Reproductive characteristics of Ishikari Bay [Japan] herring (Clupea pallasii Valenciennes)
2002
"Takayanagi, S. (Hokkaido. Central Fisheries Experiment Station, Yoichi (Japan)) | Ishida, R. "
"Localized Pacific herring, so called ""Ishikari Bay herring"" exists in waters off western and northern part of Hokkaido, Sea of Japan. Annual catches of herring spawners fluctuated for 1 to 14t in 1980-1996 and have sharply increased to 158-239 metric tons in 1997-2001. Present study is based on an investigation of specimens caught by gill net and Danish seine between November 1997 and April 2001 in Ishikari Bay and adjacent waters. Gonosomatic index and macroscopic ovary appearance suggested that Ishikari Bay herring spawn from early February to early May, mainly late February and March. Large-sized fish (over 27cm in fork-length) become to mature earlier than small-sized fish, so spawning herring caught in early fishing season were larger than those of the late season. Condition factor (CF) decreased in February and/or March at minimum level. There was positive correlation between egg size and fork-length of mature spawning herring. The relationship between fecundity (E) and fork-length (FL in cm) were shown with a regression of E=0.760 FL sup3.344 (r=0.939). These results are important for understanding stock fluctuation and conducting fisheries management."
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