CA

LIF

OR

NIA

FIS

H A

ND

GA

ME

C

allto

rnia

Fish

and

Gam

e 90

(3):1

40-1

54

2004

CU

RR

EN

T S

TA

TU

S O

F S

OU

THE

RN

ST

EE

LHE

AD

1 R

AIN

BO

W T

RO

UT

IN S

AN

MA

TE

0 C

RE

EK

, CA

LIF

OR

NIA

TIM

E. H

OV

EY

C

alifo

rnia

Dep

artm

ent o

f F

ish

and

Gam

e 49

49 V

iew

ridge

Ave

nue

San

Die

go, C

A 9

2123

The

dis

cove

ry o

f a s

mall

popula

tion (

e70 in

div

idu

als

) of

south

ern

st

eelh

ead tr

out, O

nco

rhyn

chus

myk

iss

in S

an M

ate

o C

reek

(S

MC

) and

De

vil C

anyo

nC

reek (

DC

C),

asm

allt

rib

uta

ryto

SM

C, i

n San

Die

goC

ounty

, C

alif

orn

ia in

the s

pri

ng

199

9 re

pre

sents

the fi

rst m

ultip

le re

cord

acc

ount

oft

rou

t in

the

cre

eki

n o

ver5

0 y

ears

. Fro

m A

ugust

1999 to

Dec

embe

rZO

O3,

th

e C

alif

orn

ia D

epart

ment o

f F

ish

and G

ame

(Depart

ment)

conduct

ed a

to

talo

f45

surv

eys

alo

ng

both

creeks

tom

on

itort

he

sta

tuso

fth

etr

ou

t. D

ata

on

tro

ut a

bundance

,age a

nal

ysis

,wat

erte

mp

erat

ure

,sp

awn

ing

beh

avio

r a

nd

ge

ne

tica

na

lysi

swe

reco

llect

ed

du

rin

g th

esu

~ey

s.W

eob

serv

edth

at

tro

utn

urn

be

rso

nS

MC

began to

de

clin

esh

ort

ly a

fte

rth

esu

rve

ys b

eg

an

in

1999

, and th

at t

he la

st tr

ou

twa

s obse

rved in

Au

gu

st 2

000.

Juve

nile

tro

ut

were

dis

cove

red o

n D

CC

in

May

and J

uly

200

0 a

nd

matu

ring fis

h w

ere

con

tinu

ally

monito

red o

n D

CC

thro

ugh 2

001

an

d 2

002,

with

no

new

re

cruitm

ent r

eco

rded d

uri

ng

that t

ime.

Asi

ng

lea

du

lt h

old

ove

rtro

ut(

DC

2)

was

obse

rved o

n th

e c

onflu

ence

as

rece

ntly

as

Dece

mber o

f 200

3. W

ater

te

mpera

ture

data

co

llect

ed

on

bo

th c

reeks

suggest

ed

that

annual

tem

pera

ture

pro

file

sare

more

sla

ble

an

d s

uita

ble

fGso

uth

ern

steelh

ead

surv

ival i

n D

CC

than in

SM

C.W

eass

um

eth

atth

isd

iffe

ren

ceen

han

cest

rou

t su

rviv

al

in D

CC

. S

paw

nin

g b

ehavi

or

was

de

scri

be

d o

n t

wo d

iffere

nt

occ

asi

ons

on

DC

C,

ind

ica

ting

the p

ote

ntia

l fo

r re

sid

en

t re

pro

duct

ion.

How

eve

r, n

oa

ctu

als

pa

wn

ing

was

eve

r re

cord

ed

on

SM

Co

r DC

C. G

enetic

and a

ge a

naly

sis

on

speci

mens

colle

cted in

199

9 a

nd

200

0 est

ablis

hed

that a

t least

two p

airs

of anadro

mous

steelh

ead e

nte

red th

e d

rain

age in

19

97 to

spaw

n a

nd

that s

ucc

ess

ful,

resi

dent r

ep

rod

uct

ion

(FI)

occ

urr

ed

in D

CC

in

200

0.

Oto

lith

age

analy

sis

of

a s

ingle

ad

ult in

div

idu

al (

DC

l)

colle

cte

din

DC

Cin

2002 co

nfirm

ed

that m

atu

rin

g,s

ew

nd

genera

tion tr

out

(FZ

) occ

upie

d t

ha

t tr

ibuta

ry,

alb

eit

in e

xtre

mely

sm

all

num

bem

(C

8

indiv

iduals

). T

hen

um

ber

son

DC

Cco

nti

nu

edto

dro

pu

nti

lon

lyas

ing

lead

ult

tr

ou

t (33

7 m

m T

L) w

as

obse

rved d

uri

ng

a s

urv

ey

in D

ece

mber 2

003.

The

hig

her w

ate

r tem

pera

ture

and p

rese

nce

of n

on-n

atlv

e fl

sh s

peci

es

likely

co

ntr

ibu

ted

toth

eext

irp

atio

no

f ad

ultt

rou

t on S

MC

in

2000

. Conve

rsely

, the

lack

of

non-n

ativ

e fi

sh a

nd th

e m

ore

sta

ble

wate

r te

mpera

ture

in

DC

C

enable

d tr

ou

t to

su

rviv

e o

n th

e t

rib

uta

ry u

ntil t

he l

ow

wate

r co

nd

itio

ns

impact

ed th

eir n

um

bers

consi

dera

bly

.

INTR

OD

UC

TIO

N

Sou

ther

n st

eelh

ead

trou

t his

torica

lly o

ccur

red

from

San

to D

om

ingo R

iver

in

nort

hern

Baj

a C

alif

om

iato

Malib

u C

reek

, Calif

orn

ia. H

isto

ricre

cord

sals

o sh

ow th

at in

140

the

earl

y 19

00's

, San

Mat

eo C

reek

may

hav

e be

enon

e of

the

mos

t im

port

ant s

outh

ern

stee

lhea

d sp

awni

ng st

ream

son

the

sout

h co

ast (

USF

WS

Rep

ort 1

998'

). A

t the

irpe

ak,

the

San

Mat

eo C

reek

ste

elhe

ad r

uns

wer

e re

cord

ed a

s la

rge

and

cons

iste

nt, w

ith t

he

fish

doc

umen

ted

toat

tain

a la

rger

size

than

thei

rrel

ativ

es to

then

orth

. Des

pite

the

high

nu

mbe

rs r

ecor

ded

in th

e ea

rly

part

of

the

Cen

tury

, tro

ut s

ight

ings

dro

pped

off

in th

e 19

40's

and

the

1950

's a

nd c

onsi

sten

t tro

ut a

bund

ance

has

not

bee

n pr

esen

t with

in S

an

Mat

eoC

reek

orso

utho

fMal

ibuC

reek

in t

hela

st 5

0 ye

ars (

US

FW

S R

epor

t 1 99

S2). T

he

last

reco

rded

sig

htin

g of

mul

tiple

age

-cla

sses

of

sout

hern

ste

elhe

ad o

n SM

C w

as in

19

50 du

ring

a D

ep

ah

en

t str

eam

sur

vey.

Sin

ce th

en, o

nly

anec

dota

l obs

erva

tions

of

trou

t on

the

cree

k ha

ve b

een

reco

rded

. Si

nce t

hat t

ime,

inco

nsis

tent

wat

er a

vaila

bilit

y du

e to

an

incr

ease

in g

roun

d w

ater

pu

mpi

ng b

egin

ning

in th

e la

te 1

950'

s an

d th

e ne

gativ

e in

flue

nce o

f non

nativ

e pl

ants

, (T

amar

isk

sp.),

beg

an t

o co

ntri

bute

to t

he a

ltera

tion

of s

trea

m h

abita

t with

in S

MC

. C

ritic

al s

trea

m s

truc

ture

s fo

r tro

ut re

prod

uctio

n, s

uch

as ri

ffle

s an

d gr

avel

bed

s no

w

sitd

ry an

duse

less

due

toal

tere

d fl

ow d

ynam

ics.

Inco

nsis

tent

wat

erle

vels

also

redu

ces

thea

mou

nt o

ftim

e SM

C re

mai

ns o

pen

to th

e oc

ean,

furt

herl

imit

ingu

pstr

cam

mig

mti

on

of s

outh

ern

stee

lhea

d, a

s w

ell a

s do

wns

trea

m e

mig

ratio

n of

resi

dent

fis

h.

Furt

her

effe

ctin

g tr

out p

rese

nce

was

the

intr

oduc

tion

of n

onna

tive

terr

estr

ial a

nd

aqua

tic s

peci

es (

larg

emou

th b

ass,

Mic

ropt

erns

sal

moi

des,

grc

cn s

unfi

sh, L

epom

is

cyan

ellu

s, b

lueg

ill, L

epom

is m

acro

chir

us, b

lack

bul

lhea

d, A

mei

unrs

mel

as, m

osqu

ito

fish

, G

ambu

sia

afln

is,

swam

p cr

ayfi

sh,

Pro

cam

baru

s cl

arki

i, an

d bu

llfro

g, R

ana

cate

sbei

ana)

into

San

Mat

eo C

reek

. The

sc sp

ccie

s hav

e be

en d

ocum

ente

d to

incr

ease

co

mpe

titiv

e an

dpre

dato

ry im

pact

s on

seas

onal

salm

onid

runs

, as w

ell a

s res

iden

t tro

ut

popu

latio

ns. S

teel

head

that

wer

e fo

rtun

ate

enou

gh to

find

per

iodi

c av

aila

ble

wat

er to

m

igra

te u

pstr

eam

, oft

en f

ound

thei

r sp

awni

ng g

roun

ds in

fcst

ed w

ith n

onna

tive

fish

sp

ecie

s, h

eavi

ly i

mpa

ctin

g re

prod

uctiv

e su

cces

s.

Due

to th

ese

two

fact

ors (

alte

red

habi

tat a

nd th

e int

rodu

ctio

n of

aqua

tic,

non

nativ

e sp

ecie

s), i

t was

gen

eral

ly c

oncl

uded

that

sou

lhem

stee

lhea

d tr

out w

ere

extin

ct s

outh

of

Mal

ibuC

reek

, Cal

ifom

ia.

The

dec

line

in q

ualit

y, s

outh

ern

stee

lhea

d ha

bita

t an

d th

e ab

senc

e of

ste

elhe

ad

trou

t insouthemCalifornia,pro~nptedtheNational Mar

ineF

ishe

ries

Ser

vice

(NM

FS)

to li

st s

outh

ern

Cal

ifor

nia'

s E

volu

tiona

rily

Sig

nifi

cant

Uni

t (E

SU)

for

anad

rom

ous

stee

lhea

d as

an en

dang

ered

spec

ies i

n 19

97 (F

eder

al R

egis

try

62 F

R43

937)

. Thi

s lis

ting,

ho

wev

er, d

esig

nate

d th

e cu

rren

t sou

them

ES

U b

ound

ary

as M

alib

u C

reek

, Cal

ifor

nia

and

prot

ectio

n w

as e

xclu

ded

for a

ll po

tent

ial

wat

erw

ays

sout

h of

that

bo

un

d~

. T

he d

isco

very

of

sout

hern

ste

elhe

adlr

ainb

ow t

rout

, O

ncor

hync

hus

myk

iss,

on

SM

C an

dDev

il C

anyo

n C

reek

(DC

C) a

smal

l tri

buta

ly to

SM

C, i

nSan

Die

go C

ount

y,

'U.S

. Fi

sh a

nd W

ildlif

e Se

rvic

e. 1

998,

Sou

ther

n St

eelh

ead

Onc

orhy

nchu

s m

ykiss

Hab

itat

Suita

bilit

ysur

veyo

Clh

e San

laM

arga

ritaR

iver

, San

Mat

eo an

dSan

Ono

6eC

reek

sonM

arin

e C

orps

Bas

e, C

amp

Pend

leto

n. C

oast

al C

alifo

mia

Fish

and

Wild

life O

ffic

e, A

rcat

a, C

A.

Prep

ared

for A

ssis

tant

Chi

ef o

f Sta

ff, E

nviro

nmen

tal S

ecur

ity.

'U.S

. Fish

and

Wild

life

Serv

ice.

199

5, S

anta

Mar

gari

tn R

iver

and

San

Mat

eu C

reek

Sal

mon

id

Stud

y. P

rogr

ess

Rep

ort

prep

ared

for

Cam

p Pe

ndle

ton

Mar

ine

Cor

ps. B

ase,

Jan

uary

- Se

ptem

ber 1

995.

Coa

stal

Cal

iforn

ia F

ish a

nd W

ildlif

e Off

ice.

Arc

ata,

CA

.

142

CA

LIF

OR

NIA

FIS

H A

ND

GA

ME

Cal

ifor

nia d

urin

g sp

ring

199

9, es

tabl

ishe

d a

need

to e

xten

d th

e ne

wly

des

igna

tedE

SU

bo

unda

ry. T

he p

opul

atio

n si

ze, t

houg

h ne

ver

accu

rate

ly d

eter

min

ed, w

as e

xtre

mel

y sm

all (<70individuals).whichlimitedthenumberofsamplesthatcouldbecollected(l0

adul

ts in

199

9 an

d 5

juve

nile

s in

200

0) f

or a

naly

sis.

Des

pite

this

, suc

cess

ful a

naly

sis

was

con

duct

ed o

n ge

netic

s, a

ge, a

nd o

tolit

h m

icro

chem

ishy

for

the

SMC

pop

ulat

ion.

G

enet

ic a

naly

sis

cond

ucte

d on

a f

in-c

lip c

olle

cted

fro

m a

sin

gle

adul

t in

199

9 (S

M41

2199

F) r

evea

led

that

the

spe

cim

en c

anie

d a

uniq

ue h

aplo

type

tha

t is

mos

t co

mm

only

fou

nd in

sou

ther

n C

alif

orni

a st

eelh

ead

and

has

neve

r be

en s

een

in a

ny

batcherypopulationofsteelheadorrainbowtrout(Nielsenetal. 19

94).

Thi

sinf

orm

atio

n co

nfir

med

tha

t th

e tr

out

occu

pyin

g SM

C w

ere

wild

fis

h.

Oto

lith

mic

roch

emis

hy

perf

orm

edon

asin

gles

peci

men

col

lect

ed6o

m S

MC

in 1999confirmedthattbeexarnined

fish

was

the

pro

geny

of

an a

nadr

omou

s fe

mal

e st

eelh

ead

(CD

FG s

teel

head

rep

ort,

2000

3; R

iern

an e

ta!.

1994

) and

that

the

coho

rts o

ccup

ying

SM

C w

ere

the

offs

prin

g of

oc

ean-

goin

g ad

ults

. A

ge a

naly

sis

of a

sin

gle

otol

ith in

dica

ted

that

the

fish

wer

e 2+

ye

arso

fage

whe

ncol

lect

edin

199

9. B

ack

calc

ulat

ing

6o

m th

e ag

eat d

isco

very

,it w

as

conf

umed

that

the

anad

rom

ons

stee

lhea

d ad

ults

mos

t lik

ely

ente

red

the

San

Mat

eo

drai

nage

to s

paw

n du

ring

a h

igh

wat

er p

erio

d in

ear

ly s

prin

g 19

97.

Thi

s in

form

atio

n an

d ad

ditio

nal

mon

itori

ne o

bser

vatio

ns w

ere

com

bine

d an

d .,

subm

ittcdasanorig~nalrcp~~ntothcNat~onal

Man

neF

~she

nesS

erv~

ct.(

NM

FS)

hy

the

Cal

ifor

nia D

span

rncn

t ofF

lsh

andG

arne

(Dep

artm

ent)

in F

cbm

ary

2000

. 11 w

asho

ped

that

this

rece

nt in

form

atio

n on

the

new

ly d

isco

vere

d po

pula

tion

ofso

uthe

m s

teel

head

tr

out i

n SM

C w

ould

requ

ire

NM

FS to

re-

eval

uate

the

rece

ntly

des

igna

ted

geog

raph

ic

boun

dary

of t

he e

volu

tiona

ry s

igni

fica

nt u

nit (

ESU

) for

this

spe

cies

. Due

to th

e ra

rity

of

this

occ

urre

nce,

the

Dep

artm

ent a

lso

initi

ated

a m

onito

ring

pro

gram

to

hack

the

stat

us o

f the

ste

elhe

adir

ainb

ow tr

out p

opul

atio

n on

SM

C im

med

iate

ly fo

llow

ing

the

1999

disc

over

y. C

ontin

uedm

onito

ring

bega

n in

Aug

usto

f 19

99 an

d ov

erth

e fol

low

ing

4-ye

ar p

erio

d, a

dditi

onal

inf

orm

atio

n on

gen

etic

s, a

ge a

t gr

owth

, ho

ut b

ehav

ior,

te

mpe

ratu

re c

ondi

tions

and

pop

ulat

ion

stat

us w

as c

olle

cted

. T

he o

bjec

tives

of t

his

stud

y ar

e to

: 1)

des

crib

e th

emon

itor

ing

cond

ucte

d an

d da

ta

gath

ered

on

the

drai

nage

sin

ce th

e re

-dis

cove

ry in

199

9; an

d 2)

to il

lush

ate t

he f

acto

rs

affe

ctin

g th

e su

rviv

al a

nd c

urre

nt st

atus

oft

he so

uthe

m st

eelh

ead/

rain

bow

trou

t in

San

Mat

eo a

nd D

evil

Can

yon

cree

ks.

ME

TH

OD

S A

ND

MA

TE

RIA

LS

A to

tal o

f45

stre

am su

rvey

s wer

e co

nduc

ted

by th

e D

epar

tmen

t fro

m A

ugus

t 199

9 to

Dec

ernb

er20

03.

Sw

eysw

erec

ondu

cted

by D

epar

tmen

tper

sonn

elan

dvol

unte

ers,

an

d st

arte

d at

the

Uni

ted

Stat

es G

eolo

gica

l Sur

vey

(USG

S N

o. 1

1046

300)

gau

ging

st

atio

n on

SM

C to

the

Dev

il C

anyo

n C

reek

con

flue

nce

and

incl

uded

the

entir

e D

evil

Can

yon

Cre

ek d

rain

age.

Thr

ee la

rge

pool

s lo

cate

d on

SM

C, P

ools

1.2

and

3, (

Fig.

1)

'Cal

ifom

iaD

epar

tmen

t of F

ish a

nd G

ame (

CD

FG) 2

000.

Ste

elhe

ad ra

inbo

w tr

out i

n Sa

nMat

eo

Cre

ek, S

an D

iego

Cou

nty,

Cal

ifor

nia.

Rep

ort s

ubm

ined

to th

e N

atio

nal M

arin

e Fi

sher

ies

Figu

re 1

. Map

of s

urve

y ar

ea s

how

iog

Pool

1. 2

and

3, t

empe

ratu

re p

robe

dep

loym

ent a

reas

, ga

ugin

g st

atio

n, a

nd tr

out l

ocat

ions

.

rem

aine

d is

olat

ed f

or m

uch

of t

he s

urve

y pe

riod

and

was

exa

min

ed d

urin

g ea

ch

depa

rtm

ent s

urve

y. A

n ad

ditio

nal 3

.4 km o

f San

Mat

eo C

reek

abo

veth

e Dev

il C

anyo

n C

reek

con

flue

nce

wer

e in

freq

uent

ly s

urve

yed.

Su

rvey

tec

hniq

ues

used

wer

e dr

aina

ge m

appi

ng,

back

pac

k el

ectr

o-sh

ocki

ng

(Sm

ith-R

oot 1

2-B

), sn

orke

ling,

sei

ning

, and

pas

sive

obs

erva

tion.

D

rain

age

map

ping

invo

lved

hik

ing

the

DC

C d

rain

age

to e

valu

ate

habi

tat a

nd to

id

entif

y in

divi

dual

trou

t lo

catio

ns.

Dat

a w

as c

olle

cted

on

fish

bar

rier

s, q

ualit

y of

ha

bita

t, an

d fi

sh p

rese

nce.

E

lect

ro-s

hock

ing

surv

eys w

ere

cond

ucte

d fo

r exo

tic sp

ecie

s rem

oval

and

juve

nile

tr

out d

etec

tion

in a

reas

whe

re se

ioin

gwas

not p

ossi

ble.

Dat

awer

e co

llec

tedo

nspe

cies

ob

serv

ed, w

ater

tem

pera

ture

, and

eff

ort (

seco

nds)

for e

ach

elec

tro-

shoc

king

sur

vey.

T

heus

eoft

heba

ck p

acke

lect

ro-s

hock

erw

as li

mit

eddu

ring

the

surv

ey pe

riod

tore

duce

th

e po

ssib

ility

of

inju

ry to

resi

dent

trou

t. Pr

esen

cela

bsen

ce sn

orke

l sur

veys

wer

e co

nduc

ted

in p

oole

d ar

easw

here

eff

ectiv

e se

inin

g was

diff

icul

t and

whe

re el

ectr

o-sh

ocki

ng w

as in

effe

ctiv

e. S

nork

el su

rvey

s wer

e co

nduc

ted

by a

sin

gle

obse

rver

usi

ng a

n un

derw

ater

div

e lig

ht.

Eac

h su

rvey

cov

ered

th

eent

irep

ool a

nd a

ll fi

sh sp

ecie

s wer

e re

cord

ed. W

hen

trou

t wer

e obs

erve

d, si

ze (t

otal

le

ngth

) was

est

imat

ed a

nd o

ver

all h

ealth

ass

esse

d.

144

CA

LIF

OR

NIA

FIS

H A

ND

GA

ME

Tw

odif

fere

nt t

ypes

of s

eine

s wer

e us

ed to

sam

ple

the

drai

nage

: a 3-m be

ach

sein

e an

d a

12-m

pol

e se

ine.

Sei

nes w

ere

used

for

exo

tic

spec

iesr

emov

al a

nd to

det

erm

ine

if tr

out w

ere

pres

ent.

Pass

ivep

rese

ncel

ahse

nce

shor

e obs

erva

tion

s wer

e co

nduc

ted

on se

vera

locc

asio

ns

to r

ecor

d tr

out

sigh

ting

s an

d ab

unda

nce.

D

ata

wer

e co

llect

ed o

n th

e le

ngth

of

obse

rvat

ion

and

the

spec

ies

enco

unte

red.

A

ll tr

out

sigh

ting

s ob

tain

ed b

y pa

ssiv

e sh

ore

obse

rvat

ions

wer

e vi

sual

ly c

onfi

rmed

with

fol

low

-up

snor

kel s

umey

s the

sam

e da

y. A to

tal o

f 15

fin-

clip

s wer

ecol

lect

ed f

orge

neti

cpur

pose

s fro

mM

arch

199

910 J

une

2000

(Tab

le 1

). E

achs

ampl

ecom

pris

ed o

fa I

-cm

squa

repi

eceo

ffin

tiss

ueex

cise

dfro

m

theuppe~~loheofthecaudalfin an

dpla

ced

on fi

lter

pape

rtod

ry. A

lldr

ieds

ampl

esw

ere

placedinsmallenvelopesfora~~alysis.

A si

ngle

gene

tics

ampl

ewas

sent

torm

itoch

ondr

ial

DN

A (

mtD

NA

) an

alys

is i

n 19

99 a

nd v

erif

ied

the

resi

dent

out

as w

ild f

ish.

Thi

s sp

ecim

enis

desi

gnot

edas

SM

4121

99F

inT

able

1. T

here

mai

ning

14 s

ampl

esw

eres

ent

out f

or m

itoc

hond

rial

DN

A (m

tDN

A)

anal

ysis

in M

arch

of 2

001

and

wer

epor

t on

the

find

ings

of

that

ana

lysi

s in

this

stu

dy (

Tab

le 1

).

Thr

ee te

mpe

ratu

re lo

gger

s (t

wo

Ons

et O

ptic

Sto

wA

way

mod

el n

umbe

r WTA

OB

- 05

+37

and

one

Ons

et O

ptic

Sto

wA

way

Tid

bit m

odel

num

ber

TB

132-

05+3

7) w

ere

depl

oyed

(tw

o on

DC

C a

nd o

ne o

n SM

C)

in A

ugus

t 20

01.

Eac

h pr

obe

gath

ered

lc

mpe

rutu

re d

ata

evcr

y 15

mtn

utes

for

n p

cnod

of

o\e

r I

I ~

nott

tl~

r.

I>au

It~

gg-r

No

471213(DC13Jwasdeployed1nasmallpoolatGPSN 53

476

65.M

' 17

454

85on

DC

C.

appr

oxim

atel

y 1.

6 km

iom

SM

C (F

ig. 1

). T

idhi

tdat

alog

gerN

o. 3

6420

3 (D

C03

) w

as

Tab

le 1

. Tro

ut g

enet

ic s

ampl

es c

olle

cted

on

San

Mat

eo C

reek

and

Dev

il C

anyo

n C

reek

Dat

e L

engt

h mm

Col

lect

ion

Dat

e Sa

mpl

e C

olle

cted

T

L

Loca

tion

Ana

lyze

d

SM41

2199

F S

MlF

SM

2F

SM3F

SM

4F

SM5F

SM

6F

SM7F

SM

RF

SM

IlF

SM

15F

SM 1

6F

SM17

F SM

IBI-

SM19

F

Dev

il C

anyo

n Sa

n M

ateo

Cre

ek

San

Mat

eo C

reek

D

evil

Can

yon

San

Mat

eo C

reek

Sa

n M

ateo

Cre

ek

San

Mat

eo C

reek

Sa

n M

ateo

Cre

ek

San

Mat

eo C

reek

Sa

n M

ateo

Cre

ek

Dev

il C

anyo

n D

evil

Can

yon

Dev

il C

anyo

n D

evil

Can

yon

Dev

il C

anyo

n

May

199

9 M

arch

200

1 M

arch

200

1 M

arch

200

1 M

arch

200

1 M

arch

200

1 M

arch

200

1 M

arch

200

1 M

arch

200

1 M

arch

ZOO

1 M

arch

ZOO

1 M

arch

200

1 M

arch

200

1 M

arch

200

1 M

arch

200

1

deployedinala1gerpoolatGPSN33.47453,W 117.45926onDCC,approximately 0

.8

kmfi

omS

MC

(Fig

. 1). DataloggerNo.4712Sh(SM56)wasdeployedinPool3

onS

MC

(F

ig. I

).

A s

ingl

e ad

ult '

out

was

col

lect

ed in

Jun

e 20

02 o

n D

CC

(de

sign

ated

DC

I) a

nd

exam

ined

to

dete

rmin

e ag

e. T

he f

ish

was

wei

ghed

, m

easu

red,

and

dis

sect

ed.

The

sa

gitt

al o

tolit

hs w

ere

rem

oved

, cl

eane

d, a

nd a

ge d

eter

min

atio

n, u

slng

a d

isse

ctin

g sc

ope,

was

con

firm

ed b

y fo

ur re

ader

s (F

ig. 2

).

RE

SU

LTS

Figu

re 2

. O

tolit

h m

icro

grap

h of

trou

t mlle

cled

on

Dev

il C

anyo

n C

reek

in Ju

ne 2

002.

Age

was

de

term

ined

to b

e 2

+ye

ars o

f ag

e. S

peci

men

was

273

mm

TL

. Pho

to b

y R

. Titu

s

146

CA

LIF

OR

NIA

FIS

H A

ND

GA

ME

Obs

erva

tions

dur

ing

the

surv

ey p

erio

d (A

ugus

t 199

9 to

Dec

embe

r 200

3) re

veal

ed

that

the

trou

t loc

ated

in S

MC

dec

lined

innu

mbe

rs, w

ith n

o bo

ut b

eing

obs

erve

d af

ter

Aug

ust2

000.

InM

ay a

ndJu

ly 2

000,

a to

tal o

f22j

uven

ile

hout

,ran

ging

insi

ze f

rom

60-

81 m

mT

L,w

asdi

scov

ered

occu

pyin

gthe

firs

t 1.2

km

ofD

CC

. Con

tinue

dobs

erva

tions

of

juve

nile

trou

tonD

CC

last

ed th

roug

h Se

ptem

ber2

000.

No

juve

nile

trou

twer

e lo

cate

d in

SM

Cdu

ring

thes

uwey

peri

od.

In A

ugus

t200

1, s

ever

alad

ulttr

out (

200-

250m

mT

L)

wer

e ob

serv

ed in

two

sepa

rate

poo

ls o

n D

CC

, app

roxi

mat

ely

0.8

and

1.6 k

m f

rom

the

SMC

con

flue

nce

(Fig

. 1)

. The

se w

ere

assu

med

to b

e co

hort

s oft

hejn

veni

les

foun

d in

20

00.

Obs

erva

tions

of

adul

ts o

ccup

ying

DC

C a

ppro

xim

atel

y 1.

6 km

up f

rom

the

co

nflu

ence

cont

inue

d thr

ough

Dec

embe

r200

3. T

rout

wer

e fre

quen

tly ob

serv

ed in

DC

C

occu

pyin

g po

ols

duri

ng th

e sp

ring

whe

re t

hey

wer

e pr

evio

usly

abs

ent,

indi

catin

g po

ssib

le d

owns

trea

m m

igra

tion.

W

hile

the

age

at s

ize

of th

e ju

veni

les

foun

d on

DC

C c

ould

not

be

conf

irm

ed, t

he

mea

sure

men

tsof

the

indi

vidu

als a

re w

ell w

ithin

them

axim

um fi

rsty

earg

row

th ra

teof

si

ze-a

t-ti

med

atac

olle

cted

by th

eDep

artm

ent o

fkno

wn-

agej

uven

ile

stee

lhea

d tr

out i

n so

uth-

cent

ral a

nd s

outh

ern

Cal

ifor

nia

coas

t (C

DFG

Ste

elhe

adR

epor

t200

0).

Rep

rodu

ctiv

e ac

tivity

was

obs

erve

d on

DC

C in

Aug

ust 2

001

and

Janu

ary

2002

. T

hree

adu

lt tr

out w

ere

obse

rved

par

ticip

atin

g in

bri

ef s

paw

ning

epi

sode

s on

Dev

il C

anyo

nCre

ek, i

n ap

ool a

ppro

xim

atel

y O

.8la

n fr

om th

e S

anM

ateo

Cre

ekco

nflu

ence

. In

divi

dual

s wer

eusi

ng a

cent

ral b

ould

eras

a st

agin

g ar

eaan

d co

nduc

tingr

epro

dnct

ive

post

urin

g di

rect

ly u

pstr

eam

of t

he b

ould

er.

A re

dd h

ad b

een

cons

truc

ted

adja

cent

to

theb

ould

er an

d in

divi

dual

s wer

e obs

erve

d app

roac

hiig

the r

edd

andr

ubbi

ng th

emse

lves

on

theg

rave

l bot

tom

. T

he re

ddw

as ap

prox

imat

ely

45-6

0 cm

in d

ia

me

te

r

asac

ucnl

ar,s

andy

area

whe

real

l the

leaf

litte

r had

bee

neith

erre

mov

ed o

r cov

ered

. One

ob

serv

atio

n w

as r

ecor

ded

whi

le t

he p

ool

was

bei

ng s

nork

eled

and

ano

ther

was

re

cord

ed fr

om a

rock

out

crop

ping

dir

ectly

abo

ve th

e po

ol.

Bot

h ep

isod

es w

ere

brie

f an

d ac

tivity

cea

sed

once

the

obse

rver

s w

ere

dete

cted

by

the

trou

t. W

hile

this

was

en

cour

agin

g,no

actu

al sp

awni

ng w

as o

bser

ved

and

no n

ew re

crui

tmen

t was

docu

men

ted

for2

001

0120

02.

Mito

chon

dria

1 DN

A (m

tDN

A) w

as su

cces

sful

ly ex

trac

ted f

rom

all f

in-c

lip sp

ecim

ens

and

anal

yzed

acc

ordi

ng to

est

ablis

hed

anal

ytic

al m

etho

ds (N

iels

en e

t al.

1997

). F

ive

ofth

e 19

99sa

mpl

es(S

M3,

SM

4, S

M7,

SM8,andSM1l)showedalackofdifferentiation

betw

een

the

trou

t col

lect

ed, i

ndic

atin

g th

at th

ese

fish

wer

e co

hort

s of

the

prev

ious

ly

analyzedSM412199F(Fl)(Fig. 3

). T

here

mai

ning

four

adul

ts (S

M1,

SM

2, S

M5,

and

SM6)

dif

fere

d in

rela

tedn

ess

from

SM

4 12

199

F an

d w

ere

prob

ably

des

cend

ed fr

om a

se

para

te p

air o

f ana

dmm

ous

adul

ts th

at e

nter

ed th

e C

reek

in e

arly

199

7. A

naly

sis

of

the j

uven

ile s

ampl

es s

how

ed th

at th

ree

of th

e fi

sh (S

M15

, SM

16, a

nd S

M18

) wer

e of

di

rect

des

cent

(F2)

from

SM

4121

99F

(Fl)

. T

he re

mai

ning

two

juve

nile

s (S

M17

and

SM

19)

had

very

div

erge

nt h

aplo

type

s, s

ugge

stin

g th

at m

ore

than

one

res

iden

t sp

awni

ngpa

irbr

ed s

ucce

ssfu

lly in

DC

C in

199

9 (N

iels

en a

nd S

age 2

001 '

)(Fi

g. 3

). N

o us

eabl

emat

eria

l was

obt

aine

dfro

m S

M14

andt

hiss

ampl

ewas

excl

uded

from

ana

lysi

s.

The

tem

pera

hlre

prob

esw

erer

ecov

ered

in J

uly

2002

. Allthreeprobessuccessfully

'Nie

lsen

1.L

andG

.K. S

age.

2001

Mic

rosa

telli

tean

d m

tDN

A a

naly

seso

fSan

Mat

eo C

reek

trout

, 20

01. A

pro

gres

s re

port.

17

pp.

~6

6~

luol(e6eule.pxae.3

oele.4 JeS e

ql d

oe

3u

esa

~o

us, D8lO

Nl8lLfdn Le

~o

a3

Le

plA

ese

pln

old

~

0~

13

"

oA

L~

~

I AD

O b

o qsq .enoP

Ioq PIO

lee6 c,,

F e ,o ~

olle

~d

es

qo

a

ql F

OO

L sol uennl z2 oooz at,\

jo )led

s (ecp spu

l su..,-oa w

e1

3 L

oh

e3

(tnea JO U

npe peleno3e) e ,o 6utB

e 84

1

2002 ~

8.

3

~0,4uo3 IIAOO

-0

doale ndoa ~j Bu ,"led

ju B

u~

~o

lt~o

rll panulluo3

~O

OZ

A~ny pue

he

n b

~ >

ee

l3 ~

oh

ue

3

lleo

do paJeno3slp s~ (2,)

~n

o~

t q

ue

hn

l lo a

m6

lletlts \I woz 853.3

UO

K~

IP~

.*a0

PL

~

~a

e,3

oelcw b

es L

O P

ePaIeP

s (1,) I~

OJI ~

ueptse. PIO Jeah,

2 lo u

o~

leln

lod

IleW

S v :6661 .h

a~

nS

eue

~

pua qs!d 30 lue

lup

ed

ec~

Eu!Jnp yes13 o~

e!,q

UES

uo

pe

pa

lap

148

CA

LIF

OR

NIA

FIS

H A

ND

GA

ME

colle

ct~.

ddat

a fcir

the

I I -m

onth

per

iod

ofde

ploy

mcn

i. T

wuo

fthc

pru

bes(

D('

I3 a

nd

DCU3)r

ccor

dedv

crys

imil

ar~a

d1ng

sfro

mAug

ust2

OOl to

hla

rch2

002

They

reco

rded

m

axim

umte

mpe

ratu

reso

f2 1.

8"C

pCl3

)and

23.1

"C(DC03)andminimumtemperatures

of 7

.8'

C a

nd 5

.8'

C, r

espe

ctiv

ely

(Fig

. 4).

The

ran

ges w

ithin

the

first

7 m

onth

s of

depl

oym

entw

erea

lmos

t ide

ntic

al b

etw

een

DC

13 a

ndD

C03

. For

the l

ast 4

mon

ths o

f de

ploy

men

t. DC

13 re

cord

edm

ore c

onsi

sten

ttem

pera

ture

s, w

ith a

ninc

rcas

e fro

m 1

0. lo

*

U

Devil

Cany

on (D

C13)

Temp

eratur

e Pro

file

L

4

I

Devil

Cany

on (D

COJ) T

empe

rature

Profi

le "2

"

30

1

30 Sa

n Mate

o Cree

k (SM56) Te

mpera

ture P

rofile

cu

LU

'1

', 1" ;: $

,, IL

; 1"

D

0

U

I'

I'

I'

I'

I~

I

1 17

01

09~1

lim

i oli

o2

mm2

051112

071

02 09

102

Figu

re 4

. Tem

pera

ture

pro

files

for

Devil

Can

yon

Cre

ek an

d S

an M

ateo

Cre

ek fr

om

Aug

ust 2

001

to J

uly

2002

.

SO

UTH

ER

N S

TEE

LHE

AD

IRA

lNB

OW

TRO

UT I

N S

AN

MA

TE

OC

RE

EK

CA

LIFO

RN

IA

149

C to

18.

lo C

, with

a d

aily

rang

e of

+I-

0.9

' C

(Fi

g. 4

). D

C03

reco

rded

an

incr

ease

in

tem

pera

ture

inth

atsa

mep

erio

d fr

om 1

1.2'

C t

o 18

.9'C

, w

ithd

aily

rang

es o

f+/-

2.5

'C

IFie

.4).

\- --~

,~

T

he S

M56

tem

pera

ture

pro

be re

cord

ed se

vere

tem

pera

ture

vari

atio

ns fr

om A

ugus

t 20

01 to

Dec

embe

r200

1, w

ith re

adin

gs fr

om 2

8.4'

C

to 7

.9"

C, w

ith so

me

daily

rang

es

shif

ting

+/-

7.5

' C

(Fig

. 4).

Beg

inni

ng in

May

200

2, S

M56

reco

rded

a st

eady

incr

ease

in

tem

pera

ture

, with

dai

ly ra

nges

shi

ftin

g +

/- 1

.4'

C a

nd to

ppin

g ou

t at t

ime

ofre

trie

val

at 2

5.X

°C. T

his w

as in

shar

pcon

tras

tto t

he te

mpe

ratu

rem

axim

ums f

orD

C 1

3 and

DC

03

of 1

8.1"

C a

nd 1

8.9'

C, r

espe

ctiv

ely

atti

meo

fpro

be re

trie

val (

Fig.

4).

Age

-at-

grow

th c

alcu

latio

ns w

ere

perf

orm

ed o

n a

sing

le a

dult

fish

(DC

1) c

olle

cted

in

June

2002

. The

fish

was

rece

ntly

expi

reda

ndac

ompl

ete

wor

k-up

was

perf

orm

ed B

oth

the

righ

t and

left

sag

ittal

oto

liths

wer

e re

mov

ed a

nd a

sin

gle

otol

ith w

as a

ged

by fo

ur

read

ers u

sing

a d

isse

ctin

gmic

rosc

ope (

Fig.

2).

The

fish

was

det

erm

ined

to b

e 2+

yea

rs

ofag

e, an

d w

asa2

73-m

mT

Lfe

mal

e(go

nadw

t. 16

.38g

), w

ith a

body

wei

ghto

f213

.5g.

T

he eg

gs o

fthe

fish

wer

e par

tially

hyd

rate

dupo

nrem

oval

and

appe

ared

ofhi

gh q

ualit

y.

Bot

h lo

bes

of th

e ov

arie

s wer

e ru

ptur

ed a

nd th

e st

omac

h w

as e

mpt

y. G

enet

ic m

ater

ial

was

col

lect

ed, b

ut h

as y

et to

be

anal

yzed

. N

o pa

rasi

tes

wer

e ob

serv

ed, i

nter

nally

or

exte

rnal

ly.

A s

ingl

e ad

ult,

hold

over

trou

t (D

C2)

was

obs

erve

d on

the

conf

luen

ce a

s rec

ently

as

Dec

embe

r 200

3. T

his

spec

imen

was

det

erm

ined

to b

e a

F2

hold

over

fish

due

to it

s si

ze, c

olor

atio

n,an

dloc

atio

non t

hecr

eek.

Thi

s obs

e~at

ione

stab

lish

edan

unin

tem

pted

fi

sh p

rese

nce

on th

e dr

aina

ge s

ince

199

7.

DIS

CU

SS

ION

Alm

ost i

mm

edia

tely

follo

win

g th

e di

scov

ery

of s

outh

ern

stee

lhea

d on

San

Mat

eo

Cre

ek, D

epar

tmen

t sur

veys

beg

an to

reco

rd a

decl

ine i

n tr

out n

umbe

rs to

war

ds th

e en

d of

199

9. O

bser

vatio

ns o

ftro

ut in

an

appa

rent

em

acia

ted

cond

ition

str

ongl

y su

gges

ted

that

reso

urce

com

petit

ion

with

exo

tics w

as im

pa

cti

ng

ut i

va

l Add

ition

ally

, the

re

cord

ed w

ater

tem

pera

ture

with

in S

MC

dur

ing

trou

t pre

senc

e st

rong

ly fa

vore

d th

e ex

otic

spe

cies

ove

r th

e tr

out,

and

prob

ably

con

trib

uted

gre

atly

to

thei

r ev

entu

al

extim

atio

n.

The

disc

over

yofj

uven

iletr

out i

nthe

low

erre

ache

s of

DC

C in

May

andJ

uly

of20

00

beca

me

apiv

otal

obs

erva

tion

duri

ng th

e su

rvey

per

iod.

Thi

s illu

stra

ted

that

eve

n w

ith

~ -

infr

eque

nt a

nd i

nter

mitt

ent

stee

lhea

d tr

out

mig

ratio

n in

to t

he d

rain

age,

suc

cess

ful

resi

dent

(F

l) r

epro

duct

ion

coul

d re

sult.

T

hese

obs

erva

tions

als

o co

nfir

med

tha

t ad

equa

te re

side

nt sp

awni

ng h

abita

t doe

s exi

st in

DC

C, a

ndgi

vent

he pr

oper

con

ditio

ns,

resi

dent

spa

wni

ng c

ould

occ

ur. T

his t

ribu

tary

is c

ompl

etel

y fr

ee o

f exo

tic fi

sh sp

ecie

s an

d ho

lds p

rom

isin

g tr

out h

abita

t onl

y a

shor

t dis

tanc

e fr

om th

e SM

C.

Add

ition

ally

, te

mpe

ratu

re s

trat

ifie

dpoo

ls, d

eep

enou

ghan

dcol

d en

ough

to su

ppor

ttro

utye

ar-r

ound

ar

e re

adily

ava

ilabl

e in

the

drai

nage

. T

hege

neti

c an

alys

is w

as c

ruci

al in

not o

nly

esta

blis

hing

thel

inea

ge o

fthe

sam

pled

tr

out w

ithin

the

drai

nage

, but

als

o pr

ovin

g a

conn

ectio

n be

twee

n th

e tr

out l

ocat

ed in

bo

th d

rain

ages

. The

trou

t fir

st a

naly

zed

(SM

412

199F

) was

col

lect

ed in

DC

C a

nd th

e

150

CA

LIF

OR

NIA

FIS

H A

ND

GA

ME

conf

umed

coho

rts(

SM

4, S

M7,

SM

8,an

dSM

ll)w

erea

ll c

olle

cted

inS

MC

,ind

icat

ing

eith

er u

pstt

eam

or d

owns

irea

mm

igra

tion

of t

here

side

nts.

Sin

ce w

e ob

sew

edtr

out i

n de

clin

ing

heal

th, c

o-oc

cuni

ngw

ith

exot

ics i

n SM

C, t

he s

urve

y ob

serv

atio

ns p

rovi

de

stro

ng e

vide

nce t

hat d

owns

trea

m m

igra

tion

of t

he re

side

nts

from

DC

C to

SM

C li

kely

oc

curr

ed.

The

posi

tive

iden

tifi

cati

on of

dire

ct d

esce

nden

ts (S

arnp

lesS

M15

, SM

16, a

ndS

MI 8

) fr

omth

epre

viou

sly

sam

pled

SM

4 12

199F

indi

cate

stha

t thc

trou

lpop

ulat

ion

size

onth

e dr

aina

ge i

s ex

trem

ely

smal

l. T

his

is a

lso

the

firs

t ev

iden

ce s

uppo

rtin

g su

cces

sful

re

pro

du

ctio

nan

dsu

~iva

lofF

2 off

spri

ngfr

omth

is F

1 co

hort

(SM

4 12

1YY

F)(T

ahle

I).

Sin

ce th

e tw

o re

mai

ning

juve

nile

sam

ples

wer

e sh

own

to b

e de

rive

d fr

om a

yet

un

sam

pled

res

iden

t pai

r, w

e co

nclu

ded

that

add

itio

nal,

undo

cum

ente

d re

side

nt f

ish

may

sti

ll o

ccup

y th

e dr

aina

ge, f

urth

er e

leva

ting

pop

ulat

ion

num

bers

. T

he te

mpe

ratu

re d

ata

obta

ined

firo

m th

e pr

obes

cle

arly

sho

ws t

hat D

evil

Can

yon

mai

ntai

nsam

orec

onsi

sten

t and

pref

eren

tial

tem

pera

ture

pro

file

for s

outh

emst

eelh

eadl

ra

inbo

w tr

out s

urvi

val t

han

port

ions

of

San

Mat

eo C

reek

(Fig

. 4).

Sou

them

race

s of

st

eelh

ead

have

evo

lved

a m

uch

high

er t

oler

ance

to

high

tem

pera

ture

s an

d lo

w

diss

olve

d ox

ygen

lev

els

than

is

gene

rall

y th

ough

t su

itab

le f

or ju

veni

le s

alm

onid

s (G

reen

woo

d 19

88),

and

the

pre

ferr

ed w

ater

tem

pera

ture

for

var

ious

lif

e st

ages

of

stee

lhea

d is

wel

ldoc

umen

ted(

Bov

ee 1

978:

Rei

sera

ndB

jom

n 1 9

795:

Bel

l 198

6). W

hile

th

is a

dapt

atio

n to

adv

erse

wat

er c

ondi

tion

s may

ass

ist i

n so

uthe

rn s

tecl

head

surv

ival

, te

mpe

ratu

re st

abil

ity

and

redu

ced

dail

y ra

nge

shif

ts w

ould

bem

ore

favo

rabl

e fo

r tro

ut

occu

pyin

g th

is d

rain

age.

B

oth

SM

C a

nd D

CC

exh

ibit

ide

al s

outh

em s

teel

head

life

his

tory

tem

pera

ture

s (M

cEw

anan

dJac

kson

199

66) fo

rapo

rtio

n of

the y

ear,

but

, dur

ing

the

sum

mer

, sec

tion

s of

the

drai

nage

expe

rien

ce su

rfac

e w

ater

tem

pera

ture

s in

ex

ce~

sof2

6.7

~C

, w

ell a

bove

su

itab

le sa

lmon

id p

refe

renc

e. T

empe

rntu

re st

rati

fica

tion

occ

urs t

hrou

ghou

t the

SM

C

drai

nage

and

has b

een

docu

men

ted

inpo

olso

ccup

ied

by tr

out.

How

ever

, dur

ing

drye

r ye

ars,

poo

l str

dtif

icat

ion

and

surv

ivab

le te

mpe

ratu

res f

or s

alm

onid

s bec

omes

lim

ited

. T

he p

robe

dat

a su

gges

ts th

at th

e ov

er-s

umm

erin

g ha

bita

t ava

ilab

le in

Dev

il C

anyo

n pr

ovid

es a

mor

e st

able

tem

pera

ture

env

iron

men

t fo

r st

eelh

ead

sust

aina

bili

ty a

nd

surv

ival

. T

he c

olle

ctio

n of

the

sing

le d

ead

indi

vidu

al (D

C 1

) on

DC

C d

urin

g th

e su

mm

er o

f 20

02 en

able

dus t

onot

onl

y co

nfn

n th

e ag

eoft

he in

divi

dual

s tha

twer

e cu

rren

tly b

eing

m

onit

ored

on

DC

C, b

ut a

lso

allo

wed

us

to e

xam

ine

the

repr

oduc

tive

sta

tus

of th

e co

llect

ed s

peci

men

. The

fis

h w

as 2

+ ye

ars

of a

ge,

cnn

fmin

g th

at t

he l

ike-

size

d in

divi

dual

s occ

upyi

ng D

CC

wer

e ind

eed

coho

rts o

f the

2000

jwen

ile

grou

p dis

cove

red

in th

e lo

wer

por

tion

oft

he d

rain

age

inM

ay a

nd J

uly

ofth

at y

ear.

Upo

n di

ssec

tion

, no

anom

alie

s wer

e di

scov

ered

. The

wei

ght o

f the

two

ovar

ies m

ade

up o

ver 7

.5%

of t

he

'Rei

ser,

D.W

., an

d T.

C. B

jom

. 197

9. H

abita

trequ

irem

ents

ofan

adro

mou

s sal

mon

ids.

USD

A,

Fore

st S

ervi

ce, P

acifi

c N

onha

est

Fore

st a

nd R

ange

Exp

erim

enta

tion

Stat

ion,

Por

tland

, O

rego

n, G

ener

al T

echn

ical

Rep

ort P

NW

-96,

54

pp.

WcE

wan

,D.a

ndT

.A.Ia

ckso

n 1996.SteeBeadrestorationandmanagementplanforCalifomia.

Cal

iforn

ia D

epar

tmen

t of F

ish

and

Gam

e, S

acra

men

to, C

A.

body

wei

ght

of th

e fi

sh a

nd t

he e

ggs

look

ed t

o be

par

tially

hyd

rate

d in

lif

e. T

his

indi

cate

dtha

t thi

s fis

h co

uld

have

par

tici

pate

din

spaw

ning

activ

ity d

urin

g sp

ring

2002

, gi

ven

the

oppo

rtun

ity. T

here

was

no o

utw

ard

indi

catio

n of

why

the

fish

die

d. H

owev

er,

the

pool

inw

hich

the

fish

was

col

lect

ed, h

ad a

wat

er te

mpe

ratu

re o

f25'

C a

t the

tim

e of

co

llect

ion,

and

it is

like

ly th

e fi

sh s

uccu

mbe

d to

dep

lete

d di

ssol

ved

oxyg

en le

vels

in

the

shal

low

, ove

rhea

ted

pool

. T

he a

dditi

onal

gen

etic

, ag

e, a

nd m

onito

ring

inf

orm

atio

n co

llect

ed d

urin

g th

is

surv

ey p

erio

dcla

rifi

esth

e seq

uenc

eofe

vent

s fo

r the

pop

ulat

iono

f ste

elhe

adhi

nbow

bo

ut o

n th

e Sa

n M

ateo

Dra

inag

e (F

ig. 3

). B

ack

calc

ulat

ions

of t

he in

divi

dual

s age

d in

19

99 co

nfir

m th

at th

e an

adro

mou

s ad

ults

(P

I) en

tere

d th

e dr

aina

ge in

the

earl

y sp

ring

19

97 to

spa

wn.

Gen

etic

ana

lysi

s of

sam

ples

SM

I, S

M2,

SM

5, a

nd S

M6

conf

rm th

e pr

esen

ceof

anad

diti

onal

anad

rom

ousp

airi

nthe

dra

inag

ein

1997

.No f

ish

wer

edet

ecte

d du

ring

aD

epar

hnen

tsur

vey

on S

anM

ateo

Cre

ekin

199

8. In

the

follo

win

g ye

ar, a

smal

l po

pula

tion

of h

out

(FI)

was

dis

cove

red

occu

pyin

g Sa

n M

ateo

Cre

ek.

All

trou

t ob

serv

ed w

ere

of a

sin

gle

age

clas

s (2

+ ye

ars)

, ind

icat

ing

they

wer

e th

e of

fspr

ing

of

a si

ngle

, rep

rodu

ctiv

e ev

ent.

In 2

000,

juve

nile

trou

t (F

2) w

ere

disc

over

ed in

the

low

er

reac

hes o

fDev

il C

anyo

nCre

ek. G

enet

ic a

naly

sisl

inke

dthe

se f

ish

to th

eF1

popu

latio

n,

som

e di

rect

ly d

esce

nded

from

the

firs

t fis

h an

alyz

ed (S

M41

2199

F). T

he p

rese

nce

of

sub-

adul

ts o

n th

e dr

aina

ge in

Nov

embe

r 200

0 su

gges

ts th

at th

ey w

ere

mat

urin

g F

2's.

A

ge a

naly

sis o

f a s

ingl

e ad

ult (

DC

I) c

olle

cted

in Ju

ne 2

002

conf

rms

that

a fe

w o

f the

ad

ult f

ish

curr

ently

occ

upyi

ng D

CC

are

mat

ure

F2'

s (F

ig. 3

). S

urve

ys c

ondu

cted

on

SMC

and

DC

C in

200

1 an

d 20

02 re

veal

ed n

o ne

w re

crui

tmen

t dur

ing

that

tim

e. T

he

disc

over

y of

a 3

.5-y

ear-

old

hold

over

fish

(DC

2) in

DC

C in

Dec

embe

r 200

3 pr

ovid

es

evid

ence

that

ther

e ha

s bee

n an

uni

nter

rupt

ed tr

outp

rese

nce

on th

e dr

aina

ge s

ince

the

anad

rom

ous

adul

ts e

nter

ed S

MC

dur

ing

the

spri

ng o

f 19

97 to

spa

wn.

W

hile

the

timel

ine

oftr

out p

rese

nce

on th

e dr

aina

ge c

anbe

firm

ly es

tabl

ishe

d w

ith

the

evid

ence

gat

here

d du

ring

the

stud

y pe

riod

, som

e qu

estio

n ca

n be

rais

ed o

n w

here

th

e or

igin

al s

teel

head

adu

lts s

paw

ned

in 1

997.

Sur

veys

con

duct

ed in

199

5,19

96, a

nd

1997

byth

eUni

tedS

tate

sFis

hand

Wild

life S

ervi

ce(U

SFW

S) an

daD

epar

tmen

tsur

vey

cond

ucte

d in

199

8 fa

iled

to d

etec

t hou

t on

SM

C.

If a

nadr

omou

s ad

ults

ent

ered

the

drai

nage

and

spa

wne

d in

San

Mat

eo C

reek

in

1997

, you

ng-o

f-th

e-ye

ar in

divi

dual

s sh

ould

hav

e be

en d

etec

ted

in fa

ll 19

97 by

USF

WS

pers

onne

l and

yea

rlm

g in

divi

dual

s sh

ould

hav

e be

ende

tect

ed in

199

8 by

Dep

artm

ent p

erso

nnel

. All

surv

eys i

nclu

dedt

he

stre

am p

ortio

n fr

om th

e U

SGS

gaug

ing

stat

ion

to a

bove

the

DC

C c

onfl

uenc

e, bu

t did

no

t inc

lude

DC

C. S

ince

the

age o

f the

199

9 ind

ivid

uals

has

bee

n co

nfir

med

atZ

+ye

ars

of a

ge a

nd th

e fi

sh w

ere

all c

ohor

ts, t

hey

had

to b

e pr

esen

t on

the

drai

nage

dur

ing

the

1997

and

1998

surv

eys.

Sin

ceth

enps

trea

mm

igra

tion

oppo

~it

iesf

rom

SM

C

toD

CC

ha

ve b

een

extr

emel

y lim

ited

sinc

e 19

99, a

nd h

out w

ere

abse

nt in

SM

C w

hen

thos

e op

port

uniti

es e

xist

ed, w

e ca

n co

nclu

de t

hat

all

trou

t ob

serv

ed d

urin

g th

e or

igin

al

disc

over

y in

199

9, m

igra

ted

dow

nstr

eam

from

DC

C in

to S

MC

. We

can

also

conc

lude

th

at th

e in

divi

dual

s dis

cove

red

in 1

999 w

ere

atte

mpt

ing

to e

mig

rate

out

ofD

CC

at t

he

tim

e of

dis

cove

ry, a

s sev

eral

oft

hem

wer

e ob

serv

ed in

the

silv

ery,

smol

tific

atio

n st

age

whe

n ca

ptur

ed.

The

im

pact

s of

exo

tic f

ish

com

petit

ion

and

pred

atio

n on

nat

ive

fish

is

wel

l

152

CA

LIF

OR

NIA

FIS

H A

ND

GA

ME

docu

men

ted

and

whi

le d

irec

t com

petit

ion

is d

iffi

cult

t~ q

uant

ify,

the

obse

rvat

ion

of

resi

dent

trou

t on

SMC

in a

n un

heal

thy

stat

e co

-occ

unin

g w

ith n

onna

tives

sug

gest

s th

at tr

out s

urvi

val i

ssev

eral

ly h

inde

redb

ythe

con

stan

tpre

senc

eofe

xoti

c fi

shsp

ecie

s.

Exo

tic fi

sh sp

ecie

s (la

rgem

outh

bass

, gre

en su

nfis

h, b

lueg

ill a

ndbl

ack

bullh

ead)

hav

e be

en p

rese

nt in

gre

at n

umbe

rs w

ithin

the

San

Mat

eo C

reek

dra

inag

e fo

r man

y ye

ars

(USF

WS

stat

us re

port

, 19

98; W

oelf

el 1

991 ')

and

hav

e he

en s

how

n to

hav

e a

stro

ng

com

petit

ivee

dgeo

verr

esid

enttr

out.

Gre

en su

nfis

h ha

vebe

en fo

und

to fe

edon

juve

nile

troutandout-competeadultsteelhead f

orbe

nthi

c fo

od(S

wif

t 197

58;G

reen

woo

d 198

8).

Lar

gem

outh

bas

s ta

ke o

ver a

s top

pre

dato

r in

the

habi

tat t

hey

occu

py n

nd c

an d

irec

tly

pred

ate

stee

lhea

d (S

toud

er e

t al.

199

7).

Oth

er st

udie

s hav

e fou

nd th

at co

mpe

titio

n be

twee

n in

trod

uced

, wan

n w

ater

exot

ics

and j

uven

ile s

teel

head

, whe

n w

ater

con

ditio

ns a

re w

arm

, fav

ored

the

exot

ics

(Ree

ves

1985

9). L

ater

stu

dies

infe

rred

that

com

petit

ion

betw

een

exot

ic sp

ecie

s an

d st

eelh

ead

was

lim

iting

prod

uctio

n of

stee

lhea

din

som

e Um

pqua

Riv

er, O

R.tr

ibut

arie

s(Fo

ntai

ne

1988

'").

Whi

le ex

otic

fish

pres

ence

may

hav

epla

ycd

som

crol

e in

ste

elhe

adtr

outd

eclin

e onSMC,thecombinationofahigherwatertemperature a

ndli

mit

edw

ater

supp

ly li

kely

co

ntri

bute

d.

A p

ortio

n of

the

inf

orm

atio

n co

llect

ed d

urin

g th

is 4

-yea

r m

onito

ring

pro

gram

pr

ovid

ed N

MFS

with

eno

ugh

data

to

re-e

valu

ate

the

ESU

geo

gaph

ic u

nit

for

the

enda

nger

ed s

outh

ern

stee

lhea

d tr

out

esta

blis

hed

in 1

997.

On

May

200

2, N

MFS

pu

blis

hed

thei

r fin

al ru

le fo

r the

rang

e ex

tens

ion

for e

ndan

gere

d st

eelh

ead

in s

outh

ern

Cal

ifom

ia. C

iting

thee

xten

sive

mon

itori

ng in

fort

natio

ncol

lect

edby

the

Dep

arhn

enta

nd

then

ew g

enet

ic an

alys

is co

nduc

ted

by D

r. Je

nnif

erN

iels

en, t

heN

MF

S c

oncl

uded

that

th

e 0. m

ykis

s pop

ulat

ion

in S

an M

ateo

Cre

ek is

par

t of t

he li

sted

sou

ther

n C

alif

omia

st

eelh

ead

popu

latio

n an

d w

orth

y of

pro

tect

ion.

Als

o ci

ting

the

San

Mat

eo C

reek

po

pula

tion,

NM

FS d

ecid

edno

t to

delin

eate

a sp

ecif

ic st

ream

as t

he so

uthe

rn h

ound

aty

as it

hadi

n 19

97. I

nste

ad,th

e fi

nalr

ule

stat

es th

atth

elis

tedo

. myk

iss p

opul

atio

n ex

tend

s Fr

omth

e San

taM

aria

Riv

er to

the s

outh

ern

exte

nt o

fits

rang

e. T

hisp

rovi

des a

dditi

onal

pr

otec

tion

for

futu

re d

isco

veri

es w

ithin

the

ent

ire

enda

nger

ed s

outh

em s

teel

head

ra

nge.

The

indi

vidu

als c

urre

ntly

occ

upyi

ng th

e S

an M

ateo

Cre

ek d

rain

age

repr

esen

t th

e so

uthe

rn m

ost d

ocum

ente

d po

pula

tion

of 0

. myk

iss.

It

is c

lear

that

two

defi

nitiv

e pr

oces

ses

com

bine

to in

flue

nce

the

surv

ival

of

the

sout

hern

stee

lhea

d tr

out p

opul

atio

n on

be

San

Mat

eoD

rain

age;

wat

er a

vaila

bilit

y an

d

'Woe

lfel.

D.

1991

. The

rest

orat

ion

of S

an M

ateo

C~

ck

:

A f

easi

bili*

stu

dy fo

r a

sout

hern

C

alifo

mia

stee

lhea

d fi

sher

y. M

S. T

hesi

s, C

alifo

mia

Sta

te U

nive

rsity

, Ful

lerto

n B

Swift

,C.C

.,A.W

. Wel

ls,a

ndJ.

S.D

iana

. 197

.5. Surveyofthefreshwaterfishesandtheuhabitats

in th

e co

asta

l dra

inag

es o

f sou

ther

n C

alifo

mia

. Nah

lral

Hist

ory

Mus

eum

of h

a Ang

eles

C

ount

y.Fi

nal R

epor

t toCalifomiaDepamnentofFishandGame,InlaodFisheries D

ivis

ion.

36

4 pp

. gR

eeve

s, G

. 19

85. C

ompe

titio

n be

twee

n re

dsid

e sh

iner

s an

d st

eelh

ead

trout

juve

nile

s in

the

U

mpq

ua R

iver

. Dis

serta

tion,

Ore

gon

Stat

e U

nive

rsity

, Cor

valis

, Ore

gon

'OFo

ntai

ne, B

. 19

88. A

n as

sess

men

t of

habi

tat

enha

ncem

ent m

easu

res

and

fact

ors

limiti

ng

prod

uctio

n of

ste

elhe

ad tr

out i

n tri

buta

ries t

o th

eUrn

pqua

Riv

er. M

.S. T

hesi

s, O

rego

n St

ate

Uni

vers

ity, C

orva

lis, O

re.

the

pres

ence

or a

bsen

ce o

fexo

tic

fish

spec

ies.

For

the

last

60

year

s, M

alin

e bas

e C

amp

Pend

leto

n ha

sbee

n pu

mpi

ng g

roun

d w

ater

from

the

aqui

ferb

enea

th th

e S

MC

drai

nage

. W

hile

str

eam

con

ditio

ns a

re c

urre

ntly

cap

able

of s

uppo

rtin

g a

stee

lhea

d po

pula

tion,

al

tern

ativ

es to

redu

ce o

r elim

inat

e th

is p

ress

ure

on th

e re

sour

ce c

an o

nly

bene

fit t

he

trou

t. A

dditi

onal

eff

orts

are

nee

ded

to s

eek

an a

ccep

tabl

e an

d ef

fect

ive

met

hod

for

cont

rolli

ng ex

otic

fish

spec

ies o

n th

e dr

aina

ge.

Reg

ardl

ess o

fthe

met

hods

em

ploy

ed,

this

und

erta

king

can

not b

e su

cces

sfU

l in

the

long

-ter

m u

nles

s re

-inf

esta

tion

from

the

sour

ce is

con

trol

led,

ifth

e so

urce

stil

l exi

sts.

Cur

rent

ly, t

he p

opul

atio

ns o

f exo

tic fi

sh

spec

ies w

ithin

the

dra

inag

e ar

e se

lf-s

usta

inin

g an

d an

nual

rep

opul

atio

n of

the

cree

k oc

cur f

rom

adu

lts w

ithin

the

cree

k.

Eve

n th

ough

the

San

Mat

eo d

rain

age

stee

lhea

dira

inbo

w h

out h

ave

extr

emel

y lo

w

popu

latio

nnum

bers

bas

edon

Dep

arhn

ent s

urve

ys, t

heir

cont

inue

dsur

viva

l ine

xtre

mel

y ha

rsh

cond

ition

s mak

es th

eir p

rese

rvat

ion

even

mor

e im

port

ant.

All

juve

nile

coa

stal

ra

inbo

w t

rout

hav

e th

e po

tent

ial

to e

mig

rate

fro

m t

heir

coa

stal

str

eam

and

bec

ome

stee

lhea

d ir

resp

ectiv

e of t

heir

par

enta

ge, a

nd th

eref

ore

are

extr

emel

y im

port

ant t

o th

e pe

rsis

tenc

e of

the

popu

latio

n (B

ehnk

e 19

92).

Thi

s pol

ymor

phic

pop

ulat

ion

stru

ctur

e al

low

s per

sist

ence

in a

n en

viro

nmen

t tha

t is f

requ

ently

sub

optim

al an

d po

pula

tions

of

this

type

may

be

nece

ssar

y fo

r the

long

-ter

m p

ersi

sten

ce o

f the

pop

ulat

ion

(Joh

nson

19

85, T

itus

and

Mos

egaa

rd 1

992,

Nor

thco

te 1

997)

. O

ften

spe

cies

occ

upyi

ng th

e m

argi

ns o

fthe

irra

nge

bene

fit f

rom

apo

lym

o~ph

ic life h

isto

ry w

here

con

ditio

nsm

ay b

e un

stab

le. T

his

life-

hist

ory

plas

ticity

, in

a d

rain

age t

hat e

xper

ienc

es u

nrel

iabl

e st

ream

fl

ow fo

r im

mig

ratin

g ad

ults

and

em

igra

ting

smol

ts, a

nda

cons

tant

exo

tic p

rese

nce,

is

undo

ubte

dly

the

reas

on s

outh

ern

stee

lhea

dhai

nbow

trou

t con

tinue

to o

ccup

y th

e Sa

n M

ateo

Cre

ek d

rain

age.

AC

KN

OW

LED

GM

EN

TS

Dr. J.Nielsenprovidedessentialcommentsonthe g

enet

ic po

rtio

noft

hism

anus

crip

t. I a

m th

ankf

ul to

all t

he re

view

ers t

hat a

ssis

ted

in th

e ed

iting

of t

he te

xt a

nd to

C. M

iller

fo

r pro

vidi

ng a

ssis

tanc

e on

the

figu

res.

LIT

ER

AT

UR

E C

ITE

D

Beh

nke,

R.J

. 19

92. N

ativ

e ho

ut o

f w

este

rn N

orth

Am

eric

a. A

mer

ican

Fis

herie

s So

ciet

y,

Mon

ogra

ph N

o. 6

. 275

pp.

B

ell,

M.C

. 198

6. F

ishe

ries h

andb

ook

of e

ngin

eerin

g req

uire

men

ts an

d bi

olog

ical

crite

ria. F

ish

PassageDevelopmentandEvaluationPmgram,U.S.Army Cor

psof

Eng

inee

rs,N

orth

Paci

fic

Div

isio

n. P

ortla

nd, O

rego

n, 2

90 p

p.

Bov

ee,

K.D

. 19

78. P

roba

bilit

y-of

-use

crit

eria

for

the

fam

ily S

alm

onid

ae. I

nstre

am F

low

In

form

atio

n Pa

per 4

, Uni

ted

Stat

es F

ish

and

Wild

life

Serv

ice,

FW

SIO

BS-

78/0

7. 7

9 pp

. G

reen

woo

d, K

.R.

1988

. A c

once

ptua

l dra

ft: C

me

l R

iver

Wat

ersh

ed M

anag

emen

t Pla

n.

Mon

tere

y Pe

nins

ula

Wat

er D

istri

ct

John

son,

B. 1

985.

Life

his

tory

pat

tern

s ofr

esid

ent a

nd se

a-ru

n m

igra

nt b

row

n tro

ut in

Now

ay.

Tran

sact

ions

of th

e A

mer

ican

Fis

herie

s Soc

iety

. 1 1

4:18

2-19

4.

154

CA

LIF

OR

NIA

FIS

H A

ND

GA

ME

Nie

lsen

, J.L

., C

.A.G

an, a

nd W

.K. T

hom

as.

1994

. Dif

fere

nces

in g

enet

ic d

iver

sity

for

mtD

NA

be

twee

n ha

tche

ryan

dwild

popu

latio

nsof

Onc

orhy

nchw

.Can

adia

nJou

mal

ofFi

sher

iesa

nd

Aqu

atic

Sci

ence

s, 5

1 (S

uppl

1):

290-

297.

N

orth

cote

. T.G

. 19

97. Why s

ea ru

n? A

n ex

plor

atio

n in

to th

e m

igra

tory

lres

iden

cy s

pect

rum

of

coas

tal c

utth

roat

trou

t. Pa

ges

20-2

6 in

: J.

D. H

all,

P.A

. Bis

son,

and

R.E

. Gre

ssw

ell,

edit

ors.

Se

a-ru

n cu

tthro

at tr

out:

biol

ogy,

rnan

agm

emen

t and

futu

re c

onse

rvat

ion.

Ore

gon

Cha

pter

, A

mer

ican

Fis

heri

es, C

owal

lis.

Pag

es 2

0-26

. Rieman,B.E.,D.L.MyersandR.L.

Nie

lsen

. 199

4Use

ofot

olit

hmic

roch

emis

t1yt

odis

crim

inat

e O

ncor

hvnc

hus

nerk

a of

resi

dent

and

ana

drom

ous o

rim

. Can

adia

n Jo

urna

l of F

ishe

ries

and

-

Aqu

atic

Sci

ence

s, 5

1 :68

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Stou

der,

D.J

.,P.A

. Bis

son,

and

R.J

.Nai

man

,edi

tors

. 1997.Pacificsalmanandtheirecosystems:

stat

us a

nd f

utur

e op

tions

. Cha

pman

and

Hal

l, N

ew Y

ork.

T

itus

, R

.G.

and

H.

Mos

egaa

rd.

1992

. Flu

ctua

ting

recr

uitm

ent

and

vari

able

lif

e hi

stor

y of

m

igra

tory

bro

wn

trou

t, Sa

lmo

mtt

a L

., in

a s

mal

l, un

stab

le s

trea

m. J

oum

al o

f Fi

sher

ies

Bio

logy

.41:

239-

255.

Rec

eive

d: 1

3 Se

ptem

ber 2

002

Acc

epte

d: 3

Sep

tem

ber

2003