Acknowledgements We thank the crew members of the R/V
Harold Streeter for safe collection of sharks throughout this
research; and S. Larson, J. Christiansen, J. Hollander, D. Farrer
and G. Bargmann for collaborative efforts during our sixgill
research. Three anonymous reviewers provided helpful
comments to improve the content of this manuscript. PSL
thanks R. Hesjedal for his preparation and professionalism.
This work was supported by the NOAA Northwest Fisheries
Science Center