Date of Award

2014

Degree Type

Thesis

Degree Name

M.Sc.

Department

Great Lakes Institute for Environmental Research

First Advisor

Fisk, Aaron T.

Keywords

Health and environmental sciences, Dusky shark, Life history, Muscle, Organochlorine, White shark

Rights

CC BY-NC-ND 4.0

Abstract

Sharks vary widely in life-history strategies, and possess unique lipid metabolism. Because of this diversity, and organochlorine (OC) lipid association, dynamics of OC accumulation in elasmobranch-rich ecosystems may be ineffectively predicted by the typically relied upon indicators, stable isotopes and body size. I compared ontogenetic OC profiles and concentrations between dusky ( Carcharhinus obscurus ) and white ( Carcharodon carcharias ) sharks. OC concentrations were elevated in the larger, higher trophic position (TP) white shark, but despite a tenably faster growth rate, ontogenetic diet shifts to mammal prey, and regional endothermy, slopes of growth-dilution corrected concentrations with age were equal between species. Similar ontogenetic TP increases, infrequent white shark seal predation, or inaccurate growth parameters are possible explanations. Inshore habitat use and mass varied in white and dusky sharks respectively with OC profiles and concentrations. TP and mass predicted interspecific concentrations and may therefore be considered reliable indicators of OC accumulation in these sharks.

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