Life history characteristics of the protogynous parrotfish Calotomus japonicus from northwest Kyushu, Japan
Life history characteristics of the protogynous parrotfish Calotomus japonicus from northwest Kyushu, Japan
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DOI：
10.1007/s10228-009-0135-9
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发表时间：
2010-04-01
影响因子：
1.2
通讯作者：
Yamaguchi, Atsuko
中科院分区：
文献类型：
--
作者：
Kume, Gen;Kubo, Yoichiro;Yamaguchi, Atsuko
在这项研究中，我们研究了鹦嘴鱼Calotomus的生活史特征，使用2003年5月至2008年5月收集的个人在日本九州西北部的长崎半岛。使用天平进行年龄测定。边际生长量分析表明，生长轮每年7月左右形成。将两种性别的生长拟合为von Bertalanffy生长函数（L（a）= 513，k = 0.28，t（0）= 0.03，其中L（a）是理论渐近总长度（mm），k是生长速率系数，t（0）是零长度的理论时间）。观察到的男女最大年龄均为8岁。我们还根据性腺指数和性腺的组织学检查，这一物种的生殖生物学的特点。产卵季节从7月到10月，产卵活动高峰期在7月和8月。鱼在生命的第二年达到性成熟。雌性被认为是多产卵者，因为我们观察到卵巢中具有排卵后卵泡的样本，其中含有卵黄球卵母细胞或迁移核卵母细胞。所有雄性动物均具有次级睾丸，其特征为性腺壁中存在卵巢腔结构和精子窦。这表明，所有男性，无论他们是初始或终端阶段的男性，都经历了性转变。性别变化似乎发生在产卵季节，此后，变性的雄性能够在当前产卵季节的剩余时间内使雌性卵子受精。
In this study, we examined the life history characteristics of the parrotfish Calotomus japonicus, using individuals collected between May 2003 and May 2008 off the Nagasaki Peninsula in northwest Kyushu, Japan. Age determinations were performed using scales. Marginal increment analysis revealed that growth rings were formed annually around July. Growth in both sexes was fitted to the von Bertalanffy growth function (L (a) = 513, k = 0.28, t (0) = 0.03, where L (a) is the theoretical asymptotic total length in mm, k is the growth rate coefficient and t (0) is the theoretical time at zero length). Observed maximum age for both sexes was 8 years. We also characterized the reproductive biology of this species based on a gonadosomatic index and histological examinations of the gonads. The spawning season extends from July to October, with peak spawning activity occurring during July and August. Fish reach sexual maturity by the second year of life. Females are assumed to be multiple spawners, since we observed specimens with postovulatory follicles in ovaries containing either yolk globule oocytes or migratory nucleus oocytes. All males had secondary testes, which were characterized by the presence of an ovarian lumen structure and sperm sinuses in the gonadal wall. This indicates that all males, irrespective of whether they were initial or terminal phase males, had undergone a sexual transition. Sex change appears to occur during the spawning season, and thereafter sex-changed males are able to fertilize female eggs throughout the remainder of the current spawning season.