Validation of otolith δ18O values as effective natural tags for shelf-scale geolocation of migrating fish

Type Article
Date 2018-06
Language English
Author(s) Darnaude Audrey M.1, 2, Hunter EwanORCID2, 3
Affiliation(s) 1 : Univ Montpellier, UMR MARBEC 9190, CNRS, Pl Eugene Bataillon, F-34095 Montpellier, France.
2 : Lowestoft Lab, Ctr Environm Fisheries & Aquaculture Sci, Lowestoft NR33 0HT, Suffolk, England.
3 : Univ East Anglia, Sch Environm Sci, Norwich Res Pk, Norwich NR4 7TJ, Norfolk, England.
Meeting ICES Annual Science Conference, Riga, LATVIA, 2016
Source Marine Ecology Progress Series (0171-8630) (Inter-research), 2018-06 , Vol. 598 , P. 167-185
DOI 10.3354/meps12302
WOS© Times Cited 21
Keyword(s) Fish migration, Oxygen, Stable isotopes, Natural tag, Site fidelity, Plaice, Pleuronectes platessa

The oxygen isotopic ratio of fish otoliths is increasingly used as a 'natural tag' to assess provenance in migratory species, with the assumption that variations in delta O-18 values closely reflect individual ambient experience of temperature and/or salinity. We employed archival tag data and otoliths collected from a shelf-scale study of the spatial dynamics of North Sea plaice Pleuronectes platessa L., to examine the limits of otolith delta O-18-based geolocation of fish during their annual migrations. Detailed intra-annual otolith delta O-18 measurements for 1997-1999 from individuals of 3 distinct sub-stocks with different spawning locations were compared with delta O-18 values predicted at the monthly, seasonal and annual scales, using predicted sub-stock specific temperatures and salinities over the same years. Spatio-temporal variation in expected delta O-18 values (-0.23 to 2.94%) mainly reflected variation in temperature, and among-zone discrimination potential using otolith delta O-18 varied greatly by temporal scale and by time of year. Measured otolith delta O-18 values (-0.71 to 3.09%) largely mirrored seasonally predicted values, but occasionally fell outside expected delta O-18 ranges. Where mismatches were observed, differences among sub-stocks were consistently greater than predicted, suggesting that in plaice, differential sub-stock growth rates and physiological effects during oxygen fractionation enhance geolocation potential using otolith delta O-18. Comparing intra-annual delta O-18 values over several consecutive years for individuals with contrasted migratory patterns corroborated a high degree of feeding and spawning site fidelity irrespective of the sub-stock. Informed interpretation of otolith delta O-18 values can therefore provide relatively detailed fisheries-relevant data not readily obtained by conventional means.

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