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…