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Summary

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results and discussion
  6. References

The relationships are presented between total length and wet weight and between total length and standard length for four species of righteye flounder from the south coast of Korea.


Introduction

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results and discussion
  6. References

Four species of righteye flounder, Pleuronichthys cornutus, Pseudopleuronectes yokohamae, Clidoderma asperrimum and Kareius bicoloratus are mainly distributed in the coastal waters of the East China Sea, Japan, and Korea, forming a relatively important economic and ecological fishery resource in the Korean coastal waters (Yamada et al., 1986; NFRDI (National Fisheries Research and Development Institute), 2004).

Length–weight relationship (LWR) and length–length relationship (LLR) parameters (a, b) have basic uses in the assessment of fish stocks and populations (Ricker, 1968; Ruiz-Campos et al., 2006). This paper provides LWRs and LLRs for the four aforementioned species of righteye flounder.

Materials and methods

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results and discussion
  6. References

Fish specimens were collected monthly between April 2009 and March 2011. The fishing grounds are located on the south coast of Korea, and fish were collected from depths between 10 and 50 m using a gill net and shrimp beam trawl. Fish were taken to the laboratory for measurement of total length (TL), standard length (SL), and wet weight to the nearest millimeter and gram, respectively. Sex was macroscopically determined by examining gonads.

For each species the weight–length function W = aLb was fitted to the data, where W is the wet weight in g, L is total length in cm, and a and b are parameters estimated using a simple linear regression analysis of log-transformed data. As extreme outliers attribute to data error, we removed outliers before fitting a linear regression (Froese et al., 2011). The 95% confidence intervals (CI) of the parameters and the statistical significance level of r2 were estimated using systat software (Systat version 12, SPSS Inc.). TL and SL relationships were established using linear regression analysis of TL = b SL. LWRs and LLRs were summarized over all months separately for males, females, and both sexes. Analysis of covariance (ancova) was used to determine significant differences in the slopes of length–weight regressions between males and females.

Results and discussion

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results and discussion
  6. References

Length–weight and length–length regressions were applied to a total of 1 174 specimens of the four species of righteye flounder. The estimated parameters of LWRs and LLRs, along with descriptive statistics by sex and species, are given in Tables 1 and 2.

Table 1. Parameters of length–weight regressions (LWRs) for four species of righteye flounder (Pleuronectidae) on the south coast of Korea, 2009–2011
SpeciesSexnLength (cm)Weight (g)W = aLb
MinMaxMinMax a 95% CI of a b 95% CI of b r 2
  1. F, female; M, male; A, all individuals; n, number of individuals; a, intercept; b, slope; r2, coefficient of determination; CI, confidence intervals.

Clidoderma asperrimum F6715.542.146.31067.20.0080.007–0.0093.1703.069–3.2250.978
M3516.531.256.7407.80.0080.004–0.0093.1653.018–3.3120.984
A10215.542.146.31067.20.0080.007–0.0103.1693.083–3.2440.989
Kareius bicoloratus F5717.065.052.13087.20.0190.013–0.0282.8572.740–2.9750.979
M4318.532.664.5333.50.0130.005–0.0322.9682.682–3.2530.942
A10117.065.052.13087.20.0180.013–0.0242.8732.779–2.9670.977
Pleuronichthys cornutus F34715.030.544.9368.80.0100.008–0.0113.1223.052–3.1910.945
M16214.827.038.1263.20.0100.008–0.0123.0973.006–3.1880.934
A50914.830.538.1368.80.0100.008–0.0123.1142.984–3.2440.943
Pseudopleuronectes yokohamae F23612.544.620.41183.70.0110.009–0.0143.0192.943–3.0940.964
M15913.541.928.61009.30.0130.010–0.0182.8872.877–3.0830.954
A39512.544.620.41183.70.0120.010–0.0143.0042.943–3.0650.960
Table 2. Parameters of length–length simple linear regressions (LLRs) for four species of righteye flounder (Pleuronectidae) from the south coast of Korea, 2009–20011
SpeciesSexnTL =  +  b SL
a b 95% CI of b r 2
  1. F, female; M, male; A, all individuals; n, number of individuals; a, intercept; b, slope; r2, coefficient of determination; CI, confidence intervals.

Clidoderma asperrimum F670.0240.8570.832–0.8820.986
M35−0.3140.8730.854–0.8920.996
A102−0.0570.8610.843–0.8790.989
Kareius bicoloratus F57−0.4490.8660.849–0.8820.995
M440.8060.8100.765–0.8550.969
A101−0.4280.8640.850–0.8770.944
Pseudopleuronectes yokohamae F2360.4070.8470.837–0.8560.992
M159−0.5660.8560.844–0.8690.991
A3950.4410.8490.842–0.8570.992
Pleuronichthys cornutus F347−0.4200.8250.810–0.8390.972
M162−0.1390.8090.787–0.8310.971
A509−0.3800.8220.811–0.8340.975

All LWRs were highly significant (P < 0.001), with r2 values >0.934. The r2 values ranged from 0.934 for male Pleuronichthys cornutus to 0.989 for Clidoderma asperrimum. The LLRs among the two length measurements were also highly correlated (r2 > 0.944, P < 0.001).

The regression slope b of the LWRs did not differ significantly between the sexes in the four species (ancova, P > 0.05). For all species presented in this paper, b values were generally in agreement with previous results for fishes in the same family obtained from other geographical areas (Wigley et al., 2003; Dulčić and Glamuzina, 2006; Orlov and Binohlan, 2009). Length–weight and length–length regressions for the four species studied here are also available in FishBase (Froese and Pauly, 2013). Almost all previous FishBase listings for these species represent sex-combined data without confidence intervals for a and b. In addition, some results were based on an insufficient number of samples for accurate representations of LWRs and LLRs. These problems preclude a direct comparison with the present study.

In conclusion, this study provides information on the LLRs and LWRs of four species of righteye flounder captured on the south coast of Korea. Our results should be useful for fishery biologists and managers in Korea.

References

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results and discussion
  6. References
  • Dulčić, J.; Glamuzina, B., 2006: Length–weight relationships for selected fish species from three eastern Adriatic estuarine systems (Croatia). J. Appl. Ichthyol. 22, 254256.
  • Froese, R.; Pauly, D., (Eds). 2013: FishBase. World Wide Web electronic publication. Available at: http://www.fishbase.org (accessed on 12 February 2013).
  • Froese, R.; Tsikliras, A. C.; Stergiou, K. I., 2011: Editorial note on weight–length relations of fishes. Acta Ichthyol. Piscator. 41, 261263.
  • NFRDI (National Fisheries Research and Development Institute), 2004: Commercial Fishes of the Coastal and Offshore Waters in Korea. Nat'l. Fish. Res. Dept. Ins., pp. 333. (in Korean).
  • Orlov, A.; Binohlan, C., 2009: Length–weight relationships of deep-sea fishes from the western Bering Sea. J. Appl. Ichthyol. 25, 223227.
  • Ricker, W. E., 1968: Methods for assessment of fish production in freshwaters. Blackwell Scientific Publications, Oxford, pp. 313.
  • Ruiz-Campos, G.; González-Acosta, A. F.; De La Cruz-Agüero, J., 2006: Length–weight and length–length relationships for some continental fishes of northwestern Baja California, Mexico. J. Appl. Ichthyol. 22, 314315.
  • Wigley, S.E.; McBride, H.M.; McHugh, N.L., 2003: Length–weight relationships for 74 fish species collected during NEFSC research vessel bottom trawl surveys, 1992–99. NOAA Technical Memorandum NMFS-NE-171.
  • Yamada, U.; Tagawa, M.; Kishida, S.; Honjo, K., 1986: Fishes of the East China Sea and the Yellow Sea. Seikai Regional Fisheries Research Laboratory, Nagasaki, pp. 501. (in Japanese).