大村湾のテンジクダイ

The author studied the morphological characters and the feeding habits of Apogon lineatus in Ômura-Bay which were caught by the shrimp drag nets in the last six years. The results obtained are as follows: 1. Among the cardinal fishes in Ômura-Bay, Apogon lineatus is the most common, while A. semilineatus, A. kiensis, and A. niger are seen scarcely. Apogonichthys carinatus is found in Ainoura-Bay, but not in Omura-Bay. 2. From the view of monthly changes of body length, the life span of A. lin. is supposed as one year. The max. length of female is 78mm and that of male is 74mm. The relation of the total length to the body length is well shown by the following formula, TL=BL×1.23 (in mm). 3. The growth rate is different between male and female, namely that of female is faster than male, and there is about 10mm difference in body length in one year. 4. Both sexes of A. lin. in Ainoura-Bay are ca. 5mm bigger than those in Ômura-Bay. 5. Body weight shows its max. in August and min. in February. 6. The dentition on the club-shaped gill rakers of male specimens are covered with soft muscular membrane at their spawning season. 7. The spawning season extends from July to October, and its peak occurs in August. At that time the ovary grows very large, while the testis is very small and less than 1/200 of the ovary in weight. 8. Number of gill rakers of first gill arch is commonly 14 (upper 3, lower 11) except small prickles; number of pyrolic appendages is 3; and number of vertebrae is 23. 9. Isthmus of almost all male specimens protrude oddly at the spawning season. 10. A. lin. is carnivorous and from its predacious habit it seems that it is living a little above the sea bottom. 11. Male specimens eat eggs of their own relatives at their spawning season without exception, and it is presumably regarded that the male will swallow a part of eggs when they accept the eggs in their mouth to breed. At this season no other food are eaten by the male, but in the case of female small crustaceans are eaten abundantly.

1.大村湾内のApogonidaeはテンジクダイを主とし,その他ネンブツダイ,テツポウイシモチ,クロイシモチが僅か見られた。近接した相浦湾にはマトイシモチが少くないが,大村湾には見られない。2.体長の月別頻度分布からテンジクダイは一年魚であるとした。今までに大村湾で得られた最大のものは♀78mm,♂74mmであつた。全長と体長との関係はTL=BL×1.2+3(mm)で表わされる。3.♀♂ で成長が異り,♀ の方が速く,一年間に約10mmの差が生ずる。4.相浦湾と大村湾では前者の方が♀♂共に約5mm大きい。5.同じ体長のものゝ体重は2月が最小8月が最大となる。6.幽門垂は大小合せて3本， 脊椎骨数23,第一鰓弓の鰓把は上肢3下肢11計14が最も普通(たゞしprickleを除く)。7.産卵期は7月から10月中旬で,8月が最盛期,卵巣は体重の1/5に達する大きいものがあるが,精巣は甚だ小く,卵巣の1/200以下である。8.産卵期には♂ の鰓把上の小刺列が袋を被る。これは口中抱卵の卵を傷けぬための自然の適応であろう。9・産卵期の♂ は峡部著しく膨出し,奇型を呈する。♀にも若干見られ,♀ の口内抱卵も稀には存在するものと推測される。10.食餌は全く動物性のもので,その種類から見てテンジクダイは底上魚の性質を示す。11.♂ は産卵期には口中抱卵のため全く餌を食つていないが,同族の卵をほとんど例外なくその胃中に発見する。♀は卵を食することはなく,甲殻類などの天然餌料を盛んに摂食している.