• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.448-453
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• 2015

This study was performed to estimate biomass and to provide management plan through population ecological characteristics, including survival rate, instantaneous coefficient of natural and fishing mortalities, and age at first capture of Flathead grey mullet, Mugil cephalus, in the coastal waters of Yeosu. Survival rate (S) of the flathead grey mullet was 3.671. The instantaneous coefficients of natural mortality (M) and fishing mortality (F) was estimated to be 0.325/year, 0.962/year for flathead grey mullet. Also fist capure age of flathead grey mullet was 3.61year. The current biomass of the flathead grey mullet in the study area was estimated to be 19.6 M/T and $F_{0.1}$ and $F_{40%}$ were estimated 0.340/year, 0.225/year. For the stock assessment result, flathead grey mullet was not overfished but overfishing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.203-213
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• 2011

The age and growth of flathead grey mullet, Mugil cephalus, were studied using samples collected from the coastal water of Yeosu from September 2009 to August 2010. Spawning season estimated from the gonadosometic index (GSI) was from November to January. A method for increasing the readability of the otolith was described and criteria for the interpretation of otolith was provided. The annual ring was formed in September once a year. Annual ring in otolith for flathead grey mullet is validated for fish aged 1-8 using the marginal increment analysis. Using the sectioned otolith, between reader precision was 84%. Also, Within-reader agreement for sectioned otolith age readings was higher (reader 1=84%, reader 2=87%). The relationship between fork length and total weight was TW=$0.022FL^{2.818}$. The estimated von Bertalanffy growth parameters for the flathead grey mullet were $L_{\infty}$=67.97cm K=0.164/year and $t_o$=-0.81year.

• Journal of fish pathology
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• v.36 no.2
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• pp.403-408
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• 2023

Mullet is an important marine aquaculture fish species in Korea, with a total of 7,237 tons produced as of 2022, making it the 5th most produced marine aquaculture fish species. In this study, ectoparasites presumed to be isopods were discovered in the fins of farmed flathead grey mullet (average weight 550 g), and the characteristics of the parasites were confirmed. The length of the parasite was 5 to 18 mm, and 3 to 7 parasites were infected per fish. To analyze the characteristics of the parasites, molecular biological identification and phylogenetic analysis were performed using the cytochrome c oxidase subunit I (COI) gene, and it was confirmed to be most closely related to Nerocila japonica in the Cymothoidae family. To confirm the parasite control effect, a direct exposure drug sensitivity test was conducted on five types of aquatic drugs and fresh water, trichlorfon was confirmed to be effective.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.194-201
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• 2014

Age and growth of flathead grey mullet Mugil cephalus were estimated using samples collected by a two-side fyke net in the coastal water off Taean in 2008. Age was determined by examination of annuli in otoliths and total lengths at ages were back-calculated from otolth-body size relationship. Total length ranged from 239 to 605 mm and mainly between 400 and 550 mm. Observed ages ranged from 1 to 7 years old and mainly between 3 and 5 years old. Total length (L, mm) was linearly related to otolith radius (R, mm); L=15.3+87.9 R. Total lengths at the annulus formation in otolith were back-calculated by Frazer-Lee method. Estimated length at the age 1 was $316{\pm}40.6mm$ ($mean{\pm}SD$) showing a fast growth rate during the early growth stage. Total length at each age (t) showed a wide range indicating the big difference in growth rate among individuals. Growth in total length can be expressed by a Von Bertalanffy growth curve as $L_t=542[1-{\exp}\{-0.493 (t+0.769)\}]$.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.185-195
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• 2020

Background: The flathead grey mullet Mugil cephalus has the widest distribution among mugilid species. Recent studies based on mitochondrial DNA sequences showed that the species comprises at least 14 different groups, three of which occur in the northwest Pacific. We analyzed the otolith microchemistry of M. cephalus at several locations in Korea to improve understanding of migration pattern and population origin. Results: We collected 123 sagittal otoliths from seven locations and determined their concentrations of eight elements (⁷Li, ²⁴Mg, ⁵⁵Mn, ⁵⁷Fe, ⁶⁰Ni, ⁶³Cu, ⁸⁸Sr, and ¹³⁸Ba) using laser ablation inductively coupled plasma mass spectrometry. Mean otolith elemental ratios differed significantly among the locations. The Sr:Ca, Fe:Ca, and Ba:Ca ratios were significantly higher than others, and useful chemical signatures for investigating the habitat use of M. cephalus populations. We identified five diverse and complicated migration patterns using the otolith data that we collected: estuarine resident (type I), freshwater migrant (type II), estuarine migrant (type III), seawater resident (type IV), and seawater migrant (type V). A canonical discriminant analysis plot revealed separation of two groups (type II in the Yellow Sea vs. other types in remaining locations). Two locations on Jeju Island, despite their close proximity, had fish with quite different migration patterns, corroborating previous molecular studies that distinguished two groups of fishes. Conclusion: We successfully showed that the migration patterns of the Korean mullet varied by location. Only fish from the western sector of Jeju had a unique migration pattern, which is likely confined population in this area. Among the eight otolith elements measured, the Sr:Ca ratio was found to be the best indicator of migration pattern and population origin.