National Research Institute of Far Seas Fisheries, Fisheries Research Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan.
J Fish Biol. 2010 Oct;77(6):1325-42. doi: 10.1111/j.1095-8649.2010.02752.x. Epub 2010 Oct 1.
Variations in otolith patterns, sizes and body morphometrics of jack mackerel Trachurus japonicus juveniles were investigated. Under transmitted light, translucent (W(t)) and opaque otoliths (W(o)) were detected in juveniles collected from Wakasa Bay between July 2005 and April 2006, whereas only opaque otoliths (G(o)) were detected in Goto-nada Sea individuals between May and June 2006. Three groups of juveniles were distinguished based on differences in hatch season, otolith size and growth history, and body morphometrics. As T. japonicus has different spawning seasons according to spawning grounds, each group was estimated to hatch in different waters. Juveniles with W(t) otoliths were considered to have stayed in coastal habitat longer, as the hatch area was estimated to be near Wakasa Bay. Juveniles with W(o) and G(o) otoliths appear to recruit to coastal waters at larger size, since their hatch areas were estimated to be far from each collection area. Larger otoliths of W(t) were attributed to otolith accretion after the second growth flexion, which was observed only for W(t) . Standard length of W(t) fish at the second otolith growth flexion was estimated to correspond to recruitment size to coastal rocky reefs in Wakasa Bay. Body morphometrics were correlated with otolith size after removing body size effect, suggesting that morphological variations of T. japonicus juveniles were also associated with the timing of recruitment to coastal habitat.
研究了日本马鲛幼鱼耳石形态、大小和体形体态的变化。2005 年 7 月至 2006 年 4 月期间，在若狭湾采集的幼鱼在透射光下检测到透明（W(t)）和不透明耳石（W(o)），而 2006 年 5 月至 6 月期间在五岛滩采集的个体只检测到不透明耳石（G(o)）。根据孵化季节、耳石大小和生长历史以及体形体态的差异，将三组幼鱼区分开来。由于日本马鲛根据产卵场有不同的产卵季节，估计每组在不同的水域孵化。具有 W(t)耳石的幼鱼被认为在沿海栖息地停留时间更长，因为孵化区估计在若狭湾附近。具有 W(o)和 G(o)耳石的幼鱼似乎在更大的体型时进入沿海水域，因为它们的孵化区估计远离每个采集区。较大的 W(t)耳石归因于第二次生长弯曲后的耳石积累，仅在 W(t)中观察到。W(t)鱼在第二次耳石生长弯曲时的标准长度估计对应于进入若狭湾沿海岩石礁的招募规模。在去除体型大小的影响后，体形体态与耳石大小相关，这表明日本马鲛幼鱼的形态变化也与进入沿海栖息地的时间有关。
