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Otolith chemistry discriminates water mass occupancy of Arctic fish in the Chukchi Sea

Gleason, Christine M., Norcross, Brenda L., Spaleta, Karen J.
Marine & freshwater research 2016 v.67 no.7 pp. 967-979
Boreogadus saida, Gymnocanthus tricuspis, age structure, barium, calcium, chemistry, habitat preferences, habitats, magnesium, marine fish, otoliths, strontium, water temperature, Arctic region, Chukchi Sea
The microchemistry of otoliths has the potential to reconstruct fish movement patterns and habitat use between environmentally different habitats for individual age classes of Arctic marine fish. Herein, we tested the relationship between the bottom water mass from which a fish was collected and the microchemistry of the most recent growth edge of the fish’s otolith using Mg, Sr, Ba and Ca, and then determined the physical and biological factors that affected the chemical signatures. A discriminant function post hoc analysis of fish occupying bottom water masses resulted in 76% correct classification of Arctic or Polar cod (Boreogadus saida) and 82% correct classification of Arctic staghorn sculpin (Gymnocanthus tricuspis) into bottom water masses of capture when ages were pooled. By separating age classes, correct classifications into water masses of capture were as high as 87% for Arctic cod (three water masses) and 90% for Arctic staghorn sculpin (two water masses). Otolith Ba:Ca, Mg:Ca and Sr:Ca ratios were most consistently affected by bottom water temperature; the latter two were also affected by fish age and fish length. The use of otolith microchemistry to determine occupancy of water masses over time is most promising for Arctic cod, which is widespread and occupies the most thermally diverse habitats in Arctic waters.