On the bionomics and life history of the ell-like goby, Odontamblyopus rubicundus (Hamilton)

(1) Odontamblyopus rubicundus (IIamil.ton) is a red eel-shaped goby, abundantly found in the Ariake Sound, Kyushu (Fig. 1). (2) The observations on the internal and external body-features : fin-rays, scales, and alimentary duct, etc., were made on the collections from the Ariake Sound (Fig. 2～5). (3) This goby lives in the living-room constructed in the mud tidal flat deposit of the estuary. The room is tunnel-shaped, vertical and extending downward to a depth of 50-909 0 cm in the mud; with 4～9 zigzag holes communicating with the outside (Fig. 7～8). (4) The examination of the gut contents of 40 specimens ranging 200～300 mm in total length from the Ariake Sound showed that mud, young fishes, young shells, shrimps, and cattle fishes constituted the diet. The gut contents of the young, 20～60 mm in total length, were consisted of copepods and small shrimps. (5) The spawning-season extends from June to September in the Ariake Sound. The spawning habit and egg-development are yet unknown. The ripe egg discharged in the sea water is ellipsoid, 1.3 mm in long axis and 0.7 mm in short axis, with adhesive filaments at the basal end. There are many oilglobules in the semi-transparent, yellow yolk (Fig. 6). (6) The fact that the larvae, 4～20 mm in total length, were always collected by set-nets in the estuary proves that they are truly pelagic in habit. They were collected from July to October in the Ariake Sound (Fig. 9, A～F). The larvae, over 10 mm in total length were distingushed easily from the larvae of the allied species, Taenioides cirratus Blyth aud Ctenotrypauchen microcephalus (Bleeker), by the external features. (7) This goby seems to grow to 180 mm in total length in a year, and some individuals becomes mature in a year. The minimum adult is 150 mm in total length in both sexes. The life span seems to be over 3 years.ワラスボは日本, 朝鮮, 支那, 印変などの東南アジアの各地に分布していることが知らているハゼ類の一種であり, 日本では有明海に特に多い. 体はウナギ状をなして細長く, 生時の体色は淡紅色. 眼は退化して小さく, 皮下に埋没し, 背鰭, 尾鰭, 臀鰭の各鰭は一枚の鰭膜でもつて連なつているなど多くの点で特異な外形を示すハゼである. 有明海では各種の漁具によつてかなりの量が獲られ, 乾魚, 魚粉などにして食用とされるほかに養鶏の餌料としても用いられている. 筆者は1947年以来, 有明海においてワラスボの生態, 生活史について研究を行いその一部を知ることが出来たのでここに報告する