Stock Structure of Pacific Sardine (Sardinops sagax), an ongoing question

John R. HydeSouthwest Fisheries Science Center, La Jolla

Tools at our disposal• Catch and ichthyoplankton data• Morphometry

– whole fish– meristics– otolith

• Artificial tagging– large scale studies in the 1930’s & 40’s

• Natural tagging – parasites– chemical/isotopic signatures in otoliths

• Genetic analyses– blood type– allozymes– mtDNA sequencing– microsatellites

Tools at our disposal• Catch and ichthyoplankton data• Morphometry

– whole fish– meristics– otolith

• Artificial tagging– large scale studies in the 1930’s & 40’s

• Natural tagging – parasites– chemical/isotopic signatures in otoliths

• Genetic analyses– blood type– allozymes– mtDNA sequencing– microsatellites

Temporal shifts in spawning areas

Smith 2005

Variable Catch with SST

Felix-Uraga et al. 2005

The 3 Stock Hypothesis

Felix-Uraga et al. 2005

Felix-Uraga et al. 2005

Tools at our disposal• Catch and ichthyoplankton data• Morphometry

– whole fish– meristics– otolith

• Artificial tagging– large scale studies in the 1930’s & 40’s

• Natural tagging – parasites– chemical/isotopic signatures in otoliths

• Genetic analyses– blood type– allozymes– mtDNA sequencing– microsatellites

Garcia-Rodriguez et al. 2011

Body Morphology

Hedgecock et al. 1989

“cold”

“temperate”

“warm”

“cold”

“warm”

Variations in Vertebral Counts

Felix-Uraga et al. 2005

Variability in Otolith shape

Otolith morphometry (the frill factor)

Otolith measurements greater than predicted (50% = average of all otoliths). Number of otoliths for each region indicated on the graph (total = 4147 otoliths).

Javor et al 2011

Otolith morphometry (the frill factor)

Otolith measurements greater than predicted (50% = average of all otoliths). Number of otoliths for each region indicated on the graph (total = 4147 otoliths).

Average

Frilly and light

Javor et al 2011

Tools at our disposal• Catch and ichthyoplankton data• Morphometry

– whole fish– meristics– otolith

• Artificial tagging– large scale studies in the 1930’s & 40’s

• Natural tagging – parasites– chemical/isotopic signatures in otoliths

• Genetic analyses– blood type– allozymes– mtDNA sequencing– microsatellites

Tagging Studies

• Large numbers of fish tagged along Pacific Coast and recovered in canneries

• Movement of fish between Canada and San Diego

• Northern Baja fish showed limited northward movement

• No tag returns from Southern Baja

Tools at our disposal• Catch and ichthyoplankton data• Morphometry

– whole fish– meristics– otolith

• Artificial tagging– large scale studies in the 1930’s & 40’s

• Natural tagging – parasites– chemical/isotopic signatures in otoliths

• Genetic analyses– blood type– allozymes– mtDNA sequencing– microsatellites

Baldwin et al. 2011

Parasites as natural tags

• trematode Lecithaster gibbosus suggests retention of locally spawned fish in the Pacific NW• trematode Myosaccium ecaude supports coastwide migration

Oxygen Isotope studies

Valle & Herzka 2008

Isotope values used to extrapolate average temperature conditions experienced by sardine (circles). Dashes denote monthly average SST at location.

Oxygen Isotope studies

Valle & Herzka 2008

Isotope values used to extrapolate average temperature conditions experienced by sardine (circles). Dashes denote monthly average SST at location.

Tools at our disposal• Catch and ichthyoplankton data• Morphometry

– whole fish– meristics– otolith

• Artificial tagging– large scale studies in the 1930’s & 40’s

• Natural tagging – parasites– chemical/isotopic signatures in otoliths

• Genetic analyses– blood type– allozymes– mtDNA sequencing– microsatellites

Challenges for Population Genetics

• Known migratory behavior– Geographic overlap but temporal separation?

• Repeated large-scale population fluctuations– Multiple population bottlenecks?

• Human mediated gene flow– Transport and release of sardine by sportfishing vessels

How to address these challenges?

• Large sample size and/or large number of genetic markers• Discrete temporal sampling to address hypothesized movements of stocks• Range-wide sampling

Variations in Blood Type

Smith 2005

Variations in Blood Type

Smith 2005

Genetic Studies and the Goldilocks Problem•Allozymes – not enough variation

•Hedgecock et al. 1989 – 32 allozyme loci•“There is so little variation within and between Pacific sardine populations that it is not possible to test whether distributions of genotypes conform to the expectations of random mating or whether allelic frequencies are heterogeneous throughout the range of populations sampled. That sardines in widely separated localities have the same rare alleles suggests strongly, however, that there has been substantial gene flow among contemporary populations.”

•Mitochondrial DNA sequences - too much variation

•Microsatellites – way too much variation•17 microsatellite loci (Pereyra et al. 2004, Hyde unpublished)

•21-72 alleles per locus (mean = 44.1)

Garcia-Rodriguez et al. 2011

Collection info and hypothesized stock

membership

Felix-Uraga et al. 2005

Pairwise Population comparisons

Canada OregonN.

Calif.San Fran.

S. Ca (April)

Ens. (June)

Ens. (Dec)

S. Ca (Nov)

Cedros Is.

MB (May)

MB (Nov) GOC

Canada * 0.5384 0.1210 0.0578 0.4328 0.1351 0.5153 0.0926 0.0995 0.3434 0.1044 0.2443

Oregon -0.0006 * 0.4816 0.0003 0.2443 0.2293 0.4812 0.0918 0.0461 0.6613 0.8025 0.3274

N. Calif. 0.0000 -0.0017 * 0.0060 0.3275 0.0209 0.2358 0.0577 0.0004 0.1712 0.1367 0.0013

San Francisco 0.0012 0.0026 0.0230 * 0.1365 0.0418 0.0596 0.0043 0.0254 0.0174 0.1439 0.0199

S. Calif (April) -0.0006 -0.0006 -0.0004 0.0011 * 0.3737 0.4959 0.0598 0.1932 0.4598 0.1346 0.3798

Ensenada (June) 0.0010 0.0004 0.0016 0.0013 0.0001 * 0.2285 0.0031 0.1558 0.8253 0.2160 0.0023

Ensenada (Dec) -0.0002 -0.0005 0.0003 -0.0001 -0.0007 0.0002 * 0.7735 0.0466 0.2618 0.2808 0.4129

S. Calif (Nov) 0.0009 0.0011 0.0008 0.0025 0.0009 0.0015 -0.0009 * 0.1269 0.3421 0.0903 0.0690

Cedros Island 0.0004 0.0001 0.0005 0.0009 -0.0001 0.0010 0.0009 -0.0001 * 0.0372 0.0102 0.0167Magdalena Bay

(May) -0.0003 -0.0015 -0.0007 0.0012 -0.0003 -0.0018 -0.0007 -0.0012 0.0015 * 0.0962 0.1873Magdalena Bay

(Nov) 0.0008 -0.0014 -0.0006 0.0002 -0.0002 0.0003 0.0000 -0.0004 0.0006 0.0015 * 0.1663

Gulf of California -0.0007 -0.0006 0.0006 0.0023 -0.0004 0.0011 -0.0003 -0.0001 0.0002 -0.0002 0.0000 *

Pairwise FST values below diagonal, p-values above diagonal. Significant values in bold

Cold Stock Temperate Stock

Warm Stock????

AMOVA Adjacent Sample Pooling Analyses

4 GroupsFST = 0.00093, p = 0.07FSC = 0.00059, p = 0.36FCT = 0.00035, p = 0.03

Conclusions and Future Directions

•Tagging data supports coastwide migratory behavior•Evidence exists for geographically associated phenotypic heterogeneity•Likely driven by environmental conditions

•Low to no genetic heterogeneity•The need for markers under natural selection

•Heterogeneity in otolith oxygen isotopes•Driven by environmental conditions

•A need for a comprehensive rangewide survey