Holt joined the Marine Biological Association (MBA) and worked until 1894 at Grimsby, where he was in charge of a newly opened research station for the North Sea. After a brief stint at the "Station zoologique d'Endoume" at Marseille he then worked for three years at the Plymouth Marine Laboratory. Nevertheless, E. W. L. Holt maintained his ties with Ireland, and in 1895 he purchased a dismasted brigantine named "Saturn" for the Royal Dublin Society and had it equipped as a marine biology research station. In 1899, he returned to Ireland, taking charge of the "Saturn" and her four small auxiliary sailing boats used for sampling. The floating laboratory was stationed in the Connemara district in County Galway; it lay at Ballynakill in winter and was towed to Inishbofin for the summer months. In 1900, the "Saturn" was transferred to the new Department of Agriculture and Technical Instruction for Ireland. Green became Chief Inspector of its Fisheries Branch; Holt was at first scientific advisor and later, as of 1908, Fisheries Inspector. They were joined by other young biologists, among them Rowland Southern and George Philip Farrar.