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The current ecology of Solway shad
and ongoing efforts to locate
potential spawning areas
Liz Etheridge

River Cree rare fish project
• Action on eight species
The Tubney Environmental Trust,
The Esmée Fairbairn Foundation,
GFT, SEPA, SNH, FCS, Scottish
Government, SWEAT and Crown
Estates.
• Anadromous fishes
– Freshwater pearl mussels
– Sparling
– Sea, river and brook lamprey
– Atlantic salmon
– Allis and twaite shad
– Vulnerable to human impacts
• Pollution
• Barriers to migration
• Migrations vulnerable to
overfishing
• May require several different
habitats to complete lifecycle

Allis and Twaite shad
• Two species of shad in UK
– Overlap in many life history and
taxonomic characters
– Identified through counting gill
rakers
• Both found around the UK coast
– Numbers of both species have
declined
– However, allis shad is rarer than
twaite shad
• Both species are protected in the
UK
• Spawning sites are known in
Wales and England
• Shad in scotland
Firths of
Tay and
Forth
Solway Firth
– Have been reported for several
years in the Solway Firth
– Have also been reported in some
east coast rivers
• E.g. Tay, Forth and Tweed

Shad in the Solway
• Have been regularly captured in the
Solway Firth for many years
– By-catch from salmon stake nets
• Adult fish first collected and studied
between 1989 and 1994
– Peter Maitland during work on River
Cree smelt
• Capture of both species and a small
number of hybrids
– suggested that spawning might be
taking place in the Cree or Bladnoch
• From 2004 shad samples were
again collected from stake nets
in the Solway
– Part of monitoring work for an
offshore windfarm
– Reward paid for each fish to
enable maximum data
collection

Spawning ground location
• Important
– Climate change is expanding the northerly range of many species
– More northerly spawning areas need to be located in order to ensure protection
• May become more important
– Possible developments in the area
• Solway Barrage has been suggested
• More offshore wind farms
• Not thought that these fish can be
ascending far up the river
– Both the Bladnoch and the Cree are
fished recreationally for salmon
– Both have weirs which might hold up
migrating shad
– Spawning shad relatively obvious?
But no obvious spawning grounds!

Solway shad 2010
• 86 shad were captured in 2010
• From six netting stations
– Cree, Fleet, Urr, Annan

Solway shad ecology 2010
• Species identification
• Gill raker number (GR)
– 8 allis shad (104 - 127)
– 74 twaite shad (36 - 47)
– 4 hybrid shad (74 - 80)

• No significant difference in L f
or W
between groups
• Allis shad has a faster growth rate
than twaite shad
• Sex ratio
– Allis shad and hybrid catches
dominated by males
– Captured twaite shad were mostly
female

Solway shad spawning 2010
30
hybrid
N shad caught
25
20
15
10
5
0
Twaite
Allis
Apr May Jun Jul Aug
• Gonadosomatic index (GSI)
– GSI = (W gonad x 100) / W total
– GSI reduces over time
• fish ripe to spent
– Appear to suggest fish start spawning in
June

• Ripe fish still present in July
– By end of July all fish are spent

2010 spawning
N shad caught
50
45
40
35
30
25
20
15
10
5
0
Cree
hybrid
Twaite
Allis
Urr
Fleet
Annan
KB KD SC CN
KB (N = 44)
DH AY
DH (N = 19)
Site
• Most shad captured – Kirkbride (KB) nets (Cree)
– Douglas Hall (DH) nets (Urr)

Shad 1989 - 2010
• 512 shad were captured in Solway
• From seven netting areas

Solway shad 1989 - 2010
120
100
Frequency
80
60
40
20
0
40 50 60 70 80 90 100 110 120 130
Gill raker number
• No significant difference in L f
or W between groups
• Sex ratio
– All groups dominated by
females
100%
• Species identification
• Gill raker number (GR)
– Allis shad > 90 GR
– Twaite shad < 60 GR
– Hybrid shad 60 to 90 GR
80%
60%
40%
20%
0%
Allis
Twaite hybrid
female
male

Solway shad spawning
N shad caught
180
160
140
120
100
80
60
40
20
hybrid
Twaite
Allis
mean GSI
14
12
10
8
6
4
Shad spawning
in freshwater?
0
2
Apr May Jun Jul Aug Sept
0
Apr May Jun 1 Jul
Aug
Sep
• Gonadosomatic index (GSI)
– GSI reduces over time, fish ripe to spent
– Appear to suggest main spawning occurs in
July

35
allis
Gonadosomic index
30
25
20
15
10
5
Shad spawning
in freshwater?
hybrid
twaite
0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190
Days since 1st April
• Gap apparent in July where shad are usually not captured
• After this almost all are spent

Solway Shad spawning
• Over the whole sampling period, two likely spawning
areas are apparent
–

160
140
120
Cree
Urr
hybrid
Twaite
Allis
N shad caught
100
80
60
40
20
Luce
Fleet
Annan
0
SH IW CT CS FL PL BH
Site

Solway shad spawning
• Fish capture in July, when spawning is believed to be taking place
– Urr / Nith
– Cree / Bladnoch
• Shad captured in Wigtown Bay are
most often sampled from the
Carsluith nets (CS)
– Opposite the entrance to the
Bladnoch
• Fish running up the Cree would be
expected to be captured more
frequently in the Creetown nets (CT)
CT
CS
• Are shad more likely to be spawning
in the Bladnoch?

Conclusions
• Spawning sites and timing
– The data collected in 2010 and drawn from
previous studies from 1989 suggest
– Considering capture patterns, spawning is
likely to occur in mid July
– There may be two main areas of shad
spawning in the Solway
• Urr
• Bladnoch
• Future work
• Spawning locations now need to
be narrowed down
– Surveys of areas being planned
– Possibility of using sonar?
– Remote sensing?
• Juvenile surveys
– netting
• One of the Urr nets has been
releasing shad alive
– Possibility of tagging individuals?
– Don’t know condition

Thank you
for your attention.
Are there any questions?
www.gallowayfisheriestrust.org