This document reports on the results of several models and sensitivities proposed at the 62nd meeting of the Scientific Committee (SC) of the IWC for the assessment of the Southern Hemisphere humpback whale Breeding Stock B, as well as some additional models and sensitivities that were proposed intersessionally. These models and sensitivities explore various stock structure hypotheses and alternative input data. Prior incoherence resulting from the implementation of genetic Nmin constraints was found to be a problem throughout the analyses, and the preferred way of including these constraints was the use of a global Nmin constraint for the Gabon and WSA regions combined. The estimated intrinsic growth rate for B1 ranges from 0.039 to 0.052 for the main models and 0.043 to 0.069 for B2. The estimated 2010 abundance relative to pristine level ranges from 0.508 to 0.750 for B1, and 0.045 to 0.124 for B2.