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What Makes migrationTough for Fish?
Identify the obstacles and check your answers on the right!
1.
Graz
ing
cattl
e ca
n da
mag
e riv
er b
anks
and
deg
rade
wat
er q
ualit
y.2.
Ru
noff
from
ferti
lizer
s ca
n de
grad
e w
ater
qua
lity.
3.
Irrig
atio
n ca
n re
duce
wat
er le
vels
; rem
aini
ng w
ater
can
then
bec
ome
too
war
m fo
r nat
ive
fishe
s.
4.
Hist
oric
mill
dam
s ca
n af
fect
the
natu
ral fl
ow o
f riv
ers
and
prev
ent fi
sh fr
om m
igra
ting.
5.
Trad
ition
al ro
und
culv
erts
tend
to h
inde
r or t
otal
ly b
lock
fish
mov
emen
t. 6.
N
on-n
ativ
e fis
h pr
ey o
n ju
veni
le m
igra
tory
fish
and
dis
rupt
the
food
cha
in.
7.
Dam
s m
ay d
elay
or t
otal
ly p
reve
nt m
igra
tion
and
alte
red
flow
may
favo
r non
-mig
rato
ry a
nd/o
r non
-nat
ive
fish.
8.
Pred
ator
s in
terc
ept m
igra
ting
fish
in c
oast
al w
ater
s.
9.
Was
te w
ater
dis
char
ge m
ay d
egra
de w
ater
qua
lity.
10.
See
5.11
. Fi
sh tr
appe
d be
low
cul
verts
can
be
easy
pre
y fo
r bird
s.12
. Se
e 5.
13.
See
4. A
band
oned
dam
s ar
e al
so u
nsaf
e.
14.
Year
s ag
o, ri
vers
wer
e st
raig
hten
ed s
o lo
gs c
ould
get
to m
ills.
Thi
s de
grad
ed fi
sh h
abita
t.
15.
Mig
rato
ry fi
sh m
ay b
e le
gally
har
vest
ed in
oth
er c
ount
ries;
her
e th
ey a
re s
old
in a
fish
mar
ket.
16.
Man
y sp
ecie
s of
bird
s ea
t mig
rato
ry fi
sh.
17.
Som
e m
igra
tory
fish
are
inte
rcep
ted
at s
ea e
n ro
ute
to a
nd fr
om s
paw
ning
hab
itat.
18.
Mig
rato
ry fi
sh a
re a
n im
porta
nt fo
od s
ourc
e fo
r bird
s lik
e ba
ld e
agle
s.19
. Ai
r pol
lutio
n fro
m fa
ctor
ies
and
sew
age
treat
men
t pla
nts
can
degr
ade
wat
er q
ualit
y.20
. M
igra
tory
fish
may
be
an u
nint
ende
d by
catc
h in
fish
erie
s ta
rget
ing
othe
r spe
cies
. 21
. M
igra
tory
fish
are
an
impo
rtant
nat
ural
food
sou
rce
for b
irds
like
ospr
eys.
22.
War
min
g of
rive
rs a
nd o
cean
s ca
n im
pact
fish
sur
viva
l. 23
. A
wes
t coa
st e
leph
ant s
eal m
ay p
rey
on m
igra
tory
fish
.24
. An
eas
t coa
st h
arbo
r sea
l may
pre
y on
mig
rato
ry fi
sh.
25.
The
brow
n pe
lican
is a
nat
ural
pre
dato
r of m
igra
tory
fish
. 26
. In
take
pip
es c
an s
uck
juve
nile
fish
into
the
indu
stria
l pla
nt’s
cool
ing
proc
ess.
27.
Aban
done
d da
ms
used
dur
ing
the
log
driv
e da
ys c
ontin
ue to
blo
ck fi
sh m
igra
tion.
28
. Se
e 5.
Und
ersi
zed
culv
erts
als
o di
srup
t nat
ural
flow
and
sed
imen
t tra
nsfe
r.
29.
A ch
angi
ng c
limat
e ca
n al
ter o
cean
ic c
urre
nts
vita
l to
mig
rato
ry fi
sh.