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Life history reconstruction and stock identification of Sockeye Salmon (Oncorhynchus nerka) using otolith trace element chemistry

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dc.contributor.author Penney, Zachary
dc.date.accessioned 2007-08-20T18:19:03Z
dc.date.available 2007-08-20T18:19:03Z
dc.date.copyright 2007 en_US
dc.date.issued 2007-08-20T18:19:03Z
dc.identifier.uri http://hdl.handle.net/1828/193
dc.description.abstract Recent advances in otolith microchemistry have established that trace element composition can be used to chemically reconstruct fish life history and serve as a stock identification tool. In modern fisheries practices, these two applications are especially pertinent to wild salmon populations, which are difficult to track over large spatial scales and nearly impossible to identify in mixed populations. This project has applied a novel method using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to anadromous sockeye salmon (Oncorhynchus nerka) otoliths from four separate watersheds in Sitka, Alaska. Spatial distributions of Li, Mg, Mn, Zn, Sr, and Ba were determined via continuous lateral ablation scans across the diameter of transversely sectioned sagittal otoliths. Time-series data generated from line scan analysis were used to chemically reconstruct sockeye life history, and examine elemental signatures in the core, freshwater, and marine growth regions of otoliths for stock identification purposes. Chemical profiles of life history showed that Sr, Ba, and to a lesser degree Mg, reflected ambient chemistry, and were effective for tracking sockeye migration from fresh to marine water. Manganese was also effective for determining migration to fresh and marine water; however, it is believed that diet more than ambient chemistry is the factor controlling uptake. Elements such as Zn and Li provided information related to fish physiology, such as growth and changes in osmoregulation during transitions from low to high salinity environments. Results also showed that several elements were either enriched or depleted in the core of sockeye otoliths. Maternal investments and spatial differences in crystal structure are believed to significantly affect element uptake in otoliths during incubation and early development. Elemental signatures in the otolith core may therefore be inaccurate as an indicator of stock origin. This problem was investigated by isolating core, freshwater, and marine signatures and evaluating individually their ability to correctly classify sockeye otoliths to their natal watersheds using step-wise discriminant function analysis. This demonstrated that freshwater signatures provided the greatest accuracy (91%) for stock ID. Core signatures, which have been used in past stock ID studies, showed poor classification results (68%) for sockeye salmon otoliths. Trace element signatures from the marine growth regions of sockeye otoliths displayed the poorest classification accuracy (52.5%) of the three growth regions. Thus, freshwater signatures are the most effective tool for identifying the origin of wild salmon, even when they far removed from their natal watersheds. en_US
dc.language English eng
dc.language.iso en en_US
dc.rights Available to the World Wide Web en_US
dc.subject Otolith en_US
dc.subject Sockeye salmon en_US
dc.subject trace element en_US
dc.subject chemistry en_US
dc.subject stock identification en_US
dc.subject life history en_US
dc.subject.lcsh UVic Subject Index::Sciences and Engineering::Earth and Ocean Sciences en_US
dc.title Life history reconstruction and stock identification of Sockeye Salmon (Oncorhynchus nerka) using otolith trace element chemistry en_US
dc.type Thesis en_US
dc.contributor.supervisor Telmer, Kevin
dc.degree.department School of Earth and Ocean Sciences en_US
dc.degree.level Master of Science M.Sc. en_US


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