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シロウリガイ類飼育の試み
三宅 裕志(1),(2)※, 山本 啓之(2), 北田 貢(1), 植田 育男(1), 大越 健嗣(3), 喜多村 稔(2), 松山 和世(2), 土田 真二(2)
(1)新江ノ島水族館　 (2)海洋研究開発機構 　(3)石巻専修大学

Abstract． There have been no reports on rearing deep-sea giant white clams of the genus Calyptogena. Here we report on the first attempt to rear Calyptogena. To date,we have been able to keep samples alive for a few days after sampling. In order to keep Calyptogena in good condition and to reproduce their natural environment as closely as possible (excepting water pressure), a MT push core was developed. In addition, a Dissolved Oxygen Concentration Control System (DOCCS) was developed to keep Calyptogena specimens at a low dissolved oxygen concentration, as found in their habitat.
Calyptogena soyoae and Calyptogena solidissima were collected at depths of 1,150m〜1,160m, off Hatsushima, Sagami Bay and at a depth of 643m, Kuroshima Knoll, off Ishigaki Island, respectively. C. soyoae were kept alive in captivity for one week, while C. solidissima were kept alive for 17 days. Spawning of C. solidissima has been observed on two occasions during their captivity in aquaria. It appears that C. solidissima is the easiest species of the genus Calyptogena to rear and breed in aquaria.

要旨 シロウリガイ類は深海から採集すると通常2，3日しか生存せず，飼育を試みた報告は皆無であった．本研究では，シロウリガイ類の飼育の試みとして，良好な健康状態で採集し，かつシロウリガイ類の共生細菌のエネルギー源(泥中の硫化水素)を確保するために，圧力以外の現場環境をできる限り維持した状態で採集する装置のMTコアを開発した．また，シロウリガイ類は高酸素濃度に弱いため，溶存酸素濃度制御装置により低酸素濃度環境を維持する飼育システムを製作した．シロウリガイとエンセイシロウリガイをそれぞれ相模湾初島沖水深1,150m〜1,160mの地点, 石垣島沖の黒島海丘の643mの地点で採集した．採集したシロウリガイは約1週間で死亡したが，黒島海丘のエンセイシロウリガイは17日間生存した．また，エンセイシロウリガイでは2回放卵が確認された．以上のことから，エンセイシロウリガイは飼育が容易な種と考えられた．