1982 Ayres, PA. Plankton blooms of economic importance to fisheries in UK waters 1968-1982 dataset https://portal.medin.org.uk/portal/start.php?tpc=010_2c87b4d3a05204d75f6717e4a4dbce06 Three phytoplankton species blooms which have been reported harmful to fisheries in UK waters are discussed: (1) The armoured dinoflagellate Gonyaulax tamarensis has caused harmful levels to humans of paralytic shellfish poison in most years since 1968 in shellfish from sites on the British east coast between 54.5°N and 56.7°N. The months of maximum toxicity are May and June. (2) Red tides of the naked dinoflagellate Gyrodinium aureolum have caused mortalities of wild marine animals in south-west England in 1978 and in North Wales in 1971, and killed farmed salmon in the west of Scotland in 1980. These red tides occurred between August and October. The dinoflagellate occurs all along the west coast of Britain and is often abundant at fronts. (3) Blooms of 'flagellate X', possibly a species of Olisthodiscus or Chattonella, have killed farmed fish in sea-lochs on the west coast of Scotland in 1979 and 1982. 20160219