1 / 22

Fish Marking

Fish Marking. Not in your textbook!. 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. Requirements of the mark. 1) persist for life of fish

bullardr
Télécharger la présentation

Fish Marking

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fish Marking Not in your textbook!

  2. 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

  3. 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

  4. 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

  5. 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

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

  7. Determining the Age of Fish

  8. Useful fish structures In temperate regions, fish growth is seasonal. Changes in growth rate are recorded in the growth of hard structures in fishes. These structures can be used to determine fish age.

  9. Scales

  10. Otoliths

  11. Fin rays/spines

  12. Cleithra

  13. Vertebrae

  14. Various useful structures

  15. Various useful structures

  16. Back calculation Growth of fish scale is proportional to growth of fish length Length at each age can be determined from scale, if fish length is known

More Related