Juvenile Saury Pike (Scomberesox Saurus Walb.), an Example of Ichthyoneuston

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Abstract
In April and July 1967, 354 samples of the upper 60 cm of the sea were collected with a David-neuston net in the subtropical North-East Atlantic. S. saurus (6–113 mm total length) was the most abundant fish in the collection. In the microlayer of about 0–10 cm the number of S. saurus taken was 12 times larger than in the two adjacent layers (about 10–25 cm, 38–53 cm). While smaller S. saurus (6–29 mm) stay permanently in the 0–10 cm layer, middle sized fish (50–113 mm) were found there only at night. Gonads of S. saurus of more than 62 mm contained immature eggs of 2 mm diameter. Analysis of the gut contents showed 4 ontogenetic stages: Protozoa-gastropods-stage (6–15 mm), gastropods-entomostraca-stage (16–30 mm), entomostraca-stage (31–45 mm) and crustaceans-stage (46–113 mm). The size range of the food was determined by measuring the shells of atlantids (planktonic heteropod gastropods). Dominance of juveniles in subtropical ichthyoneuston can be understood as an outcome of physical conditions at the surface and as a convergence to nanism of sargassum fauna.

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