RV Platessa tagged plaice were released off the Cumberland coast, using the RV "Platessa" during 1949 and 1950. In August 1951 echo-sounder traces were obtained over a wide area off Whitby by the RV 'Platessa', using a Marconi sounder. They were found to occur at a depth corresponding to that of a sharp thermocline, and small whiting about 3 in. in length, large Medusae, herring and sandeel larvæ were caught with a pelagic trawl at the depth of the trace. This work was reported in a ‘letter’ to the journal Nature in 1952. In 1950 the RV "Platessa" was involved in comparative
RV Platessa in survey logbooks, collected in 1931, 1937, 1946–50, and 1968. These historical measurements have revealed that the ‘sechhi depth’ was much deeper (and therefore water more transparent) in the past compared to today, and thus that the North Sea has become much more turbid. The Suffolk Record Office holds a photograph captioned ""survey ship "Platessa" LT 205 in Lowestoft harbour after being escorted back by the Gorleston lifeboat Khami having sprung a leak whilst working in the Smiths Knoll area"", dated 5th October 1968 (after leaving MAFF service). RV Platessa RV "Platessa" (LT205) was a fisheries research vessel that was