World Aquaculture Magazine -December 2021

62 DECEMBER 2021 • WORLD AQUACULTURE • WWW.WA S .ORG identification of the individual. This information was needed for estimation of heritability of the trait, breeding value of the individual and genetic correlations among traits. PIT tags were useful for keeping the pedigree record of selected fish by generation in the breeding nucleus. While preparing the mate allocation plan, PIT tags help to identify individuals and avoid mating between the same full- sib and half-sib families, thereby keeping a check on inbreeding. Conclusion PIT tags are popular because of their longevity, ability to allow identification of individual fish, ease of application and minimal effects on survival and growth (Zydlewski et al . 2006). The PIT tag is an effective, safe and secure device for marking carps owing to its small size and inert nature. A greater survival rate of the tagged fish could be achieved under field conditions through effective management practices, so that recovery of the PIT tag would be greater. Although costly, PIT tags can be reused after the animal is harvested for mass tagging in fish. The problem of inbreeding depression in many carp hatcheries can be addressed through the use of PIT tags for keeping pedigree information of broodstock, thereby avoiding inbreeding depression. The major role of tagging fish in selective breeding programs is to identify different broodstocks collected from different sources (riverine, reservoirs) or from different hatcheries and to maintain a pedigree record so as to avoid inbreeding in hatcheries by sidestepping matings of relatives. Use of PIT tags is, therefore, a useful tool in selective breeding and stock assessment programs as it could boost production of quality seed, thus contributing to sustainable aquaculture and enhanced productivity. Acknowledgements The authors are thankful to the Head of Fish Genetics and Biotechnology Division and the Director of ICAR-CIFA for their support and guidance. Notes K.D. Mahapatra, Fish Genetics and Biotechnology Division, ICAR- Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar- 751002, Odisha * Corresponding author: kdmahapatra@yahoo.co.in References Baras, E., C. Malbrouck, M. Houbart, P. Kestemont and C. Mélard. 2000. The effect of PIT tags on growth and physiology of age- 0 cultured Eurasian perch Perca fluviatilis of variable size. Aquaculture 185(1):159-173. Bateman, D.S., R.E. Gresswell and A.M. Berger. 2009. Passive integrated transponder tag retention rates in headwater populations of coastal cutthroat trout. North American Journal of Fisheries Management 29:653-657. Dieterman, D.J. and R.J.H. Hoxmeier. 2009. Instream evaluation of passive integrated transponder retention in brook trout and brown trout: effects of season, anatomical placement, and fish length. North American Journal of Fisheries Management 29(1):109-15. Foldvik, A. and E. Kvingedal. 2018. Long-term PIT tag retention rates in Atlantic salmon ( Salmo salar ). Animal Biotelemetry 6:3. doi.org/10.1186/s40317-018-0147-1. on two-month retention of PIT tags. A lower percentage of brown trout retained their tags in spring (56 percent) than in fall (68 percent) but season did not affect tag retention in brook trout. Loss of PIT tags of about 24 percent and 32 percent were observed in case of recaptured brook and brown trout, respectively, during the fall spawning season. Retention rate of PIT tags over two months was much lower for brown trout and brook trout tagged intraperitoneally (56 percent and 70 percent, respectively) than for those tagged in dorsal musculature (95 percent and 100 percent, respectively). Coastal cutthroat trout Oncorhynchus clarkii clarkii Tag retention rate was evaluated in wild populations of coastal cutthroat trout of about 100 mm (Bateman et al. 2009). A double- marking approach with removal of the adipose fin from all tagged fish was followed. Tag retention rates were 25 percent lower than other studies previously conducted on juvenile salmonids alone and some portion of tag loss was confirmed to be associated with spawning. Rainbow trout Oncorhynchusmykiss The short-term (≤1 week), annual (1 year), and long- term (≥1 year) retention rates of PIT tags placed in the peritoneal cavity of small resident rainbow trout was quantified and assessed in 11 study streams (Meyer et al. 2011). Significantly greater retention rates were noticed in rainbow trout longer than 100 mmmarked by experienced taggers than those marked by inexperienced ones, with high retention rates in both cases (98 percent and 95 percent, respectively). Annual retention rates for PIT tags averaged 81 percent among all study streams, ranging from a low of 67 percent to a high of 92 percent. Annual retention rates were lower for larger rainbow trout than for their smaller counterparts. PIT tag retention was lower in adult females than in adult males, possibly due to tag expulsion with eggs from the peritoneal cavity. Asp Leuciscus aspius Šmejkal et al. (2019) demonstrated the probability of PIT tag retention within the body cavity in relation to sh sex with a cystovarian type of ovulation (eggs do not enter the body cavity). After five years of monitoring, females had a grater probability of expelling internally implanted PIT tags than males. Retention rate were 85 percent in females vs. 98 percent in males. This study demonstrated that systematic bias may potentially occur as PIT tags may penetrate gonads and leave the body during reproduction. Role of PIT Tagging in Aquaculture To establish base population, diverse stocks of fish were collected from different riverine sources and hatcheries. These stocks were then tagged with PIT tags for individual identification and reared in communal ponds for growth evaluation. Full-sib and half-sib families thus produced in the nucleus breeding center from the base population and later from different generations were reared in separate nursery ponds and then PIT-tagged when they attained fingerling size of about 10-20 g. Tagging, therefore, enabled communal rearing of all families in one pond, reducing the pond effect common to full-sibs. During sampling, individual growth of fish could be monitored by recording initial length and weight to the corresponding PIT tag