Demographics of kelp bass in the Santa Barbara Channel

J. Wilson WhiteJennifer E. Caselle

Dept. of EEMB Marine Science InstituteUC Santa Barbara

Naples

Scorpion

Middle

Gull Isle

Yellow-banks

ForneyPelican

Hazards

Cojo

Valley

Harris Pt.

Crook Pt.

Years of Data

36

2

Study Sites

East

PISCO

Algae/invertebrate transect distribution

Coastline

5 m

15 m

Annual surveyWithin-site sampling design

Fish transects

Algae transects

2 m

2 m

30 m

1. Count fish2. Estimate sizes

- total length (to nearest cm) 3. Three levels in water column

(where canopy present)- bottom- midwater- surface canopy

Fish Surveys: Kelp Surveys:1. Count # kelp stipes

Estimating Larval Supply: SMURFsStandardized Monitoring Unit for Recruitment of Fishes

Giant Tuffy

Sampling Schedule

J A S O N D JJ

SMURFs(biweekly per site)

Community Surveys(once per site)

settlers

recruits + all adult fish

kelp abundance

M

SMURF-YOY relationship

J A S O N D JJ

SMURFs(biweekly per site)

Community Surveys(once per site)

M

Only used SMURF data up to date of benthic survey

Larval supply - recruitment relationship:dependent on kelp abundance

ln(recruits) = 0 + 1ln(larval supply) + 2kelp + 3kelpln(larval supply)

Estimating Post-settlement Survivorship

YOY

1 yr old

1+ yr old

juvenile survival

adultsurvival

year t year t+1

YOY = Young-of-the-year = ‘recruits’(fish that have settled recently and are counted in benthic surveys)

Estimating Young-of-Year (YOY) survivorship

J A S O N D JJ

SMURFs(biweekly per site)

Community Surveys(once per site)

M

Entire YOY cohort not sampled by benthic surveys

settlers (from SMURF)

1 yr olds(from surveys)

Juvenile Survivorship

YOYs on transect (predicted from

recruitment regression)

ln(1 year olds) = 0 + 1ln(YOY density) + 2kelp

settlers (from SMURF)

1 yr olds(from surveys)

Juvenile Survivorship

YOYs on transect(predicted)

Recruits = 1(SMURF settler densitykelp)1 yr olds = Recruits/(1+Recruits/2)

fit parameters for both transitions

1+ yr olds(from surveys)

Adult Survivorship

1 yr olds & 1+ yr olds(from surveys)

Nt+1 = Nte-( +

adults +

adults kelp)

Large-scale patterns:

Adult kelp bass density is

-positively correlated with larval supply

-negatively correlated with kelp

Large-scale patterns of larval supply & kelp density