World Aquaculture Magazine -December 2021

WWW.WA S .ORG • WORLD AQUACULTURE • DECEMBER 2021 59 species, size of the animal and size of the tag. For a tagging procedure to be effective, there must be a high level of tag retention and a negligible effect of tagging on individual performance, behavior and survival (Lauzon-Guay and Scheibling 2008). The US Department of Agriculture (USDA) and US Food and Drug Administration (FDA) have approved the use of PIT tags with the condition that the part of the animal carrying the implanted device will not be used for human consumption. Thus, body cavity location is recommended for all fish that will be released where fish may be captured and consumed. In selective breeding programs, physical and genetic tagging methods are crucial as different families must be reared separately until reaching a taggable size, injected with tags and later reared in common test environments (WorldFish Center 2004). Tagging methods are important for identifying individuals, families and year class identification and to construct a pedigree record to aid in genetic evaluation and selection (Ninh 2009). With an attempt to selectively target growth trait in rohu Labeo rohita , the Indian Council of Agricultural Research-Central Institute of Freshwater Aquaculture (ICAR-CIFA) initiated the selective breeding program in 1992. Six different stocks of rohu (Ganga, Yamuna, Brahmaputra, Sutlej, Gomati and ICAR-CIFA farm stock) were included in the breeding program. Different, locally available tags were used to identify and maintain different stocks but none were suitable or effective for long-term retention. Very often, secondary infection appeared following application of external tags. Considering all the drawbacks, an internal tagging systemwith PIT tags was I nternal tagging of fish with a Passive Integrated Transponder (PIT) has emerged as a technique since the mid- 1980s for gathering information about fish ecology and fish movements (Larsen et al . 2013). The study, identification and tracking of animal, bird and invertebrate movements have been facilitated by the use of internal PIT tags (Gibbons and Andrews 2004). PIT tags are electronic glass-encased microchips that are dormant until activated and work on specific radio frequencies for positive identification. They are activated by the generation of a close-range electromagnetic field emitted by a scanning device/reader as there is no requirement for any internal power source throughout their lifespan (Kurth et al . 2007). These low-frequency tags can be read through soil, wood and water and can be detected in milliseconds. The longevity of PIT tags is indefinite because the tag has no battery, but this restricts tracing to a limited range. Read range refers to the distance fromwhich a PIT tag can be appropriately read, varying from a few inches to about one foot. The advantage of using these tags lies in the fact they can be read at a close but practical range. Antenna power, operation frequency, tag orientation and interference from other devices are the factors that contribute to the specific read range of PIT tags. This technique thus offers quick data collection, error minimization in data recording and long-term reliability. The tags are inconvenient for use in noisy environments and with ferrous metals because they cause interference of electromagnetic communication between the PIT tag and reader. PIT tags have been mostly inserted into the muscle or abdominal cavity and the implant site of the tag depends on the Importance of PIT Tagging in Aquaculture Selective Breeding Programs Avinas Rasal, Madhulita Patnaik, Khuntia Murmu, Jitendura Kumar Sundaray and Kanta Das Mahapatra FIGURE 1. PIT tags. The study, identification and tracking of animal, bird and invertebrate movements have been facilitated by the use of internal PIT tags. PIT tags are electronic glass-encased microchips that are dormant until activated and work on specific radio frequencies for positive identification. They are activated by the generation of a close-range electromagnetic field emitted by a scanning device/reader as there is no requirement for any internal power source throughout their lifespan. ( C O N T I N U E D O N P A G E 6 0 )