  The moment of inertia, Theta, is one of the possible observables for the
experimental determination whether a trapped Fermi system has reached the BCS
transition or not. In this article we investigate in detail the temperature
dependence of Theta below the critical temperature T_c. Special care is taken
to account for the small size of the system, i.e., for the fact that the
trapping frequency hbar omega is of the same order of magnitude as the gap
Delta. It is shown that the usual transport approach, corresponding to the
leading order of an expansion in powers of hbar, is not accurate in this case.
It turns out that Theta does not change rapidly if T becomes smaller than T_c,
but it rather decreases slowly. Qualitatively this behavior can be explained
within the two-fluid model, which again corresponds to the leading order in
hbar. Quantitatively we find deviations from the two-fluid model due to the
small system size.
