Fish Habitat and Otolith Chemistry

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Fish Habitat and Otolith Chemistry

• By
• Nate Bickford
• and Brenda Norcross

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Otolith Introduction

• The location and identification of essential fish
  habitat has become a major focus of fisheries
  management.
• Traditional assessments of habitat use have
  relied on mark and recapture techniques.
• Recently fisheries managers have used otolith
  chemistry to identify fish movement and habitat.

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Fish in Chukchi

• Fish were collected during the Russian American
  Long Term Census of the Arctic (RUSALCA) Cruise
• Bering Flounder (Hippoglossoides robustus)
• BF is one of the most abundant flatfish in the
  Chukchi Sea.

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Methods

• Fish were collected from 7 sites in the Chukchi
  Sea.
• Otolith were removed and thin sectioned in a
  clean environment.
• Chemical analyses were done by Laser Ablation
  Inductively Coupled Plasma Mass Spectrometry
  (LA-ICP-MS otoliths LSX-500).
• We are looking for elemental differences between
  core (natal) and edge (where they were
  collected).
• Elemental ratio we are concerned with are Sr/Ca
  Sr87/Sr86, Ba/Ca, and Mg/Ca.

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Bering Flounder were collected at sites
13, 15, 18, 20, 23, 25, and 58
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• Using a Quadratic Discriminant Analysis (QDA)
  different sites were grouped as water masses
• Then I used the QDA to predict the membership in
  each water mass

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• There are multiple stocks of Bering flounder in
  the Chukchi Sea.
• Water mass 2 is essential for Bering Flounder in
  the Chukchi Sea
• Why is the habitat in water mass 2 better

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Preliminary data

• Gymnocanthus tricuspis, Arctic staghorn sculpin
• Also collected during the RUSULCA cruise

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Arctic Staghorn Sculpin were collected at sites
6, 11,13, 15, 17,18,20, 23, 25, 27, 58
62, 73, 85, 106, and 107
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Artic staghorn

• Possible multiple groupings in three to four
  water masses
• Next Step discriminant statistics

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Acknowledgments

• Funding
• National Science Foundation

• Sonja Bickford
• Robyn Hannigan
• Brenda Norcross
• Chris Stark
• Brenda Holliday
• Matt Keyse
• Fisheries Otolith Group (FOG)
• Tom Weingartner
• Seth Danielson