Regional differences in Pacific sardine

populations determined by otolith morphology

Barbara Javor, SWFSC

Pacific sardine migrations

Felix-Uraga et al., 2005

Humboldt Bay

Monterey

Pt Hueneme

San Diego

Ensenada

Gulf of CA

Bahía MagdalenaSurvey collections

Port & bait samples

1. Coastwide similarities and differences in juvenile otoliths (late age-0 to age-2)

2. Does temperature play a role?

3. Northern vs. Southern California vs. Ensenada: year-to-year trends

4. Offshore, adult sardine from spring surveys

4 Inter-related Otolith Research Studies

What can sardine otoliths tell us?

• Age

• Regional and temporal characteristics– Morphometric features [image analysis]

– Temperature (18O in CaCO3) [mass spec]

• Collection of >5700 otoliths from most of their range

• Principal components analysis showed length, area, perimeter, and weight were the most important factors

• Analysis of “Perimeter-Weight Profiles” (PWP’s) based on weight-length, perimeter-length, and perimeter-area relationships of “average” otoliths

• Compared regions by age (size) and date

Morphometric Analysis

y = 2.6808x + 0.118

R2 = 0.9749

3

7

11

15

1 2 3 4 5Length, mm

Pe

rim

ete

r, m

mA

y = -0.225x2 + 3.1559x + 1.9071

R2 = 0.968

3

7

11

15

0 1 2 3 4 5Area, mm2

Pe

rim

ete

r, m

m

B

Calculating perimeter from length or area

y = 0.1054x2.2429

R2 = 0.9664

0

1

2

3

4

1 2 3 4 5Length, mm

We

igh

t, m

g

Cy = 0.2709x2 - 0.6052x + 0.6084

R2 = 0.9466

0

1

2

3

4

1 2 3 4 5Length, mm

We

igh

t, m

g

D

Calculating weight from length

Perimeter-weight profiles of sardine otoliths

N. California to the Gulf of CaliforniaAge 1-2 (n= number of otoliths)

0%

20%

40%

60%

80%

Humbo

ldt

Mon

tere

y

Pt Huen

eme

San D

iego

Ensen

ada

BMag G

ulf

Perimeter (area)Perimeter (length)Weight (length)

61836

522

15881588

15889

328

1. Coastwide survey

There is a strong correlation between temperature vs. otolith perimeter and weight in the San Diego population of sardines

R2 = 0.9086

-0.5

-0.3

0.0

0.3

0.5

-0.5 0.0 0.5 1.0 1.5

Difference in Perimeter from Pop. Avg (mm)

18O

, ‰

War

mer

A

Col

der

Smooth

Highly Lobed

Lobed vs. Smooth Perimeter

R2 = 0.9955-0.5

-0.3

0.0

0.3

0.5

-0.3 -0.1 0.1 0.3

Difference in Weight from Pop. Avg (mg)

18O

, ‰

B

War

mer

Col

der

Very Light

Heavy

Light vs. Heavy Weight

2. Temperature

PWP’s of age 0-1 cohorts, 2006-7: Monterey, Port Hueneme, and San Diego

0%

20%

40%

60%

80%

6 12 18 24

MontereySan DiegoPt Hueneme

2006 2007

A

June Dec June Dec

Perimeter based on area

0%

20%

40%

60%

80%

6 12 18 24

2006 2007

B

JuneJune DecDec

Perimeter based on length

3. Year-to-year trends

% PWP Monterey by cohorts

10%

30%

50%

70%

90%

20060-1 y

20071-2 y

20082-3 y

20070-1 y

20081-2 y

20080-1 y

20091-2 y

% P

WP

Per (area)

Per (len)

Wt (len)2005 spawn

2006 spawn2007 spawn

San Diego Bait Sardines

80

100

120

140

160

180

200

0 12 24 36 48 60 72

Month

SL

, mm

2006 2007 2008 2009 2010 2011

Nearshore sardines migrate away when they reach 170-180 mm SL

San Diego PWP’s appear to have shifted since 2008

San Diego Bait Sardines

0%

25%

50%

75%

100%

0 12 24 36 48 60 72

Month and Year

PW

P %

Per(area)Per(length)Wt(length)

2006 2007 2008 2009 2010 2011

Since July, 2008, San Diego sardine otoliths have had similar morphological characteristics as Gulf sardine

0%

20%

40%

60%

80%

Mon

'07

SD'07

SD'08a

SD'08b

SD'09

SD'10

SD'11

Ens'08

Gulf'06

Date and Region

PW

P, %

Per (A)Per (L)Wt (L)

Both San Diego and Monterey sardine otoliths have had “warmer” PWP features since 2008

% PWP, San Diego and Monterey (age 1-2)

0%

25%

50%

75%

SD '07

Mon

'07

SD '08a

SD '08b

Mon

'08

SD '09

Mon

'09

SD'10

Mon

'10

%P

WP

Per (area)Per (len)Wt (len)

Ensenada PWP's(n=number of otoliths)

0%

20%

40%

60%

1992 2000 2008

PW

P %

Per(area)

Per(length)Weight(length)

158

76

96

Ensenada sardine otoliths are light and not highly lobed

Spring surveys, 2004 and 2009, Perimeter-Weight Profiles

4. Offshore adults

2004 and 2009 Surveys, California

20%

40%

60%

80%13 16 12 1 5 15 11 Avg 7 46 16 43 32 29 12 Avg

Trawl

PW

P, %

Per(A)

Wt(L)2004 2009

Avg SL=245 mm Avg SL=211 mm

SL vs. Otolith Weight: Spring surveys and live bait (2006-2011)

R2 = 0.0009

R2 = 0.5838

y = 0.0129x - 0.8597

R2 = 0.9264

0.5

1.0

1.5

2.0

2.5

3.0

3.5

100 125 150 175 200 225 250 275

SL, mm

Wei

ght,

mg

2004

2009

Bait

The relationship between otolith weight and standard length was uncoupled in offshore California sardine in 2004

•Regional differences were found between Monterey, San Diego, and Baja California populations

•Age-0 otolith PWPs may resemble those of older sardine from the same locale and cohort

•Regional characteristics may change over time

•San Diego sardine since mid-2008 have had characteristics of southern Baja sardine. Why? Expansion of Baja populations, temperature preferences, oceanographic conditions?

Conclusions from otolith morphology studies

Where do we go from here?

1. TRINATIONAL RESEARCH EFFORT: Sharing otoliths, methods, and data

2. FISHERMEN: Noting juvenile schools, special collections of young sardine

3. PORT SAMPLERS: Special set-asides of juveniles

4. STOCK ASSESSMENT TEAM: Is there a possible role for otolith attributes in models and predictions?

Acknowledgments•Collaborators and co-authors at SWFSC

•Collectors at SWFSC, NWFSC, California Fish & Game, Fisheries & Oceans (Canada), CICESE & CICIMAR (Mexico)

•Everingham Bros. for monthly samples of live sardine

For further reading…