  We consider Steklov eigenvalues of three-dimensional, nearly-spherical
domains. In previous work, we have shown that the Steklov eigenvalues are
analytic functions of the domain perturbation parameter. Here, we compute the
first-order term of the asymptotic expansion, which can explicitly be written
in terms of the Wigner 3-jsymbols. We analyze the asymptotic expansion and
prove the isoperimetric result that, if l is a square integer, the
volume-normalized l-th Steklov eigenvalue is stationary for a ball.
