Growth pattern of flathead flounder Hippoglossoides dubius in Funka Bay, Hokkaido, Japan

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The growth trajectories of flathead flounder Hippoglossoides dubius of the 1989, 1991, and 1995 dominant year-classes in Funka Bay, Hokkaido, Japan were investigated using otter trawl samples collected from 1990 to 2006. The von Bertalanffy growth model and linear equations showed good fit for the year-classes for both sexes. The observed linear increase in body length at ≥3 years old may be sustained by the dietary shift from ophiuroids and small crustaceans with low energy content to fish and decapods with high energy content. The total lengths estimated by back-calculation from the otolith increment radii obtained from older individuals were smaller than those estimated from age-length data at catch. This discrepancy is likely due to a seasonal difference in growth between body length and otoliths in H. dubius in Funka Bay, and/or to the high fishing intensity by bottom gill nets and the fact that fast-growing individuals tend to be caught at an earlier age.