On the partition function of the $Sp(2n)$ integrable vertex model

We study the partition function per site of the integrable $Sp(2n)$ vertex model on the square lattice. We establish a set of transfer matrix fusion relations for this model. The solution of these functional relations in the thermodynamic limit allows us to compute the partition function per site of the fundamental $Sp(2n)$ representation of the vertex model. In addition, we also obtain the partition function of vertex models mixing the fundamental with other representations.