The capital sum fixed by such deed of agreement or by the award of the arbiter shall be raised and provided by the persons resident in the parish who are liable in payment of fish teinds, and shall, under the direction of the sheriff and of the procurator and agent of the Church of Scotland, be invested on approved heritable security, in the names of the moderator and clerk of the presbytery and of the procurator of the said Church, all for the time being, and their successors in office, as trustees for the management of the said capital sum; and the said trustees shall, after deduction of any necessary expenses, pay over half-yearly the interest accruing on the said capital sum to the minister of the parish for the time being; and they may from time to time change the said security, and re-invest the said capital sum on approved heritable security in the names of the trustees for the time being.