Fisheries science
Print ISSN : 0919-9268
Age and Growth of Pointhead Flounder Hippoglossoides pinetorum in Ishikari Bay, Hokkaido
Osamu TominagaKen InoguchiYasuhiro WatanabeMotohito YamaguchiToshikuni NakataniToyomi Takahashi
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1996 Volume 62 Issue 2 Pages 215-221


Pointhead flounder, Hippoglossides pinetorum, taken by commercial gillnets and an experimental beam trawl net in Ishikari Bay, Hokkaido from September 1991 to July 1993 were aged using polished otoliths (saggitae). Ages were validated by the monthly change in the percentageof otolith with translucent edge and marginal increments; a single opaque and translucent zone was formed annually. The regression method and Lee (Fraser-Lee)'s method were used to estimate the back-calculated length. Growth of pointhead flounder was expressed as Lt=251.9(1-exp-0.261(t-0.142)) formales and Lt=315.1(1-exp-0.219(t-0.200)) for females using back-calculated lengths by the regression method and Lt=251.6(1-exp-0.263(t-0.142)) for males and Lt=333.0(1-exp-0.204(t-0.186)) for females using back-calculated lengths by Lee's method, where Lt is the standard length (mm) at estimatedage t. Small differences in the theoretical lengths of older female fish were found between the twomethods. However, the theoretical standard lengths predicted by the two methods were very similar at most estimated ages and indicated the approximate actual length at each age.

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