Fish Marking

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Fish Marking

• Not in your textbook!

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Reasons for marking fishes

• To identify stocks
• To assess stock size
• To assess growth and mortality rates
• Mark must have minimum interference with biology
  of fish while having maximum utility

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Requirements of the mark

• 1) persist for life of fish
• 2) not interfere with behavior
• 3) not make fish more vulnerable to predators
• 4) not tangle with weeds or nets
• 5) easy to apply (minimize equipment, stress to
  fish)
• 6) applicable to broad range of sizes

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More requirements

• 7) variable to allow distinctive marking of
  groups
• 8) not create health hazard
• 9) easily detected in field by untrained people
• 10) inexpensive, easy to obtain
• 11) minimum confusion in reporting
• 12) remain unaffected by preservatives
• 13) no effect on growth or survival of fish

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Selection considerations

• 1) length of time
• 2) skill of personnel
• uniform application, minimum disturbance
• 3) species to be tagged
• 4) means of recovery
• commercial or sport fishery (incentive)
• 5) concurrent marking programs

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Types of marks

• 1) tags
• 2) fin clipping
• 3) branding
• 4) dye
• 5) tattooing
• 6) subcutaneous injection
• 7) genetic

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Population DynamicsChapter 6
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Fish Population Assessments

• Direct counts
• 1) construct weir/trap system in river
• 2) use counting platform
• 3) use electrical counting system, hydroacoustics

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Fish Population Assessments

• Direct counts
• 1) construct weir/trap system in river

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Fish Population Assessments

• Direct counts
• 1) construct weir/trap system in river
• 2) use counting platform

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Fish Population Assessments

• Direct counts
• 1) construct weir/trap system in river
• 2) use counting platform

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Fish Population Assessments

• Direct counts
• 1) construct weir/trap system in river
• 2) use counting platform

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Fish Population Assessments

• Direct counts
• 1) construct weir/trap system in river
• 2) use counting platform

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Fish Population Assessments

• Direct counts
• 1) construct weir/trap system in river
• 2) use counting platform
• 3) use electrical counting system, hydroacoustics

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Fish Population Assessments

• Direct counts
• 1) construct weir/trap system in river
• 2) use counting platform
• 3) use electrical counting system, hydroacoustics

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Fish Population Assessments

• Indirect counts - population estimates
• 1) plot method
• 2) mark recapture - Peterson method
• 3) mark recapture - Schnabel method
• 4) change in ratio or dichotomy method
• 5) removal sampling - Zippin method