Ballast water source and management type for all vessels in pre- and post-management eras.

By era shown are: (a) contribution of managed BW for each source region as a percentage of total managed BW, and (b) percentage contribution of BW management methods within each source region. (FT = flow through, ER = empty-refill, None = no management, PU = the ballast tank was pressed up; here water was added to completely fill the tank in mid-voyage). If no vessels of a certain category were sampled this is denoted with a ‘-‘.