Estimating daily age of catfish using otoliths

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Estimating daily age of catfish using otoliths
Peter C. Sakaris and Elise R. Irwin Alabama
Cooperative Fish and Wildlife Research
Unit Auburn University
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Objective

• Assess the effects of hydrology on spawning,
  hatching success and growth of YOY catfishes in
  regulated systems
• - Daily Aging

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(No Transcript)
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Prepositioned Area Electrofishers

• Juveniles catfishes were collected at day and
  night using PAEs on sand and gravel bars at two
  mainstem sites and three tributary sites.

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Prepositioned Area Electrofishers
YOY Channel Catfish lt 100 mm
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YOY Catfish Daily Aging Otolith Removal
Use same methods described for adult catfish,
with a few exceptions 1) Use a dissecting scope
or a portable lamp with magnification, 2) use a
scalpel to cut into the fish, and 3) do not drop
the otoliths (a little larger than a grain of
salt).
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YOY Catfish Daily Aging Otolith Processing

• Mount otoliths in CrystalBond mounting wax using
  a dissecting scope and small dissecting forceps
  (initially, same as adult otoliths, but on a much
  smaller scale)
• Slowly grind to core using 600 grit, fine
  sandpaper
• Routinely check otolith using a compound
  microscope to see if core is visible
• When core is visible, flip otolith over and
  slowly grind other side down until you have a
  thin section
• Routinely check otolith to see if daily rings are
  visible

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Catfish have daily rings.
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Future Work

• Refine aging techniques -
• - Use finer grit when grinding other side of
  otolith
• Fewer scratches, more polished
• Use alternative mounting material
• Validate the technique using known-age fish
• Apply it to wild fish

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Dont forget the little guys, ANY QUESTIONS?