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.