Novel method of tagging the kuruma prawn Penaeus japonicus with a trans-molting retentive external eye (TRAMORE) tag

Abstract

An easily applicable, economical, and reliable tagging method, without risk to consumers, is required for the kuruma prawn Penaeus japonicus. This report describes the development of external tags for the kuruma prawn. Two types of external tag, differing slightly in form, were developed. Tests were performed to determine whether these external tags were retained after molting and whether the tagging method affected survival and growth in the laboratory. One type of external tag, with a hole of diameter 1.5 mm, was applied to the eyestalks of juvenile prawns approximately 45 mm in body length (BL). Despite repeated molting, these tags were retained at least until the prawns grew to BL 140 mm. Therefore, these tags were called trans-molting retentive external eye (TRAMORE) tags. The trackable size range with the TRAMORE tag, with a hole of diameter 1.5 mm, (<140 mm BL) covered approximately 50 % of kuruma prawns caught in Seto Island Sea, Japan, one of its main fishing grounds. The TRAMORE tag had no impact on the survival, growth, or molting frequency of juveniles. The second type of TRAMORE tag, with a hole of diameter 2.8 mm, was not shed during molting of individuals of BL ranging from 82.7 mm to 216 mm BL. Approximately 100 % of kuruma prawns caught in Seto Island Sea were of this size. The TRAMORE tag would contribute to kuruma prawn stock enhancement programs and investigations of key aspects of its ecology.