• Fisheries and Aquatic Sciences
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• 제26권3호
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• pp.216-223
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• 2023

Pacific yellowtail emperor, Lethrinus atkinsoni Seale, 1910, is one of the most targeted reef fish species in Southern Sulawesi, Indonesia. Therefore, assessing its stock is important to understand the condition of the population, providing valuable inputs for sustainable fisheries management in the area. Here we assess the stock condition of L. atkinsoni in Southern Sulawesi, Indonesia, using the length-based spawning potential ratio model. A total of 4,887 individuals were collected from commercially small-scale fishers from January to October 2022. The total length, sex, and gonad maturity of the individuals were examined. We observed that the fish length ranged from 10.5 to 39.5 cm, with an average length of 23.3 cm. The sex ratio was equal (1:1.2) between male and female individuals. Length at first maturity and length at first capture were 23.4 and 19.6 cm, respectively. In addition, we observed a growth coefficient of 0.45/year, with an asymptotic length of 41.14 cm and natural mortality of 0.6/year. Based on these life history parameters, we observed the spawning potential ratio (SPR) value of 12%, indicating an unsustainable fishery level (SPR of < 30%). Further concerns related to the sustainability of the species and strategy to rebuild stock of the L. atkinsoni in Southern Sulawesi are of utmost importance.

• 한국수산과학회지
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• 제53권6호
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• pp.942-953
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• 2020

Achieving optimal sustainable yields (i.e., avoiding overfishing and maximizing fishery harvest at the same time) is one of the main objectives in fisheries management. Generally, management reference points (MRPs) such as fishing mortalities (Fmsy, F0.1, Fx%) have been suggested for the purpose. In this study, we intended to suggest MRPs for Korea chub mackerel Scomber japonicus stock, using a stochastic catch-at-age model (SCAA) and evaluate whether the current fishing intensity on the stock is appropriate. We used length frequency and catch-per-unit-effort data on the Korea chub mackerel stock collected from the large purse-seine fishery, and yields landed by all fisheries from years 2000 - 2019. We calculated yield per recruit and spawning potential ratio, and projected spawning stock biomass (SSB) under different fishing mortality, assuming annual recruitments were solely controlled by environmental effects (i.e., steepness of 1.0). Some of our major findings and suggestions were that the overfishing threshold would be F46%; i.e., the fishing mortality in the terminal year, 2019 was 0.257/year, which corresponded to F46%.

• Ocean and Polar Research
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• 제40권1호
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• pp.15-22
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• 2018

In the present study, we investigated temporal variation in the reproductive effort and biochemical contents in adult Manila clam Ruditapes philippinarum at Shi-Heung-Ri beach on the east coast of Jeju Island. Gonad-somatic index (GSI), a ratio of the egg mass to the total biomass determined using ELISA increased dramatically from late May to June (7.1% to 19.5%). In mid-July, GSI dropped to 15.1%, indicating spawning on a small scale during this period. GSI also declined dramatically from late August (15.5%) to September (4.3%), suggesting that massive spawning occurred during this period. A positive correlation was observed between clam size and potential fecundity, while potential fecundity ranged between 1.19-8.40 million eggs/clam. Total proteins and lipids in the tissue increased from late spring to mid-summer, coinciding with an increase in GSI. Protein, lipid and carbohydrate contents in the tissue were lowest in January, indicating that clams were suffering from poor nutritional circumstances, which may be associated with poor food supply from the environment. Monthly increase and/or decrease in the body weight were closely related to gonad maturation and subsequent spawning, which was also linked to temporal changes in the contents of protein, lipid and carbohydrates in the tissue.

• Fisheries and Aquatic Sciences
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• 제27권4호
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• pp.256-264
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• 2024

Small pelagic fish populations have long been exploited by various fishing gears in the Natuna Sea, and since the 1970s, purse seine exploitation has expanded to offshore fishing grounds. Various small pelagic fish species are exploited from these waters including spotted sardinella (Amblygaster sirm). This research was conducted for 22 months, from March 2019 to December 2020. The fish sample was taken from the purse seine fleet's catch in the fisheries management area (FMA) 711 Natuna Sea and Karimata Strait, which was brought to Pemangkat fishing port in the West Kalimantan Province, Indonesia. This paper aims to determine the exploitation status of spotted sardinella in the Natuna Sea as a recommendation material for management policies. The methods used in this analysis are estimated age, cohort, population parameters, and spawning potential ratio of spotted sardinella. The results show three primary cohorts of spotted sardinella in the Natuna Sea, with ages ranging from 9 months to 3.1 years and a maximum attainable age (longevity) of 4.3 years. The asymptotic value (L_∞) is 21.79 cmFL in length, with a growth rate (K) of 0.65 per year. The natural mortality rate (M) was 1.19, the total mortality rate (Z) was 2.19, and the fishing mortality rate (F) was 0.99. The exploitation rate (E) was 0.45 and the stock status was still in a sustainable condition. Therefore, the sardinella fisheries can be developed using a precautionary approach and focus on the ecosystem sustainability of FMA 711.

• 한국수산과학회지
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• 제34권4호
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• pp.355-358
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• 2001

본 논문은 한국 근해 다종어업 자원의 평가모델에 대한 연구결과로서 대형기선저인망쌍끌이어업과 같은 단일어업에 의하여 다종자원을 이용하는 형태이다. 단일어구에 의한 다종자원의 평가모델은 단일어구에 어획되는 다종자원 중 어획량비율이 상위를 차지하는 어종을 선별한 후 각 어종에 대한 혼획율 및 자원생태학적 특성치를 추정하여 Beverton and Holt (1957)의 가입당생산량 모델을 변형시킨 다종가입당 생산량모델을 이용하는 것이다. 이 모델은 현재의 $t_c$에서 다종에 대한$F_{0.1}$에 해 당하는 F값을 구하여 각 어종별 가입당산란자원량 모델에 적용하였으며, 이때의 산란자원량 수준인 $F_{x\%}$를 추정하여 자원평가에 이용하였다.

• 한국수산과학회지
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• 제49권6호
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• pp.785-791
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• 2016

Seasonal variation in the composition and fatty acid, amino acid, cholesterol, and vitamin contents in the muscles of the mandarin fish Siniperca scherzeri, caught in Soyangho Lake, Korea, was studied. The moisture content was 74.5-78.7 g/100 g, lipids ranged between 1.06 and 4.23 g/100 g, protein between 18.5-20.7 g/100 g, and ash between 0.74 and 2.04 g/100 g. The moisture content was lowest in May and tended to increase from June to October. The highest protein levels occurred in May, which coincided with the timing of oocyte maturation, and then decreased at the beginning of spawning. The highest lipid levels occurred in May and November coinciding with the periods before spawning and hibernation. The ratio of EAA/NEAA was higher than the value recommended by FAO for an 'ideal' food protein. There were significant differences in Mg and Fe contents with spawning; they were highest in May. Contents of vitamin A and E were from not detected (ND) to $17.1{\mu}g/100g$ and ND to 0.69 mg/100 g, respectively and were highest in November. The content of niacin tended to decrease in June and increased until November and hibernation. The cholesterol content was 14.9-78.9 mg/100 g; it decreased from March to July and then increased until November. In conclusion, there is potential for expanding the commercial utilization of the mandarin fish as a food resource.

• Fisheries and Aquatic Sciences
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• 제9권1호
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• pp.7-13
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• 2006

Using biochemical methods, we determined the potential of local female shrimp populations as breeding stock to select the best adult prawns for improving larval production. As condition indexes, we selected total RNA, DNA, their ratio, and trypsin activity. The DNA content in the pleopods of each local population was similar, i.e., between $0.90{\pm}0.06\;and\;1.02{\pm}0.04(SE){\mu}g/mg$. In comparison, the RNA contents differed markedly between $2.00{\pm}0.09$ and $0.96{\pm}0.08\;{\mu}g/mg$. Therefore, the RNA/DNA (R/D) ratio in the pleopod could be used as a condition index because it represents a biochemical characteristic of the population. The mean pleopodal R/D ratio of the Goheung population was the highest at $2.52{\pm}0.19$, which indicated the best condition. Trypsin activity was influenced little by shrimp condition and more by the amount of food ingested. The gonadosomatic index (GSI) and R/D ratio in the gonads provided offsetting information about the instantaneous gonad maturity. The Goheung population had the highest instantaneous GSI, despite some spawning. Based on the condition indexes and time of gonad maturation, the Goheung shrimp population is suitable for use as breeding stock.

• 한국패류학회지
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• 제15권1호
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• pp.31-39
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• 1999

본 연구는 1994년 6월부터 7월까지 광양만의 조화조간대와 덕산조간대에 서식하는 바지락(Ruditapes philippinarum: Bivalvia)의 개체군동태와 이차생산을 알아보기 위하여 수행되었다. 1994년 6월부터 1995년 4월까지 각장 빈도분포는 이중모드형을 보였으며, 이 후 단일모드형으로 변하였다. 중앙값은 시간에 따라 오른쪽으로 이동하였으며, 이는 각장의 성장을 의미한다. 평균서식밀도는 시간에 따라 감소하였다. Chohwa A에서 가장 서식밀도가 높았으며, Chohwa B, Toksan C, Toksan D의 순으로 감소하였다. 새로운 연령군의 가입은 상부조간대에서 먼저 일어나고, 이후 하부조간대로 이동하였다. 각 연령군의 육질부 생물량은 춘계의 산란기 직전까지 급격히 증가하다가 이후 서서히 감소하였다. 연평균생물량은 Chohwa A에서 170.7 g m$^{-2}$ , Chohwa B에서 220.7 g m$^{-2}$ , Toksan C에서 21.8 g m$^{-2}$ , 그리고 Toksan D에서 45.2 g m$^{-2}$ 를 기록하였다. 육질부 연간 생산량은 Chohwa A에서 259.72 g m$^{-2}$ yr$_{-1}$, Chohwa B에서 359.79 g m$^{-2}$ yr$_{-1}$, Toksan C에서 45.02 g m$^{-2}$ yr$_{-1}$, Toksan D에서 68.88 g m$^{-2}$ yr$_{-1}$를 기록하여 조화조간대의 연생산량이 덕산조간대보다 높았다. 반면에 P:B ratio는 덕산조간대가 1.70으로 조화조간대의 1.58보다 높았다. 즉 잠재적 먹이원의 총량이 많은 조화조간대에 바지락의 서식밀도, 생물량, 생산량이 많았으나, 단위개체당 이용가능한 먹이양과 공간의 관점에서 경쟁이 적은 덕산조간대가 개체의 성장과 P:B ratio가 양호하였다.