This document discusses various methods for marking and tagging fish, including biological, chemical, and physical methods. Biological methods include morphological marks like scale patterns and genetic marks. Chemical methods involve immersing, injecting, or feeding fish dyes or markers. Physical methods include external tags like strap tags and internal tags like coded wire tags implanted in tissue. The advantages and disadvantages of different tagging methods are considered for factors like retention rate, effects on fish, and costs.

1. Sayeed Bin Rahaman
M. Sc. Zoology (III Sem.) Fishery Science & Aquaculture

2. Marking- is a technique to show something (fish) to be different or special, .
Tagging- in which some device is attached , is probably the most common way of
marking fish for future identification. All fish tags have one thing in common, regardless
of the shape or kind of tag; each is stamped or printed with a serial number and the
name of the laboratory or agency that is conducting the tagging study.
Marking & tagging

3. Significance
• for better understanding of movement & migration pattern.
• to discriminate between the mixed stocks.
• to estimate natural mortality, fish growth, length-weight relationship, population size
• to estimate relative abundance.

4. Tag selection
Great consideration should be given to the choice of tag-type when developing a
tagging programme.
• objectives of the tagging study or programme
• durability, longevity and stability of the tag
• stress associated with the capture, handling and tagging process
• size and number of individuals to be tagged
• ease of tag application
• cost of purchasing the tags and conducting the tagging experiment

5. Biological- Morphological Marks; Genetic Marks
Chemical- Immersion; Injection; Feeding
Physical-
•External: Strap tag; Cart /anchor tag; Spaghatti tag; Petersen tag;
Atkins tag
•Internal: Internal Coded wire tag; Body cavity tag; Passive integrated transponder
tag; DST GPS Tag
Marking and Tagging Methods

6. Biological method
Morpholological marks
Natural marks include meristic counts, proportional sizes of body parts, shape and
coloration and circulus patterns of scales. The use of meristic and morphometric
marks is limited because these traits are subject to environmental and genetic
influences, which frequently overlap among populations.
Genetic marks
The use of genetic markers for identification purposes has been described by
Hansen et al. (1995). To withdraw genetic marks, only a sample of body tissue is
needed for analysis.

7. Chemical marks
Immersion-In this technique fish simply
immersed in chemical.
Injection-It is a self explainating techniqe.
•Possible problems are concentration of
substance, and location of injection.
Feeding-Works well in laboratory and hatchery settings where fish can be monitored
and feed the dyes. Without monitoring the fish problems can occur where some
individuals do not feed as much as others and the marker is not as clearly recognized.

8. Physical method
Tags – Internal and External

9. Strap Tags
This tag is a flat metal strip .The tag was adapted from a cattle ear tag and was first
used on salmon in Alaska. The tag may be attached to the gill cover, to the lower
jaw , or to the top of the tail fin and has been used on halibut, cod, haddock, tuna,
and in fresh-water fishes.

10. Dart/Anchor/Streamer Tags
Dart tags - made of nylon shaft with a barbed end and a vinyl tube that fist over
the upper end of the shaft. The barbed end of the shaft holds the tag in the fish
and the tube contains the tag information
Anchor tag (Floy tags)- applicable for long-term studies on migration on adult
migratory species. This tag is a modified dart tag in which a nylon T-bar replaces the
harpoon like head of the dart tag.

11. A loop of vinyl tubing that passes through the fish. Information is printed directly on
the tubing. Two variation of the tag are lock-on and cinch-up tags, which use special
locking devices instead of a knot. The tag is retained well and inexpensive, but
application is time-consuming
Spaghetti tag

12. Petersen Tag
Petersen Disc tag below the dorsal fin
of a warmouth.
Named for the Danish biologist who invented
it in 1894 . The tag consists of two Celluloid
or plastic discs, about one-half inch in
diameter, attached with a pin or wire to some
part of the fish . The tag can be attached to
the gill covers through the back muscles , or
through the fleshy part of the tail.

13. This tag is extremely simple, consisting of a disc or flat plate attached by a thread or
wire that pierces the tissues. It was first used in l873 by Charles G. Atkins who tagged
Atlantic salmon .There have been many variations in this tag, particularly in the size
and shape of the plate and the materials used. The most recent variation is the use of
vinyl plastic for the plate and vinyl plastic tubing for the wire .
Atkins tag

14. Mutilation
Clipping or punching fins or other body parts which can later be used to identify
individuals. The pectoral or pelvic fin was clipped at the base, while the upper
or lower caudal fin lobe was removed .Usually two fins are clipped.

15. Physical Methods (External)
Advantages
• Easy and fast to apply, requiring only simple technology for the application.
• Applicable to large numbers of fish and to a great range of species.
• Easily detected due to the exterior attachment.
• Provide space for printing information.
• Because of low cost, can provide a large number of returns, and sufficient data .
•Long tag-retention time (depending on the type of tag).

16. Disadvantages
• Does not provide information until recapture.
• Return rates may be variable.
• May affect growth, health and survival, behaviour and swimming/hiding.
• May become entangled in aquatic vegetation or in fishing gear.
• Can be difficult to apply or may not be applicable to very small fish.

17. Subcutaneous tags (detected externally )
Inexpensive plastic discs imprinted with serial numbers , are planted in between
the outer layer of skin and muscles by a small incision.
Visible Implant
Elastomer

18. Coded Wire Tag
A small piece of wire injected into a fish
using small applicators or by hand.
These tags can be placed in the snout,
necks, caudal fins, and any other
muscular area. The tags can be
detected with a sensitive metal detector
or an x-ray.

19. Body Cavity Tags
• A device is inserted completely into the body
cavity through a small incision. All information
is printed on the tag, which is typically made of
plastic.

20. Small glass-encapsulated electromagnetic coil and microchip that is inserted into the
body cavity by using a veterinary syringe. The tags are energised at frequencies of
approximately 400 kHz generating a return signal of between 40 to 50 kHz. Tags can
be decoded with a portable hand-held reader.
Passive Integrated Transponding (PIT) tags

21. DST GPS TAG
Data Storage tag (DST) Global Positioning System (GPS) can be attached externally
or implanted into fish. DST GPS can receive information about geographic position
from satellites.

22. Physical Methods(Internal)
Advantages
 Do not protrude from the body.
 Do not require removal of parts of the fish.
 Non-toxic and may put less stress on the fish compared to other
tagging methods.
Disadvantages
 Can be expensive.
 Trained personnel are necessary.
 Recovery is difficult.