Download presentation
Presentation is loading. Please wait.
1
Stock Structure of Pacific Sardine (Sardinops sagax), an ongoing question John R. Hyde Southwest Fisheries Science Center, La Jolla
2
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
3
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
4
Temporal shifts in spawning areas Smith 2005
5
Variable Catch with SST Felix-Uraga et al. 2005
6
The 3 Stock Hypothesis Felix-Uraga et al. 2005
7
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
8
Garcia-Rodriguez et al. 2011 Body Morphology Hedgecock et al. 1989 “cold” “temperate” “warm” “cold” “warm”
9
Variations in Vertebral Counts
10
Felix-Uraga et al. 2005 Variability in Otolith shape
11
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
12
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
13
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
14
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
15
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
16
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
17
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.
18
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.
19
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
20
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
21
Variations in Blood Type Smith 2005
22
Variations in Blood Type Smith 2005
23
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
24
Collection info and hypothesized stock membership Felix-Uraga et al. 2005
25
Pairwise Population comparisons CanadaOregon N. Calif. San Fran. S. Ca (April) Ens. (June) Ens. (Dec) S. Ca (Nov) Cedros Is. MB (May) MB (Nov)GOC Canada *0.53840.12100.05780.43280.13510.51530.09260.09950.34340.10440.2443 Oregon -0.0006*0.48160.00030.24430.22930.48120.09180.04610.66130.80250.3274 N. Calif. 0.0000-0.0017*0.00600.32750.02090.23580.05770.00040.17120.13670.0013 San Francisco 0.00120.00260.0230*0.13650.04180.05960.00430.02540.01740.14390.0199 S. Calif (April) -0.0006 -0.00040.0011*0.37370.49590.05980.19320.45980.13460.3798 Ensenada (June) 0.00100.00040.00160.00130.0001*0.22850.00310.15580.82530.21600.0023 Ensenada (Dec) -0.0002-0.00050.0003-0.0001-0.00070.0002*0.77350.04660.26180.28080.4129 S. Calif (Nov) 0.00090.00110.00080.00250.00090.0015-0.0009*0.12690.34210.09030.0690 Cedros Island 0.00040.00010.00050.0009-0.00010.00100.0009-0.0001*0.03720.01020.0167 Magdalena Bay (May) -0.0003-0.0015-0.00070.0012-0.0003-0.0018-0.0007-0.00120.0015*0.09620.1873 Magdalena Bay (Nov) 0.0008-0.0014-0.00060.0002-0.00020.00030.0000-0.00040.00060.0015*0.1663 Gulf of California -0.0007-0.00060.00060.0023-0.00040.0011-0.0003-0.00010.0002-0.00020.0000* Pairwise F ST values below diagonal, p-values above diagonal. Significant values in bold
26
Cold Stock Temperate Stock Warm Stock ???? AMOVA Adjacent Sample Pooling Analyses 4 Groups F ST = 0.00093, p = 0.07 F SC = 0.00059, p = 0.36 F CT = 0.00035, p = 0.03
27
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
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.