Blackfin flounder
Research conducted in Korea on Pleuronectidae species includes studies of the ages and growths of
The present study analyzed data on the age and growth of
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Fish sampling and data collection
The
A pair of left/right otoliths was extracted and, after the removal of organic matters on the surface, they were dried and treated for easy observation by grinding close to the nucleus with sandpaper. Translucent and opaque zones appeared alternately in the otolith (Fig. 2A). Annuli were found at the boundary between opaque and translucent zones, and these were analyzed on a PC monitor (with the image analyzer package iSolution Lite, IMT i-Solutin Inc., Daejeon, Korea) connected to a dissecting microscope.
The otolith radius (R) was measured along the longest axis from the otolith center to the posterior margin, and the ring radius (rn) was measured in μm from the otolith center to each annulus (Fig. 2B).
To determine the period of annulus formation, the monthly variation in the marginal index (MI) was calculated by the following equation:
R is otolith radius and rn is the ring radius to the n-
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Relationships between TW-TL and TL-R
Relationship between TW and TL was estimated by TW=aTLb, where a and b are parameters. Relationship between TL and otolith radius (R) was estimated by linear regression analysis.
Growth in length of
Lt is the TL at age t, L∞ is the theoretical maximum length, K is the growth coefficient, and t0 is the theoretical age at length zero.
An analysis of covariance (ANCOVA) was used to compare weight-length relationships between sexes, and growth difference between males and females for each age was examined by
The total number of
Mean ring radius on the otolith of the Blackfin flounder Glyptocephalus stelleri in the East Sea
that females are longer than males (Fig. 3).
Monthly variation in MI was highest in July, low in August and September, showing an increasing trend from October (Fig. 4). The annuli of
The average ring radius from the otolith center to each annulus is shown in Table 1. It ranged from r1 = 1.152 ± 0.110 mm to r9 = 3.782 ± 0.340 mm in females and from r1 = 1.160 ± 0.106 mm to r7 = 3.180 ± 0.098 mm in males. The average ring radius female was apparently longer than for males, for each age group.
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Length-radius and weight-length relationship
Relationship between R and TL is shown in Fig. 5. There were significant differences in this relationship between males and females (ANCOVA,
Relationship between TW and TL is shown in Fig. 6. It was TW = 0.002TL3.392 (r2 = 0.970) for females and TW = 0.002TL3.335 (r2 = 0.961) for males.
The average TLs for each annulus were back-calculated from the for going relationship between R and TL based on the average ring radii to the annuli (Table 2). The estimated TLs of
Back-calculated total length at the formation of annuli in otolith of the Blackfin flounder Glyptocephalus stelleri in the East Sea
females were longer than those of males for all ages. The result of
The Von Bertalanffy growth functions of male and female
Lt = 39.71(1 - exp(-0.152(t+1.156))) for females; Lt = 32.16(1 - exp(-0.213(t+0.879))) for males (Fig. 7).
The age of
The growth structures of the left/right otoliths and the annulus mark formation position are different in some flounders such as
Our results indicate that annulus of
Comparison of age, total length and location of Glyptocephalus stelleri reported by different authors
during winter to spring. Ishida and Kitakata (1953) reported that otolith annuli form translucent zones from June to September, and that opaque zones are formed from March to May. Thus, the results of this study show differences in the formation of the annual mark.
The spawning period of
We found that annulus formation occurred around September, with the first annulus formation at age 1.4 which is about 4 months after spawning period. Similar results have been reported for other flounders such as
The growth of
There was no significant difference between males and females in the annual growth rate of
Geographic differences in the growth rates and longevities of