The phytoplankton flora was poor in the Skagerrak area and small flagellated species dominated the samples. The integrated (0-20m) chlorophyll concentrations were low but within normal for this month. Traces from the spring bloom were obvious in the Kattegat area and the species Pseudochattonella sp., which is toxic for fish was blooming at N14 close to the coast and at Anholt E, farther out. The integrated (0-20m) chlorophyll concentrations were high but within normal for this month. At two of the Baltic stations, BY2 and Ref M1V1, the presence of several chain forming diatoms revealed that spring bloom was close. Apart from this, there were mostly small flagellates, ciliates and small spheric colony forming cyanobacteria in the phytoplankton samples. Enhanced integrated chlorophyll concentrations were found in the Southern Baltic.