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Marine migrations of Steelhead, Coastal Cutthroat, and Steelhead x Cutthroat hybrid smolts

Marine migrations of Steelhead, Coastal Cutthroat, and Steelhead x Cutthroat hybrid smolts. Megan Moore, NOAA Fred Goetz, University of Washington Barry Berejikian , NOAA Skip Tezak , NOAA Don Van Doornik , NOAA Jose Reyes Tomassini , NOAA. Extent of Hybridizaton.

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Marine migrations of Steelhead, Coastal Cutthroat, and Steelhead x Cutthroat hybrid smolts

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  1. Marine migrations of Steelhead, Coastal Cutthroat, and Steelhead x Cutthroat hybrid smolts Megan Moore, NOAA Fred Goetz, University of Washington Barry Berejikian, NOAA Skip Tezak, NOAA Don Van Doornik, NOAA Jose Reyes Tomassini, NOAA

  2. Extent of Hybridizaton • Hybridization has been documented in • several streams from Alaska to California • (first formally documented by Utter 1981*) • Hybrid swarms are generally not formed • in anadromous populations • Rate of hybridization is generally < %30 • Frequency of occurrence: • - Campton and Utter (1985) – 2/23 • Puget Sound streams • - Bettles et al. (2005) - 13/37 • Vancouver Island streams • - D. Van Doornik , (2006- 2009) – 8/8 Hood Canal streams (some very low levels) *CJFAS 38:1626-1635

  3. Life History Similarities Anadromous or freshwater-residents Iteroparous 1-4 year freshwater residency Life History Differences

  4. The Study • Study conducted over three years (2006, 2007, 2008) • in Big Beef Creek • Steelhead and cutthroat smolts tagged with acoustic • transmitters 115 phenotypic steelhead 68 phenotypic cutthroat • Four diagnostic microsatellite loci were genotyped to determine hybridization • - both SH and CT alleles at all four loci = F1 • - mix of hetero- and homozygous genotypes = F1+ • more SH alleles = SH F1+ • more CT alleles = CT F1+

  5. The Analysis • “Track” Parameters • Estuarine residence time • = last estuary detection – first estuary detection • Total track distance • = sum of all track segments • Tortuosity • = total track distance/range of track • Hood Canal residence time • = last Hood Canal detection – last estuary detection AquaTrack, developed @ Manchester by Jose Reyes - Tomassini

  6. Patterns of Hybridization *One hybrid of undetermined type • Consistent frequency of hybridization between phenotypes • Also consistent with results from sampling in 1996 (Young et al. 2001)  22.2% • Phenotypic steelhead hybrids tended to be F1’s while more phenotypic cutthroat hybrids were F1+ • Generally, the observed F1:F1+ ratio (1:1.3) deviates from expected (1:6)

  7. Results MANOVA: Species ~ estuary time + residence time + tortuosity  (F2,148 = 0.414, P = 0.000)

  8. Cutthroat Detection Density Cutthroat

  9. Steelhead

  10. Hybrids

  11. Detection Densities Cutthroat Steelhead Hybrids 2008 data

  12. Migration Patterns (km)

  13. Migration Patterns (km)

  14. Migration Patterns (km)

  15. Migration Patterns (km)

  16. Conclusions • Rates of hybridization are consistent (as opposed to episodic) and low in • Big Beef Creek • Phenotypic steelhead hybrids tend to be F1’s, while phenotypic cutthroat hybrids are more likely F1+ • Overall, there are fewer backcrosses than expected, suggesting lower • hybrid fitness • Hybrids display different migration behaviors than do pure steelhead or • cutthroat • Most hybrid migration parameters are intermediate to pure species • Hybrids do not necessarily “act” like the species they resemble

  17. Conservation Concern, Evolution, or Adaptive Response? Conservation Concern: Species collapse Extinction of native genotypes • Anthropogenic Causes: • Habitat loss/destruction • Evolution: • Increased genetic diversity • Novel genetic combinations Increased evolutionary potential: Ability to respond to environmental change and/or variable environment Increase reproductive success: Fewer mates = less competition Females less choosy, sneaking more successful Better to mate interspecifically than not at all • Adaptive Response: • Low population sizes

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