese wa e sheds (Fig. 3).
Fish sampling con i med he p esence o Eu opean pe ch in bo h Ba ocas and
Meimoa ese oi s. A o al o 57 indi iduals we e cap u ed in Ba ocas and 27 in
Meimoa, wi h sizes anging om 7.9 cm o 23.7 cm, p edominan ly comp ised
by ma u e indi iduals. Elec o ishing conduc ed ups eam and downs eam o he
ou known popula ion si es (a he ime) cap u ed en Eu opean pe ch ups eam
o Meimoa ese oi and one indi idual downs eam o he dam. No Eu opean
pe ch we e de ec ed in s eams ou side he ese oi s associa ed wi h he o he
h ee sampled popula ions (PEPA, Sabugal, and Ba ocas).
216
NeoBio a 102: 209–226 (2025), DOI: 10.3897/neobio a.102.151710
Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
Unde he o iginal qPCR condi ions, Eu opean pe ch was de ec ed in 11 o he 52
sampled si es (Fig. 1C, Table 1). In all si es wi h posi i e eDNA de ec ions, all h ee
qPCR eplica es we e posi i e. All eigh si es sampled wi hin he ou ese oi s con-
i med o hos Eu opean pe ch popula ions es ed posi i e: PEPA (one si e), Sabugal
( h ee si es), Meimoa ( h ee si es) and Ba ocas (one si e). The i e s downs eam o
hese ese oi s es ed posi i e in Meimoa and Sabugal, whe eas in PEPA and Ba o-
cas es ed nega i e. The emaining posi i e de ec ion ep esen ed a new loca ion o
his species in Penha Ga cia ese oi (Fig. 1C). This occu ed a one o he wo si es
sampled in he ese oi , wi h he o he si e a his ese oi yielding an inconclu-
si e esul (one posi i e ou o h ee eplica es). Two o he ese oi s, Ma a eca and
P acana, whe e i e si es we e sampled wi hin each ese oi , as well as he A e Ri e ,
whe e i e si es we e sampled along he i e , yielded one inconclusi e si e each o
he p esence o Eu opean pe ch (Fig. 1C). The addi ional es s a ying sample inpu
esul ed in inconclusi e de ec ions o one si e in Penha Ga cia unde dilu ed con-
cen a ion condi ions, and one in P acana unde inc eased concen a ion condi ions.
No Eu opean pe ch DNA was de ec ed in he emaining si es ac oss 11 ese oi s
(Fig. 1C). None o he nega i e con ols added showed signal o ampli ica ion.
Figu e 2. Cumula i e social media men ions o Eu opean pe ch: Cumula i e numbe o social me-
dia pos s de ec ed ega ding he Eu opean pe ch h ough ime, wi h he i s occu ence o each
popula ion ma ked in ed.
Figu e 3. Cumula i e in aded a ea by Eu opean pe ch in Po ugal: Cumula i e in aded a ea by Eu-
opean pe ch h ough ime, wi h social media assessed de ec ions in g een, eDNA posi i e de ec ions
in pu ple and eDNA inconclusi e de ec ions in Yellow.
217
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Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
Discussion
In his s udy, we show ha social media da a mining o in asi e ish can e ec i ely
guide a ge ed eDNA-based moni o ing, op imizing he sea ch a ound known o
suspec ed loca ions and, consequen ly, con i m ecen ly es ablished popula ions.
By analyzing nea by loca ions likely o be colonized, as well as po en ial ishing
ho spo s, we iden i ied a o al o ou un epo ed popula ions and h ee suspec ed
locali ies o Eu opean pe ch in mainland Po ugal (Fig. 1C, D, Table 1). P io o
his wo k, Eu opean pe ch was known o be p esen in only wo ese oi s (PEPA
and Sabugal, Fig. 1A), occupying an a ea o 714 ha which has cu en ly isen o
1026 ha. This app oach signi ican ly educed he species de ec ion ime lag, be-
ween i s a i al and con i ma ion in new a eas, enabling mo e imely and e ec i e
managemen esponses, such as local con ainmen o local e adica ion.
The ise o social media has acili a ed angle s’ sha ing o ishing expe iences
online, c ea ing a aluable and publicly accessible da a sou ce (Lennox e al. 2022).
By moni o ing Eu opean pe ch ela ed publica ions, we iden i ied p e iously un-
known popula ions in h ee ese oi s, Ba ocas, Meimoa and Bouça Co a (Fig. 1B,
Table1). The po en ial o his app oach o moni o ing his species was i s demon-
s a ed in i s i s eco d in mainland Po ugal (Banha e al. 2015), which elied
on da a om online ishing o ums. O he s udies u he demons a ed his wi h
Table 1. Summa y o main esul s by loca ion, including main loca ion coo dina es (p ima ily ese oi s; lo ic sys ems a e indica ed
wi h *) ha a e ep esen a i e o he sampled wa e body, and he numbe o il a ion si es pe loca ion (see Suppl. ma e ial 4 o de ails).
Eu opean pe ch de ec ion is epo ed by me hod: “X” indica es de ec ion (e en i inconclusi e), “0” indica es no de ec ion, and “N/A”
deno es ha he me hod was no applied a ha si e. The able also iden i ies he me hod by which he species was i s de ec ed a each
loca ion and e alua es he likelihood o an es ablished Eu opean pe ch popula ion based on he de ec ion e idence.
Main loca ions
( ese oi s/ i e s) Coo dina es Fil a ion si es Social media eDNA Scien i ic
ishing 1s Suspicion P esence
Penha-Ga cia 40°02'44.3"N, 7°00'54.5"W 2 0 X N/A eDNA Highly likely
Idanha-a-No a 39°56'41.1"N, 7°12'00.0"W 5 0 0 N/A – No e idence
Ma a eca 39°58'10.2"N, 7°28'57.0"W 5 0 X 0 eDNA Somewha likely
P acana 39°33'54.1"N, 7°48'43.5"W 5 0 X 0 eDNA Somewha likely
PEPA 39°43'21.0"N, 7°53'57.6"W 2 X X X Social Media Con i med
Pisco 40°01'24.8"N, 7°33'23.6"W 2 0 0 N/A – No e idence
P. Redondo 40°03'44.8"N, 7°32'24.8"W 1 0 0 N/A – No e idence
Capinha 40°12'53.3"N, 7°22'59.1"W 1 0 0 N/A – No e idence
Mon e Bispo 40°15'30.9"N, 7°19'23.2"W 1 0 0 N/A – No e idence
Esca igo 40°15'25.9"N, 7°17'10.1"W 1 0 0 N/A – No e idence
Meimoa 40°15'33.7"N, 7°08'23.7"W 3 X X X Social Media Con i med
Meimoa s eam* 40°15'33.7"N, 7°08'23.7"W 1 0 X X Scien i ic Fishing Con i med
Ba ocas 40°28'49.9"N, 6°51'18.6"W 2 X X X Social Media Con i med
Sabugal 40°19'53.2"N, 7°05'42.5"W 3 X X X Social Media Con i med
Côa Ri e * 40°19'53.2"N, 7°05'42.5"W 1 0 X N/A eDNA Highly likely
Vasco ei o 40°42'42.2"N, 7°05'39.0"W 2 0 0 N/A – No e idence
S a do Mon o e 40°47'12.7"N, 7°00'43.1"W 1 0 0 N/A – No e idence
Ve miosa 40°48'17.7"N, 6°53'20.0"W 2 0 0 N/A – No e idence
S a Ma ia do Aguia 40°51'52.7"N, 6°53'09.4"W 2 0 0 N/A – No e idence
E mal 41°35'05.4"N, 8°08'10.1"W 2 0 0 N/A – No e idence
A e Ri e * 41°21'17.2"N, 8°27'21.7"W 5 0 X N/A eDNA Highly likely
Bouça Co a 40°41'59.3"N, 7°14'48.2"W 0 X N/A N/A Social Media Highly likely
224
NeoBio a 102: 209–226 (2025), DOI: 10.3897/neobio a.102.151710
Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
Loeza-Quin ana T, Abbo CL, Hea h DD, Be na chez L, Hanne RH (2020) Pa hway o Inc ease S an-
da ds and Compe ency o eDNA Su eys (PISCeS)—Ad ancing collabo a ion and s anda diza ion
e o s in he ield o eDNA. En i onmen al DNA 2: 255–260. h ps://doi.o g/10.1002/edn3.112
Longmi e JL, Mal bie M, Bake RJ (1997) Use o “lysis bu e ” in DNA isola ion and i s implica ion
o museum collec ions. h ps://doi.o g/10.5962/bhl. i le.143318
Ma elo J, Cos a LM, Ribei o D, Gago J, Magalhães MF, Gan e HF, Al es MJ, Cheoo G, Gkenas
C, Banha F (2021) E alua ing he ange expansion o ec ea ional non-na i e ishes in Po u-
guese eshwa e s using scien i ic and ci izen science da a. BioIn asions Reco ds 10: 378–389.
h ps://doi.o g/10.3391/bi .2021.10.2.16
Ma inez B, Rease JK, Dehgan A, Zam B, Baisch D, McCo mick C, Gio dano AJ, Aiche R, Selbe
S (2020) Technology inno a ion: Ad ancing capaci ies o he ea ly de ec ion o and apid esponse
o in asi e species. Biological In asions 22: 75–100. h ps://doi.o g/10.1007/s10530-019-02146-y
McDonald LL, Thompson WL (2004) Sampling a e popula ions. Sampling a e o elusi e species:
concep s, designs, and echniques o es ima ing popula ion pa ame e s, 11–42.
Monkman GG, Kaise M, Hyde K (2018) The E hics o Using Social Media in Fishe ies Resea ch.
Re iews in Fishe ies Science & Aquacul u e 26: 235–242. h ps://doi.o g/10.1080/23308249.2
017.1389854
Mo gan DL, Hamble on SJ, Gill HS, Bea y SJ (2002) Dis ibu ion, biology and likely impac s o
he in oduced ed in pe ch (Pe ca lu ia ilis) (Pe cidae) in Wes e n Aus alia. Ma ine and F esh-
wa e Resea ch 53: 1211–1221. h ps://doi.o g/10.1071/m 02047
Mo gan DL, Gill HS, Madde n MG, Bea y SJ (2004) Dis ibu ion and impac s o in oduced
eshwa e ishes in Wes e n Aus alia. New Zealand Jou nal o Ma ine and F eshwa e Resea ch
38: 511–523. h ps://doi.o g/10.1080/00288330.2004.9517257
Ning N, Ba low C, Baumga ne LJ, B e zel JB, Doyle KE, Du y D, P ice A, Vu AV (2025) A global
e iew o he biology and ecology o he Eu opean pe ch, Pe ca lu ia ilis. Re iews in Fish Biology
and Fishe ies 35: 587–618. h ps://doi.o g/10.1007/s11160-025-09924-z
Noguei a S, Cu o M, Dias D, Al es MJ, Ama al SD, Magalhães MF, Ca apa o C, Ve íssimo A,
Ribei o F (2025) En i onmen al DNA Templa e Va ia ion: I s Rele ance o Species De ec ion
and Conse a ion. F eshwa e Biology 70: e70019. h ps://doi.o g/10.1111/ wb.70019
Pa ondo M, Clusa L, Mau isseau Q, Bo ell YJ (2018) Ci izen wa nings and pos checkou molecu-
la con i ma ions using eDNA as a combined s a egy o upda ing in asi e species dis ibu ions.
Jou nal o Na u e Conse a ion 43: 95–103. h ps://doi.o g/10.1016/j.jnc.2018.02.006
Pawlowski J, Apo héloz-Pe e -Gen il L, Al e ma F (2020) En i onmen al DNA: Wha ’s behind
he e m? Cla i ying he e minology and ecommenda ions o i s u u e use in biomoni o ing.
Molecula Ecology 29: 4258–4264. h ps://doi.o g/10.1111/mec.15643
Pon D, Rocle M, Valen ini A, Ci ade R, Jean P, Mai e A, Rose N, Schabuss M, Zo nig H, Dejean
T (2018) En i onmen al DNA e eals quan i a i e pa e ns o ish biodi e si y in la ge i e s
despi e i s downs eam anspo a ion. Scien i ic Repo s 8: 10361. h ps://doi.o g/10.1038/
s41598-018-28424-8
Ribei o F, Ve íssimo A (2014) Full wes wa d expansion o Ru ilus u ilus (Linnaeus, 1758) in he Ibe-
ian Peninsula. Jou nal o Applied Ich hyology 30: 540–542. h ps://doi.o g/10.1111/jai.12418
Ribei o F, Colla es-Pe ei a MJ, Moyle PB (2009) Non-na i e ish in he esh wa e s o Po ugal,
Azo es and Madei a Islands: A g owing h ea o aqua ic biodi e si y. Fishe ies Managemen and
Ecology 16: 255–264. h ps://doi.o g/10.1111/j.1365-2400.2009.00659.x
Ribei o D, Gkenas C, Gago J, Ribei o F (2021) Va ia ion in Die Pa e ns o he In asi e Top
P eda o Sande luciope ca (Linnaeus, 1758) ac oss Po uguese Basins. Wa e (Basel) 13: 2053.
h ps://doi.o g/10.3390/w13152053
225
NeoBio a 102: 209–226 (2025), DOI: 10.3897/neobio a.102.151710
Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
Sb agaglia V, Espasandín L, Coco S, Felici A, Co eia RA, Coll M, A linghaus R (2022) Rec ea ional
angling and spea ishing on social media: Insigh s on ha es ing pa e ns, social engagemen and
sen imen s ela ed o he dis ibu ional ange shi o a ma ine in asi e species. Re iews in Fish
Biology and Fishe ies 32: 687–700. h ps://doi.o g/10.1007/s11160-022-09699-7
S epien CA, Beh mann-Godel J, Be na chez L (2015) E olu iona y ela ionships, popula ion gene -
ics, and ecological and genomic adap a ions o pe ch (Pe ca). Biology o pe ch, 7–46. h ps://doi.
o g/10.1201/b18806-3
S aye DL, D’An onio CM, Essl F, Fowle MS, Geis J, Hil S, Ja ić I, Jöhnk K, Jones CG, Lambin
X, La zka AW, Pe gl J, Pyšek P, Robe son P, on Schmalensee M, S e ansson RA, W igh J,
Jeschke JM (2017) Boom-bus dynamics in biological in asions: Towa ds an imp o ed applica-
ion o he concep . Ecology Le e s 20: 1337–1350. h ps://doi.o g/10.1111/ele.12822
Tabe le P, Coissac E, Pompanon F, B ochmann C, Wille sle E (2012) Towa ds nex -gene a-
ion biodi e si y assessmen using DNA me aba coding. Molecula Ecology 21: 2045–2050.
h ps://doi.o g/10.1111/j.1365-294X.2012.05470.x
Vande Zanden MJ, Hansen GJA, Higgins SN, Ko nis MS (2010) A pound o p e en ion, plus a
pound o cu e: Ea ly de ec ion and e adica ion o in asi e species in he Lau en ian G ea Lakes.
Jou nal o G ea Lakes Resea ch 36: 199–205. h ps://doi.o g/10.1016/j.jgl .2009.11.002
Ven u elli PA, Hyde K, Sko C (2017) Angle apps as a sou ce o ec ea ional ishe ies da a:
Oppo uni ies, challenges and p oposed s anda ds. Fish and Fishe ies 18: 578–595. h ps://doi.
o g/10.1111/ a .12189
Vi ale G, Dedeu AL, Pujol M, Sb agaglia V (2021) Cha ac e izing he P o ile o Rec ea ional Fishe s
Who Sha e Thei Ca ches on Social Media. F on ie s in Ma ine Science 8: 768047. h ps://doi.
o g/10.3389/ ma s.2021.768047
Zamo a-Ma ín J, Ruiz-Na a o A, O icialdegui F, Anas ácio P, Mi anda R, Ga cía-Mu illo P, Cobo
F, Ribei o F, Galla do B, Ga cía-Be hou E, Boix D, Medina Domingo L, Mo cillo Alonso F,
Oscoz J, Guillén A, He e o-Reyes A, Aguia F, Almeida D, A ias A, Ay es C, Banha F, Ba ca S,
Biu un I, Cabezas P, Cale o S, Campos J, Capde ila-A güelles L, Capinha C, Ca ape o A, Casals
F, Chainho P, Ci ujano S, Cla e o M, Cues a J, Del o o V, Enca nação J, Fe nández-Delgado C,
F anco J, Ga cía-Mesegue A, Gua eschi S, Gue e o-Gómez A, He moso V, López-Cañiza es
C, López-So iano J, Macho dom A, Ma elo J, Mellado-Díaz A, Mo eno J, Oli o del Amo R,
O e o C, Pe dices A, Pou-Ro i a Q, Quiñone o-Salgado S, Rod íguez-Me ino A, Ros M, Sán-
chez-Gullón E, Sánchez M, Sánchez-Fe nández D, Sánchez-González J, So iano O, Teodósio A,
To al a M, Viei a-Lane o R, Zamo a-López A, Oli a-Pa e na F (2023) A mul i- axa assessmen
o aqua ic non-indigenous species in oduced in o Ibe ian eshwa e and ansi ional wa e s.
h ps://hdl.handle.ne /20.500.14352/96189 [July 12, 2025]
Supplemen a y ma e ial 1
DNA ex ac ion o en i onmen al samples collec ion
Au ho s: So ia Ba is a, So ia Noguei a
Da a ype: docx
Copy igh no ice: This da ase is made a ailable unde he Open Da abase License (h p://openda a-
commons.o g/licenses/odbl/1.0/). The Open Da abase License (ODbL) is a license ag eemen
in ended o allow use s o eely sha e, modi y, and use his Da ase while main aining his same
eedom o o he s, p o ided ha he o iginal sou ce and au ho (s) a e c edi ed.
Link: h ps://doi.o g/10.3897/neobio a.102.151710.suppl1
226
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Diogo Dias e al.: Combining social media and eDNA o enhance in asi e species ea ly de ec ion
Supplemen a y ma e ial 2
De elopmen o a eal- ime PCR assay speci ic o Pe ca lu ia ilis
Au ho s: So ia Ba is a, So ia Noguei a
Da a ype: docx
Copy igh no ice: This da ase is made a ailable unde he Open Da abase License (h p://openda a-
commons.o g/licenses/odbl/1.0/). The Open Da abase License (ODbL) is a license ag eemen
in ended o allow use s o eely sha e, modi y, and use his Da ase while main aining his same
eedom o o he s, p o ided ha he o iginal sou ce and au ho (s) a e c edi ed.
Link: h ps://doi.o g/10.3897/neobio a.102.151710.suppl2
Supplemen a y ma e ial 3
Da a mined in o ma ion om social media
Au ho s: Diogo Dias
Da a ype: xlsx
Copy igh no ice: This da ase is made a ailable unde he Open Da abase License (h p://openda a-
commons.o g/licenses/odbl/1.0/). The Open Da abase License (ODbL) is a license ag eemen
in ended o allow use s o eely sha e, modi y, and use his Da ase while main aining his same
eedom o o he s, p o ided ha he o iginal sou ce and au ho (s) a e c edi ed.
Link: h ps://doi.o g/10.3897/neobio a.102.151710.suppl3
Supplemen a y ma e ial 4
Summa y able o esul s
Au ho s: Diogo Dias
Da a ype: docx
Copy igh no ice: This da ase is made a ailable unde he Open Da abase License (h p://openda a-
commons.o g/licenses/odbl/1.0/). The Open Da abase License (ODbL) is a license ag eemen
in ended o allow use s o eely sha e, modi y, and use his Da ase while main aining his same
eedom o o he s, p o ided ha he o iginal sou ce and au ho (s) a e c edi ed.
Link: h ps://doi.o g/10.3897/neobio a.102.151710.suppl4
