A Field Experiment with Drifting Hoop Nets to Collect the Small Fish Gathering around Drift Algae

Abstract

A field experiment with drifting hoop nets was carried out in the coastal water of the Kuroshio during 6–12 August 1977 in order to collect the small fish associated with drift algae. Two types of drifting hoop nets composed of 5 large (0.83 m3) and small (0.22 m3) hoop nets were released about 50 miles off Shikoku on 6 August and tracked; each type was retrieved twice during the tracking to catch the fish in the nets. The juvenile and young fish of 9 species (7 families) were collected including Arothron firmamentum (467 ind.), Abudefduf vaigiensis (71 ind.), Thamnaconus modestus (70 ind.) and Decapterus maruadsi (8 ind.). The greater part of the fish were collected with 7 mm mesh large nets. T. modestus and D. maruadsi were mostly collected at a depth of about 13 m in contrast to A. vaigiensis and A. firmomentum which were collected at the surface. Body lengths (ranging 80–108 mm in BL) of T. modestus were somewhat larger than previously reported. The appearance of young A. firmamentum suggests that they possibly migrated in and around the Kuroshio Current off Shikoku during the period of this experiment. © 1988, The Japanese Society of Fisheries Science. All rights reserved.