4. The right of several fishery granted by article 3 is subject to the following restrictions—
(a)that the harvesting of scallops must be carried out manually by divers; and
(b)that the grantee must not without the written consent of the Scottish Ministers deposit within the boundaries of the fishery any juvenile scallop taken from outwith the fishery and must comply with any condition subject to which the Scottish Ministers give such consent.