World Aquaculture Magazine -December 2021

WWW.WA S .ORG • WORLD AQUACULTURE • DECEMBER 2021 61 rates but also maximize the speed of wound healing. Some of the studies on effect of growth and physiology in different species are summarized as follows: Rohu Labeo rohita Under an Indo-Norwegian project, the efficacy of PIT tags for marking rohu during the selective breeding programwas carried out. Six groups of rohu fingerlings (2-20 g) were PIT tagged for determination of the suitable size range for tagging. Results indicated that 8-15 g fingerlings were suitable for PIT tagging, with a tag rejection rate of only 0.05 percent (Mahapatra et al . 2001). Atlantic salmon Salmo salar There was no post-surgery mortality or tag shedding in Atlantic salmon when PIT tags were inserted into the peritoneal cavity (Roussel et al . 2000). Foldvik and Kvingedal (2018) studied 12-mm PIT tag retention rates in hatchery-reared Atlantic salmon over a 533-day period from the late juvenile freshwater stage (pre-smolts) to young adults after one year in seawater. Tag retention was 91 percent and was lowest in the period following tagging (days 0–49) and then increased substantially before again dropping close to initial levels in the two last periods (days 173–533). Chinook salmon Oncorhynchus tshawytscha Knudsen et al. (2009), in a double-tag study test, tagged juvenile upper Yakima River hatchery spring Chinook salmon with PIT and coded wire snout tags to test the retention and effect of PIT tags on post-release survival, behavior and growth. The average loss of PIT tags was 2 percent in juveniles before release and 18 percent in recaptures returning 6 months to 4 years after release. Smolt- to-adult recruit survival of PIT-tagged fish was significantly lower than non-PIT-tagged fish because of loss of tags and reduced survival, resulting in an average underestimate of survival of 25 percent. Mean lengths and weights of PIT-tagged adults were less than those of non- PIT-tagged adults in all age comparisons. Coho salmon Oncorhynchus kisutch Prentice et al . (1994) used a double-tag study design to estimate PIT tag loss and observed that mature adult coho salmon PIT-tagged as juveniles lost their tags at high rates before spawning, and estimated overall tag loss rates of 59 percent in females and 13 percent in males. This difference in rates of tag loss in males and females may be related to changes in gamete development at full maturity. The fork length of PIT-tagged adults was significantly smaller (by 2 cm) than that of the non-PIT-tagged adults. Eurasian perch Percafluviatilis Baras et al. (2000) conducted an experiment to determine the minimum size of tagging and evaluate surgical implantation in juvenile perch of size range 2-11 g (55–96 mm FL). Juvenile perch as small as 2 g can be confidently tagged and the tagging protocol, tag presence or tag to body weight ratio did not affect survival, gonadal development and abdominal fat storage capacity of tagged perch. No internal damage or tag expulsion was noticed. The negative effects were only limited to early growth impairment and slower healing rate during the first post-tagging days, which was later compensated within less than two weeks. Brook trout Salvelinus fontinalis and brown trout Salmo trutta Dieterman and Hoxmeier (2009) examined effects of tagging season, anatomical placement of tags, and fish total length at tagging FIGURE 4. General workflow of fish tagging with PIT tags (Photos: A. Rasal and M. Patnaik). ( C O N T I N U E D O N P A G E 6 2 )