Life history characteristics of the protogynous parrotfish Calotomus japonicus from northwest Kyushu, Japan

Abstract

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 ? = 513, k = 0.28, t 0 = 0.03, where L ? 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.

Comparisons of body sizes at sexual maturity and at sex change in the parrotfishes of Hawaii: input needed for management regulations and stock assessments

“…A monandric Kyushu population of C . japonicus was studied by Kume et al (). Patterns of sex allocation among multiple populations of C .…”

“…Kusen & Nakazono (1991) studied a monandric population of a congener [Japanese parrotfish Calotomus japonicus (Valenciennes 1840)] at Kagoshima Prefecture, Japan, in which all males were sex-changed TP fish. A monandric Kyushu population of C. japonicus was studied by Kume et al (2010). Patterns of sex allocation among multiple populations of C. carolinus and C. japonicus thus indicate that both species are effectively monandric, with all or most males being sex-changed secondary males.…”

Spawning season and size at sexual maturity of Kyphosus bigibbus (Kyphosidae) from northwest Kyushu, Japan

“…Detailed information on the study site can be found in Kume et al (2009). In the laboratory, fork length (FL, mm) and gonad weight (GW, 0.1 g) were recorded for each specimen.…”

High Arachidonic Acid Levels in the Tissues of Herbivorous Fish Species (Siganus fuscescens, Calotomus japonicus and Kyphosus bigibbus)

“…The comparatively high levels of both n-3 and n-6 PUFA in polar lipids in this study suggest that n-6 PUFA is the important membrane component of these three herbivorous species. High levels of ARA have also been observed in many gonadal fish lipids [54,64]. Moreover, ARA might also be an essential fatty acid for marine fish as well as n-3 HUFA due to their important role as the main eicosanoid precursor [65][66][67], which related to many physiological function, such as growth and survival [66], reproduction [68,69], and environmental stress resistance [70] in various larval and juvenile marine fish species.…”