Development and application of a small Pop-up Tag using the ARGOS satellite data transfer system for obseving the behavior of aquatic animals

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The three years of research of this project has resulted in the development of a small pop-up tag (PUT) using the ARGOS satellite data transfer system for observing the behavior of fishes and aquatic animals, and in 2002, the last year of the project, we attached prototype PUTs to migratory phase freshwater eels and released them during an experimental test of the tags. The primary results of this research to develop PUT are summarized as follows:1. We minimized an ARGOS transmitter that is a main part of a PUT, to the small size of 55.0 x 13.5 x 6.0 mm, and mounted it along with a battery, pressure sensor and thermometer within a cylindrical pressure resistant carbon FRP case that was 143 mm long and 17.2 mmφ. The antenna for transmitting the data to the satellite was 210 mm long and so the total length of the PUT was 353 mm. Outside the PUT, a specially designed cutter (30 x 8 mm) was attached to release the tag from the fish.2. On 28 November 2002, we attached a PUT on two silver stage Japanese eels, Anguilla japonica, during their spawning migration and released them in the Tone River estuary. The timing of pop up for each of the two tags was set at 5 and 15 days after release. Although the 5-day tag was lost after release, we successfully obtained data from the 15-day tag and confirmed the ability of the PUT to transmit data by satellite.3. After three years of research we attained the scheduled goal of developing PUT, although we need a small modification of the data transmission system. We plan to make an additional experimental field release and refine the system, and after a few years, we will make commercial products.