• Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.350-353
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• 2010

This study demonstrated that cryopreserved semen from dead fish can be used for seedling production. Yellow croakers, Larimichthys polyactis, were killed and stored at temperatures of $20^{\circ}C$ or $0^{\circ}C$ for 6 hours. At 2 hour intervals, semen from these fish was collected using abdominal pressure and evaluated for spermatozoa motility and semen cryopreservation. Semen collected after 6 hours from dead fish stored at $0^{\circ}C$ could be cryopreserved and attained fertilization and hatching rates of $15.0{\pm}1.2%$ and $14.8{\pm}1.6%$, respectively. This study suggests that germ cells such as the semen of dead fish can be cryopreserved and utilized in the restoration of a species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.50-56
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• 2020

Determination of the precise size at sexual maturity is very important for science-based stock assessment and fisheries resource management. In this study, two different models, (1) a visual method and (2) a gonadosomatic index (GSI) method, were employed to estimate length at sexual maturity of the small yellow croaker Larimichthys polyactis in the Yellow Sea of Korea. The visual method is a common qualitative method using visual gonadal identification. Conversely, the GSI method is a quantitative method using the GSI, which can be easily and precisely collected. We compared results from these methods to determine the best approach, and to examine the practicality of the GSI method. Logistic regression of the maturity ogive was conducted using a general linear model (GLM) with the R statistics program. Also, the bootstrapped 95% confidence intervals of all estimates were calculated. The best-fit model was the visual method (R_Mc²=0.805, AUC=0.989, L₅₀=15.1). Among models using the GSI method, the model computing GSI_ref=0.94 was the best-fit model (R_Mc²=0.792, AUC=0.989, L₅₀=15.2). There was no significant difference between the two models, evidencing the effectiveness and accuracy of the GSI method.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.6
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• pp.413-424
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• 2005

The study focused on the fluctuation of the fisheries conditions in fishing ground of yellow croaker, Pseudosciaena polyactis Bleeker. A long-term decreasing trend was observed in the accumulated catches of the species since 1926, with increasing-decreasing fluctuation repeating 6 times. Periodicity was observed in 10-year interval in good fishing years, but not in poor fishing years which had irregular fluctuations. From the geographical distribution of the past catch per unit effort, it was presumed that a group of the species seasonally migrated but most of the groups stayed throughout year in the western area off Cheju Island, which was different from the assumptions of the 1970's. The fishing grounds were distributed along the migration route differently by season, throughout the Yellow Sea and the East China Sea, but shifted gradually southward and narrowed down to the area of $32^{\circ}N-125^{\circ}E$ off Cheju Island, where the center of fishing grounds was given birth to throughout the year with a relatively high density from autumn to spring. It was noted that a negative correlation was shown between the area of fishing grounds and density distribution of catch.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.613-619
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• 1994

To investigate the population differences of small yellow croaker (Pseudosciaena polyactis BLEEKER) in the Yellow Sea, five catching sites (three from China; Zoushan, Shanghai and Qingdao, two from Korea; Inchon and Mokpo) were selected for sampling. The populations of small yellow croaker from all five catching sites were investigated to analyze their mtDNA's restriction fragment length polymorphism (RFLP) using 18 kinds of restriction enzymes. The average molecular size of the entire mtDNA was estimated at $16.9{\pm}0.6\;kb$. According to the results of RFLP analysis, a total of 40 restriction sites were identified in every population surveyed and the overall cleavage patterns of mtDNA, based on the RFLP, showed similar tendencies. However, the five restriction enzymes such as ApaI, EcoRI, PstI, SmaI and SstII showed slightly different cleavage patterns which could have resulted from individual variations between the populations of Korea and China.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.29-36
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• 1992

This paper deals with the estimation of population ecological parameters, including growth parameters, survival rates, instantaneous coefficient of natural mortality and age at first capture, of the small yellow-croaker, Pseudosciaena Polyactis in Korean waters, which determine fluctuations in stock abundance. For describing the growth of the small yellow croaker, von Bertalanffy growth equation was recommended for the purpose of stock assessment, although the Gompertz model yielded the closest fit. The survival rate (S) of the croaker was estimated to be 0.219 (variance=0.0000262), and the instantaneous coefficient of natural mortality (M) was 0.4 $year^{-1}$. From the estimates of S and M, the instantaneous coefficient of fishing mortality (F) was calculated to be 1.11$year^{-1}$ implying an impact from fishing three times that of natural mortality. Finally, the age at first capture $(t_{c})$ was estimated to be 0.602.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.62-67
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• 2006

The maintenance of continuity on food processing has created a need for the rapid reinstatement of many types of frozen fish to an ambient temperature and good condition. A number of thawing methods are in current use have also several disadvantages in thawing time. discoloration mass loss caused by drying, capital and running cost. These damages are, it is claimed, either eliminated or improves by the vacuum system. An experimental study on the thawing for hair tail and Yellow croaker by the vacuum system were carried out. The Yellow croaker thawing time with this vacuum system took out 170 minutes to reach from $-10.3^{\circ}C\;to\;-0.8^{\circ}C$ at 20mmHg abs. and hair tail thawing time 220 minutes to reach from $-12.2^{\circ}C\;to\;0^{\circ}C$ at 20mmHg abs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.3
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• pp.199-206
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• 2005

As the basic study about improvement of yellow croaker drift gill net fishing implement and development of the fishing system, this study drew problem after synthetically analyzing hauling system of yellow croaker drift gill net used in the coast of Chuja Island and tested several characters and analyzed in hauling process with 5 step net hauler model for improving the problem. The analysis results are as follows. When the angle between axises of drum centers was small, it showed the tendency that hauling time was fast. Hauling time was faster when drum was 5 step rather than 3 step. When drum was 5 step, slippery phenomenon was small and hauling was stable. Tension was larger when drum was 5 step rather than 3 step. When drum was 5 step, the range of change of the maximum and minimum value was small and hauling was stable. When drum was 3 step, there was following formula between hauling time ($Ht_3$) and angle between axises of drum centers ($A_g$) $Ht_3$ : ($7.15Hs^{-0.81}$) $A_g^{-0.81}$, when drum was 5 step there was following formula.$Ht_5$ : ($6.45Hs^{-0.75}$) $A_g0.10$, here, Hs is hauling speed. When drum was 3 step and hauling speed was 28cm/sec, tension was $T=0.08A_8^3-1.60A_g^3-0.49A_g+369.56(r=0.99)$, when drum was 5 step, tension was, $T=-0.01A_g^3+1.96A_g^2-34.05A_g+414.58$ (r-0.99), here, T was tension(g).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.3
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• pp.220-231
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• 2016

Yield-per-recruit (YPR) analysis is used to provide management guidance for the efficient use of a fish cohort. However, the individual fish price per unit weight of small yellow croaker (Larimichthys polyactis) or hairtail (Trichiurus lepturus) increases dramatically by size in Korea. Therefore, age-based production value-per-recruit (PPR) analysis has recently been developed (Zhang et al., 2014). Since age determination requires a substantial amount of money and time and it is even impossible for some fish species, it is difficult to obtain age information to apply the age-based PPR model. Thus, we attempted to develop an alternative method, which uses length data rather than age information, called the length-based PPR analysis. The results revealed that length-based PPR analysis was much more conservative for stock management than the YPR analysis. Furthermore, the PPR analysis was more economically beneficial than the YPR analysis, which can prevent the fish stock from the economic overfishing. In conclusion, the length-based PPR analysis could be a proper approach for stock assessment in the case that the individual fish price per unit weight increases dramatically by size, and this analysis is useful to obtain vital management parameters under data-deficient situation when traditional stock assessment methods are not applicable.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.441-448
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• 2010

This paper was concentrated on the distribution and the composition of lost fishing gear on the sea bed around yellow croaker fishing ground in the near sea of Jeju, Korea from April to October 2009 in order to improve the fishery environment. Recovering lost fishing gears was carried out total 10 times with a trawlnet along the isobath. As the result, it seems reasonable to conclude that the amount of lost fishing gear has a deep connection with the dip of the sea bed as well as the fishing gear scale, fishing ground and so on. The amount of recovered lost fishing gears were in order of gillnets, dragged gears, traps and ropes. In particular, traps were recovered almost every time within the survey area.

• Journal of Aquaculture
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• v.22 no.1
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• pp.5-10
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• 2009

Spermatogenesis in male yellow croaker Larimichthys polyactis was histologically investigated by sampling testicular tissue from $2{\sim}3$ years old wild fishes captured from the coast of Mok-Po, South Korea. Spermatogenesis was characterized histologically, and staged according to the most advanced type of germ cell present. Annual reproductive cycle was classified into the following successive 4 stages: spermatogonia from August to September (rest stage), spermatogonia and spermatocytes from October to December (growth stage), spermatogonia, spermatocytes and spermatids from January to February (maturation stage), spermatogonia, spermatocytes, spermatids and spermatozoa from March to May (spermiation stage IV), and regressing testis from June to July (degeneration stage).