Verteilung und Nahrung des Ichthyoneuston im subtropischen Nordostatlantik

In four microlayers of the uppermost 60 cm of the subtropical NE Atlantic 477 samples of ichthyoneuston were collected. In at least 3 samples. 34 groups ( different taxa) of fish were discovered in the 0-10 cm layer. Among these groups there were 8 species of Beloniformes and 9 species of Myctophidae. Most of the fish were juveniles of 6-80 mm total length. The regional distribution, the vertical macrodistribution in 6 layers of the upper 200 m, 3 patterns of vertical microdistribution 6 patterns of diurnal migration, and 4 patterns of feeding activity are described. Most of the fish found in the 0-10 cm layer by day were small in size and appeared only in a few specimens per haul. The catches in the 0-10 cm microlayer were richer than those of the 10-25 cm microlayer, but poorer than those of the 0-30 m macrolayer. According to their gut contents the fish living at the surface could be divided into 3 main groups. In respect of the size and quality of food items, a competition for food was calculated. There is some evidence for a scarcity of food at the surface of the open subtropical Atlantic especially by day