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Exploring trends, causes, and consequences of declining lipids in Lake Superior lake trout
Citation:
Sierszen, M., M. Vinson, C. Harvey, J. Myers, AND D. Yule. Exploring trends, causes, and consequences of declining lipids in Lake Superior lake trout. Association for Sciences of Limnology and Oceanography, Santa Fe, NM, June 05 - 10, 2016.
Impact/Purpose:
not applicable
Description:
The ability of lake trout to forage in deepwater habitats is facilitated by high lipid content, which affords buoyancy. In Lake Superior, lean lake trout historically occupied depths < 80 m, and siscowet lake trout occupied depths > 80 m. Siscowets have been known for their high lipid content (in excess of 65% in filets) which assists in diel vertical migration, an important adaptation to life in profundal habitats. In recent years several lines of evidence suggest that lipid concentrations in Great Lakes lake trout have declined. To explore changes in lipids and their energetic consequences, we compared lipid content and swimming costs in lean and siscowet lake trout collected in 1953-1963, 1997, and 2013. We also examined trends in lean and siscowet depth distributions. We found declines in filet lipid content of lean and siscowet lake trout across years. Especially high declines in siscowets resulted in near-doubling of swimming costs that may challenge their ability to forage in deep habitats. Siscowet have increasingly been found in shallower, nearshore waters over the past decades.