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
Anyperodon than the upper jaw. There are no palatine teeth, a fact which distinguishes this species from other groupers. The basic colour is pale reddish-brown liberally dotted with orange spots which are closer together on the head. There are five pale silvery blue longitudinal lines running down either side, the lower 3 reaching the tail but the upper two breaking into irregular streaks. The dorsal fin has 11 spines and 14 to 16 soft rays. The anal fin has 3 spines and 8 to 9 soft rays. Juvenile fish have vivid blue and red longitudinal stripes. The slender grouper has a