Marking and tagging for releasing activity

Masatoshi FUTAGAWA
August 27, 2017

Markers and tags
The marking or tagging is essential activity in order to identify the released fish in the field. According to identification, we evaluate the activity such as growth, survival, migration of the fish at field and evaluate economic effect. Thus, it is necessary to announce to public that request to inform catch data about tag code, location and size of fish.

·         Nasal septum defect: Some hatchery made fish shows nasal septum defect, nose holes are connected. The data have to revising by the defect rate of the released fish batch.


·         Plucking fins / spines: Pluck ventral, pectoral fin or spine at dorsal fin. The method does not harm any survival and growth according to the paper. Even so, the mark recover within few years.



·         Anchor / darts tag: The tag has some number and letters, used commonly for fish. The tag removes sometime.
 

·         Alizarin complexone (ALC) / tetracycline (TC) staining:  Otoliths scale and bones are stained by ALC or TC, larvae and juvenile immerse in the solutions or feed solution mixed in diet. Advantages of the method are applicable for small samples with large number at once. It not harms growth and survival and keeps years. Disadvantage is not able to identify from outward appearance. Hence, the marker combines with physical markers such as plucking.
        

·         Visible implanting elastomer (VIE): The material made of fluorescent silicon and it is injected at transparent or white tissue of fish. The marker identifies easily but removes sometime.



·         Coded wire tag (CWT): The tag made of stainless steel wire 0.25 mm with numbers which read by magnifier.  The tag is implanted by injector at length of 0.5, 1.1, 1.6 and 2.2 mm.


·      Passive integrated transponder (PIT) tag: The tag function by radio identification, 70 years lifetime. However, the tag cost is around 60 USD in each tag. It use for salmon migration in a stream or identification individual broodstock. Recently the tag applies to pet, dogs and cats.

·         Acoustic transponder (Pinger); The transponder used for tracking fish and water temperature and depth simultaneously. It function long distance and long term (1 year). The transponder is inserted in abdomen surgically in 23 cm is the minimum fish size, accepting 2 % of body weight based on uses.

   

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