Sex identification and PIT-tagging: tools and prospects for studying intersexual differences in freshwater fishes

K. Hulthén, B.B. Chapman, P.A. Nilsson, L.-A. Hansson, Christian Skov, Henrik Baktoft, J. Brodersen, C. Brönmark

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

This study evaluated a technique to allow the long-term monitoring of individual fishes of known sex in the wild using sex confirmation in close proximity to the reproductive period combined with individual tagging. Hundreds of partially migratory roach Rutilus rutilus were tagged with passive integrated transponders (PIT) following sex determination in spring and various performance
measures were compared with fish tagged outside the reproductive period in autumn. Short-term survival was >95% for R. rutilus sexed and tagged under natural field conditions. Total length (LT) did not affect the probability of survival within the size range tagged (119–280 m ), nor were there differences in timing of migration the following season between individuals sexed and tagged in
spring and individuals tagged in autumn (i.e. outside the reproductive period). Also, a similar per cent of R. rutilus sexed and tagged in spring and tagged in autumn migrated the following season (34·5 and 34·7%). Moreover, long-term recapture data revealed no significant differences in body condition between R. rutilus individuals sexed and tagged in spring, individuals tagged in autumn
and unmanipulated individuals. The observed sex ratio of recaptured fish did not differ from the expected values of equal recapture rates between males and females. Hence, there is no observable evidence for an adverse effect of tagging close to the reproductive period and therefore this method is suitable for studying intersexual differences and other phenotypic traits temporarily expressed during reproduction at the individual level in fishes
Original languageEnglish
JournalJournal of Fish Biology
Volume84
Pages (from-to)503-512
ISSN0022-1112
DOIs
Publication statusPublished - 2014

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