Evaluation of a fluorescent, alphanumeric tagging system for penaeid shrimp and its application in selective breeding programs

The ability to monitor performance of individual shrimp cultured under commercial growout conditions would provide researchers with a valuable tool to use in selective breeding programs. The objective of this study was to evaluate tag retention and readability of two sizes (standard format 1.0×2.5 mm and large format 1.5×3.5 mm) of the Visible Implant Alphanumeric (VI-alpha) tagging system (Northwest Marine Technology) in juvenile and sub-adult Pacific white shrimp, Litopenaeus vannamei, reared under laboratory and field conditions. VI-alpha tags are soft fluorescent tags with an alphanumeric coding system which provides individual identification and is implanted beneath clear tissue so that it can be read externally. For juvenile (mean weight 2.7 g) and sub-adult shrimp (mean weight 21.5 g), tags were inserted through the ventral surface of the abdomen and shrimp were maintained in either laboratory or field environments for evaluation. During the study, each experimental group was weighed and evaluated for tag retention and readability. For juvenile shrimp in the laboratory, overall tag retention was 95% for both tag sizes with 82% readability after shrimp exhibited a mean weight gain of 10.5 g over 42 days. Under field conditions, there was a 70.5% recovery of tagged juveniles with 81% readability after shrimp exhibited a mean weight gain of 21.1 g over 140 days. For sub-adult shrimp in the laboratory, overall tag retention was 99.2% for both tag sizes with 95% readability after a mean weight gain of 4.7 g over 75 days. Under field conditions, there was an 84% recovery of tagged sub-adults with 84% readability after a mean weight gain of 20 g over 110 days. These results indicate that the soft VI-alpha tagging system evaluated in this study is a valuable research tool with applications in selective breeding programs. The ability to monitor individual shrimp performance could lead to greater selection intensity, improve the accuracy of breeding values, and provide information that may be used to calculate heritability estimates by offspring/parent regression.