The file "traffic.txt" contains a matrix of pairwise flows among global ports estimated using methods described in Drake & Lodge (2004). Flow units are ships per year obtained by rescaling shipping tonnage as described by (Drake & Lodge 2004).

The file "port_locations2.txt" contains geographic coordinates ordered to coincide with the matrix in the first file and (unofficial) place names.

These data are not raw data, but interpolated estimates obtained from the gravity model described in Drake & Lodge (2004). They are provided free and without warranty for any reasonable use. We request that any publication resulting from further analysis cite (Drake & Lodge 2004), while the ISL report (Zachcial & Heideloff 2001) should be cited as the source of the raw data. Questions and/or requests for other material should be directed to Dr. John Drake, Odum School of Ecology, University of Georgia (jdrake@uga.edu).

Drake, J.M & D.M. Lodge. 2004. Global hotspots of biological invasions: evaluating options for ballast-water management. Proceedings of the Royal Society, Series B 271:575-580.

Zachcial, M. & Heideloff, C. 2001 ISL shipping statistics yearbook 2001. Bremen, Germany: Institute of Shipping Economics
and Logistics.