A10. Coded wire and Visible Implant Tags

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Figure 1: Visible Implant Elastometer (VIE) tag. Source : https://www.nmt.us/visible-implant-elastomer/

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1. Objectives[edit]

Coded wire and Visible Implanted tags (VI tag) are mainly used to:

  • Tag large quantities of fish in mark-recapture experiments.
  • Tag fish for citizen science programs. For instance, assessing the impact of recreational fisheries; fish are caught by anglers, who record the capture location and metrics (fish length, weight etc.).
  • Evaluate stocking operations.
Figure 2: Visible Implant Alpha Tag. Source : https://www.nmt.us/vi-alpha/

2. Method summary[edit]

Visible tags are available in a variety of shapes, all allow for identification of marked fish, individually or not. Tags are usually implanted with an injector. Many studies are available on tag retention and fragmentation. There are several types of tags commonly used:

  • Visible Implant Elastometer (VIE) Tag: a non-immunogenic polymer that is injected into the fish in liquid form and subsequently cures into a pliable solid. It is implanted beneath clear or translucent tissue and remains externally visible (Figure 1). Several colours are available including the option for fluorescent tags.
  • Visible Implant Alpha Tag: small fluorescent tag with alphanumeric code to identify each fish individually. A UV lamp is used to detect fluorescence, making the tag visible (Figure 2).
  • Coded Wire Tag (CWT): consists of a (sub)-millimetre wire spool. This is loaded into an injector that marks the tag with rows of numbers denoting the specific batch or individual number before injecting. The tag can be electronically detected and must be removed from the fish in order to be read using a microscope (http://fish-notes.blogspot.com).
  • Plastic Tags of Different Shapes: directly inserted in the fin skin at different locations, depending on the morphology of the fish and it’s behaviour. Several different variations are available: Self Locking, T-Bar Anchor, Body Cavity, Stainless Steel Dart, Polyethylene Streamer, Plastic Tipped Dart, Spaghetti Tags and Petersen Discs (Figure. 4).
  • Less commonly used tags include X-ray Micro-Tags, Jaw Tags, and Paper Fasteners.
Figure 3: Coded Wire Tag (CWT). Source : https://www.nmt.us/cwt/

The operator should select the best type of tag to use, according to the species studied.

3. Advantages[edit]

*Advantages and disadvantages are specific according to the type of tag. Consult operator manuals*

  • Very cheap and fast.
  • Allows for tagging of large numbers of fish.
  • Suitable for small species and young stages of growth for larger species. Note: this is not the case for all tag types.
  • Long term visibility and high detection rate. Note: visibility varies between tag types, depending on colour and shape.
  • Some tags can be used in saltwater.
  • Allows for biometry.

4. Disadvantages[edit]

*Advantages and disadvantages are specific according to the type of tag. Consult operator manuals*

  • Fish has to be directly captured for identification.
  • Can impact fish survival, e.g. increased visibility can increase chance of predation.
  • Requires level of expertise to ensure tags are implanted properly.
Figure 4: Some tag exemple (dart tag, anchor tag). Source : https://hallprint.com/fish-tags-summary.

5. Recommendation for method application[edit]

*Recommendations can differ according to the type of tag. Consult operator manuals.*

  • Statistically estimate the number of fish needed for the study.
  • Chose the least intrusive tag according to: the objectives and fish morphology, species behaviour, previous studies on tag retention, visibility and mortality risk.
  • Consider adding e-mail or contact information to each tag for reporting.

6. Cost[edit]

  • Tag: usually a few pence per tag.
  • Tag injector: £100 – £200.
  • Labour: dependent on survey and number of fish tagged.

7. Data analysis[edit]

Mark-recapture analysis with detection probabilities, estimation of fish population size.

8. References[edit]

  1. Blankenship, H. L., & Tipping, J. M. (1993). Evaluation of visible implant and sequentially coded wire tags in sea-run cutthroat trout. North American Journal of Fisheries Management, 13(2), 391-394.
  2. Mourning, T. E., et al. (1994). Comparison of visible implant tags and Floy anchor tags on hatchery rainbow trout. North American Journal of Fisheries Management, 14(3), 636-642.
  3. Kincaid, H. L., & Calkins, G. T. (1992). Retention of visible implant tags in lake trout and Atlantic salmon. The Progressive Fish‐Culturist, 54(3), 163-170.
  4. Niva, T. (1995). Retention of visible implant tags by juvenile brown trout. Journal of Fish Biology, 46(6), 997-1002.
  5. http://fish-notes.blogspot.com/2011/09/marking-and-coded-wire-tagging-at.html
  6. http://www.floytag.com/uploads/floycatalog.pdf