  By considering full-field string solutions of the Abelian--Higgs model, we
modify the model of a fluid of strings (which is composed of Nambu strings) to
obtain a model for a ``fluid of vortices.'' With this model, and following
closely Soleng's proposal of a fluid of strings as the source of a Milgrom-type
correction to the Newton dynamics, we determine quantitatively the modified
dynamics generated by a static, spherical fluid of vortices.
