  Operationally accessible entanglement in bipartite systems of
indistinguishable particles could be reduced due to restrictions on the allowed
local operations as a result of particle number conservation. In order to
quantify this effect, Wiseman and Vaccaro [Phys. Rev. Lett. 91, 097902 (2003)]
introduced an operational measure of the von Neumann entanglement entropy.
Motivated by advances in measuring R\'enyi entropies in quantum many-body
systems subject to conservation laws, we derive a generalization of the
operational entanglement that is both computationally and experimentally
accessible. Using the Widom theorem, we investigate its scaling with the size
of a spatial subregion for free fermions and find a logarithmically violated
area law scaling, similar to the spatial entanglement entropy, with at most, a
double-log leading-order correction. A modification of the correlation matrix
method confirms our findings in systems of up to $10^5$ particles.
