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本邦産マイワシの研究―1 : 成熟度 (2)群成熟度

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Title: 本邦産マイワシの研究―1 : 成熟度 (2)群成熟度
Other Titles: Studies on the Japanese Sardine―I.Maturity (2), Maturity of Fish Shoal
Authors: 田村, 修
Authors (alternative): Tamura, Osamu
Issue Date: 30-Nov-1959
Publisher: 長崎大学水産学部
Citation: 長崎大学水産学部研究報告, v.8, pp.250-258; 1959
Abstract: The 11 shoals of sardine taken from the southern area of the Japan Sea in February~April of 1939 were examined mainly in respect to the relationships between the maturity (ovaries) of shoal and the age, the body length, the water temperature and the corpulency. 1 The rate of maturity of female fish group in each shoal are designated by the histograms of the percentage of each class of the selected egg diameter. 2 The older fishes have the higher percentage of individuals of the perfectly ripening eggs and the higher rate of maturity. 3 The fishes of larger than 20 cm of body length spawn in abundance more than those of the smaller. 4 The rate of the spawning of these fish group in the season may be expressed by the sum of the perventage of the fishes having ovary of the smallest egg diameter and that of the fishes having eggs larger than 1.0 mm. 5 The rate of spawning can be presumed too by a certain change of corpulency. 6 The active spawning season can be deduced to March and April. 7 The sudden decrease of ovary weight and the increase of the ovary of the minimum egg diameter appear at the end of the active spawning season. 8 In the past rich years of 1938~1938, the active spawning season might be January to April in Kyushu, February to June in the coast of the Japan Sea. / 昭和14年2月より4月までの3カ月間に,山口県仙崎において刺網による大羽マイワシの11魚群を連続的に採集し,主として雌魚の群成熟度と年令・体長・水温・肥満度との関係を検討した。1 群成熟度は,選択卵径平均法により各個体の卵巣の成熟度を0.2mm毎に7等分し,その各階級の組成によって魚群の成熟度を表現した。2 高年令ほど完熟し放卵する個体の出現率,成熟度が高い。3 体長が20cm以上の魚は完熟し放卵する個体が著しく多い。4 成熟度が0.2mm以下を示す出現率と完熟魚(1.0mm以上)の出現率の合計により,産卵度を表示する事が出来ると推定する。5 肥満度の変化によってもある程度産卵度を推定出来る。6 山口県沿岸の産卵時期は過去の豊漁時代も不漁時代も大差がないと推定する。即わち大よそ3月4月が産卵盛期である。7 終漁期には卵巣重量激減.最未熟魚増大が見られる。8 各海域・各月産の魚群(94魚群)の群成熟度を卵径平均値で比較すると,昭和11~14年頃の豊漁時代では,産卵盛期は九州で1月~4月,日本海で2月~6月であったと推定出来る。
URI: http://hdl.handle.net/10069/31867
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第8号

Citable URI : http://hdl.handle.net/10069/31867

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