A Summary of the Observations on the Occurrence of Planktonic Stages of Fish off Plymouth 1924–1972

Records of the occurrence of postlarval stages of teleostean fishes in the plankton off Plymouth have been kept for a period of nearly 50 years. During that period noteworthy changes in the abundance of postlarvae have taken place. While in the 1920s postlarvae were very abundant in the plankton, in the 1930s they became much fewer at about the time when the herring fishery declined. Somewhere around 1965 another change took place and post-larvae became once more very abundant. There was also a marked increase in the quantity of macroplankton, which like the young fish had become much reduced in quantity in the 1930s (Russell et al. 1971).