Whole salmon scales were analysed using inductively coupled plasma mass spectrometry (ICP-MS) to test for differences in elemental compositions between salmon stocks. The investigation was structured to address stock variation based on fish origin (wild or farmed), farm populations, river origin of wild fish and sea fishery origin (Farces or Greenland). Initial studies were conducted to determine optimal analytical methods and to quantify the effects of fish size, sex, age and interannual variability on trace element composition within a single stock. Although a large number of trace elements were measured in fish scales, only a small number were found to be important predictor elements. The trace element composition of scale samples from wild and farmed fish enabled identification of origin (wild/farmed) to a high degree of accuracy (98 %), with Mn found in significantly higher concentrations in farmed fish and identified as the most influential element. Farmed fish taken from six sites around the west coast of Scotland were also correctly classified with a surprisingly high accuracy using discriminant analysis (87 %). The ability to discriminate between wild stocks was tested using scales from returning fish caught in 12 rivers from around Scotland. Overall classification success was 59 %, but this was found to depend on sample sizes, with elimination of samples comprised of small numbers of individuals improving the classification success to 90 %. The elements showing the highest predictive power differ according to the origin of fish, Mn carries most weight distinguishing farmed from wild fish, Ba, Mn, Zn, Co, Li, Ni and V are important in distinguishing between farms, Li, Sr and Ba strongly influence classification of wild wish and U was found to be the most important predictor element separating out samples recovered from the Farces and West Greenland fisheries. It is suggested that differences in Li and Ba i Abstract contents in scales reflect natural differences in river or catchment water chemistry, Zn, Ni, Co and V are likely to reflect differences in anthropogenic loading within industrialised settings and the high levels of Mn found in farmed fish scales predominantly reflects dietary uptake from supplementation of feed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:445141 |
| Date | January 2007 |
| Creators | Adey, Elizabeth Alys |
| Contributors | Black, Kenneth ; Shimmield, Tracy M. ; Trueman, Clive |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=239555 |
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