• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2000년도 춘계수산관련학회 공동학술대회발표요지집
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• pp.328-329
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• 2000

This research is to estimate population parameters of the Korean horse mackerel stock and to determine the status of the stock. Considering the linkage of recruitment with the variation of environmental conditions in the early life history, acceptable biological catch (ABC) of horse mackerel was estimated. (omitted)

• 수산해양기술연구
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• 제48권4호
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• pp.445-451
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• 2012

We developed an age-based spawner-recruit model incorporating environmental variables to forecast stock biomass and recruits of pelagic fish in this study. We applied the model to the Tsushima stock of jack mackerel, which is shared by Korea and Japan. The stock biomass of jack mackerel (Trachurus japonicus) around Korean waters ranged from 141 thousand metric tons (mt) and 728 thousand mt and recruits ranged from 27 thousand mt to 283 thousand mt. We hind-casted the stock biomass to evaluate the model performance and robustness for the period of 1987~2009. It was found that the model has been useful to forecast stock biomass and recruits for the period of the lifespan of fish species. The model is also capable of forecasting the long-term period, assuming a certain climatic regime.

• 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%.

• Fisheries and Aquatic Sciences
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• 제24권4호
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• pp.139-152
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• 2021

The main purpose of this study is to fit catch-per-unit-effort (CPUE) data about Korea chub mackerel (Scomber japonicus) stock with a state-space production (SSP) model, and to provide stock assessment results. We chose a surplus production model for the chub mackerel data, namely annual yield and CPUE. Then we employed a state-space layer for a production model to consider two sources of variability arising from unmodelled factors (process error) and noise in the data (observation error). We implemented the model via script software ADMB-RE because it reduces the computational cost of high-dimensional integration and provides Markov Chain Monte Carlo sampling, which is required for Bayesian approaches. To stabilize the numerical optimization, we considered prior distributions for model parameters. Applying the SSP model to data collected from commercial fisheries from 1999 to 2017, we estimated model parameters and management references, as well as uncertainties for the estimates. We also applied various production models and showed parameter estimates and goodness of fit statistics to compare the model performance. This study presents two significant findings. First, we concluded that the stock has been overexploited in terms of harvest rate from 1999 to 2017. Second, we suggest a SSP model for the smallest goodness of fit statistics among several production models, especially for fitting CPUE data with fluctuations.

• 수산해양기술연구
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• 제52권4호
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• pp.386-393
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• 2016

It is essential to provide good environment for juvenile fish to grow and spawn in order to keep reproduction mechanism of fisheries resources. However, harvesting juvenile fish deprives adult fish of the opportunity to reproduce, thereby changing self-regulating renewable resources into non-renewable ones and preventing sustainable harvesting as well as reducing fishers' income. We reviewed the catch status of Korea on juvenile mackerel and analyzed how reducing the catch ratio of juvenile mackerel may affect the spawning stock and Korean fishermen's revenue. In addition, we analyzed the problem of caching juvenile mackerel in Korean fisheries and current efforts to protect and reduce the catch ratio of juvenile mackerel in Korea. Furthermore, we suggested future efforts to protect juvenile mackerel. The result of the study showed that reducing the catch ratio of juvenile mackerel from 44.4% to 30.0% would increase fishers' revenue by 60.6 billion KRW. We suggest the changing of purse seine fishery's catching methods from night operation to day operation, relocation of fishing vessels to move to other fishing grounds when fishing vessels meet high density of juvenile mackerel, and consumers' clever choice of consuming adult mackerel in order to accelerate the move toward protecting juvenile mackerel in Korea.

• 자원ㆍ환경경제연구
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• 제19권4호
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• pp.771-804
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• 2010

본 논문은 이산바이오경제모형을 이용하여 자유입어와 단독소유상황 하에서 지속가능한 자원을 유지하고, 경제적 이윤 극대화를 달성할 수 있는 최적 생산량을 추정하였다. 특히, 본 연구에서는 로지스틱 성장함수, 콥-더글러스 생산함수, 수산물에 대한 비용 및 이윤함수들이 사용되었으며, 대형선망어업에서 주로 어획되는 고등어와 전갱이 자원이 분석대상으로 이용되었고, 관련 모형과 자료를 통하여 각 어종의 최적 생산과 어획노력을 분석하였다. 분석결과에 의하면 단독소유의 생태적 균형 하에서 대체적으로 고등어의 최적 생산량은 17만 2,512톤, 전갱이의 최적 생산량은 1만 6,937톤으로 추정되었다. 아울러 동일한 상황을 가정한 상태에서 최적 어획노력량의 경우 고등어는 8,508 양망횟수, 전갱이는 4,915 양망횟수로 추정되었다. 결론적으로 현행 대형선망어업보다 더 높은 순현재가치 창출을 위한 최적 관리(경영)는 어획노력량 수준을 다소 감소시켜 어업자원을 최적 수준으로 증가시켜야 한다는 것이다.

• 자원ㆍ환경경제연구
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• 제28권2호
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• pp.277-306
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• 2019

고등어는 국내에서 가장 많이 소비되는 어종 중 하나로 최근 기후변화, 해양 생태계 악화, 과잉 어획 등으로 인해 자원 고갈에 대한 우려가 커지고 있다. 본 연구에서는 이러한 고등어의 최적어획량, 자원량, 어획노력량 등을 최대 엔트로피 기법을 이용하여 추정하는 것을 목적으로 한다. 또한 부트스트래핑을 이용하여 최대 엔트로피 추정치의 통계적 유의성을 확인하고자 하였다. 분석 결과 고등어 자원량은 1990년대 중반 최대로 증가하였다가 2000년대 이후 점차 감소하는 것으로 나타났다. 또한 자원량 대비 어획량을 비교하면 1990년대 이전에는 28.5%, 1990년대 약 43.1%, 2000년 이후 36.3%로 추정되었다. 이는 1990년대 남획에 가까운 어획으로 고등어 자원량이 감소하였다가 정부의 수산 자원 관리 정책으로 인해 차츰 자원이 회복되었음을 의미한다. 그럼에도 불구하고 본고가 추정한 사회적 최적 자원량이나 최대지속가능어획량과 비교하면 현재 자원 스톡은 이 두 기준치를 달성하지 못해 현재보다 더 강화된 어획량 관리제도가 필요함이 확인된다.

• 한국수산과학회지
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• 제52권6호
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• pp.719-724
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• 2019

This study is an extension of our previous model for a size-based fish stock assessment. In the previous model, we applied an allometric length-weight relationship (W=α·L^β) to convert lengths of fish to weights, and estimated those parameters α and β, using data about lengths and weights aggregated over years. In this study, we focused on whether consideration of temporal (e.g., year-to-year) variability in those estimates (i.e., ${\hat{\alpha}}$ and ${\hat{\beta}}$) would contributive. After calculating year-specific estimates (i.e., year-specific pairs of ${\hat{\alpha}}$ and ${\hat{\beta}}$) by applying data about lengths and weights separated by year, we evaluated the contribution of those year-specific pairs of ${\hat{\alpha}}$ and ${\hat{\beta}}$ to the performance of the size-based stock assessment model. The model with such year-to-year variability being considered (lower AIC) outperformed that with the variability being ignored (higher AIC). We illustrated this study using data on Korean chub mackerel Scomber japonicus from 2005-2017.

• 한국수산과학회지
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• 제48권5호
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• pp.760-767
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• 2015

First annulus formation and age determination of otoliths were examined for chub mackerel Scomber japonicus collected in Korean waters over the one year from January to December in 2009. Translucent zone was regarded as an annual mark. Age interpretation criteria was based on the data of the number of translucent zone, capture date, and edge type of the otolith, assuming the nominal birthday to be 1 January. Monthly changes in mean marginal index indicated that translucent zone was formed once a year, mainly in June. The otolith of 0-ring group was detected comparing the progression by month of the smaller fish length, appearing to be a single first opaque zone. The average distance from the core to the first translucent zone was ~1.77 mm, provided as supplementary information to increase ageing accuracy. The ageing criteria for chub mackerel was made to determine correct year-class with the purpose of effective stock assessment. This method using nominal birthdate and edge type analysis could estimate age of fish closer to the true age than purely counting the number of translucent zone on a whole otolith.

• 한국수산과학회지
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• 제51권3호
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• pp.313-320
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• 2018

Chub mackerel Scomber japonicus is an economically important pelagic species in the western North Pacific. In the last 50 years, the annual total catch in Korean waters showed large fluctuations, ranging from 100 to $420{\times}10^3tons$. To provide a biological reference point for management of chub mackerel, we applied a simulation-based yield-per-recruit (Y/R) model that considered both temperature-dependent growth and size-dependent mortality. We estimated the fisheries yield with respect to varying biological reference points and environmental conditions, including 1) the instantaneous rate of fishing mortality (F), 2) length of fish at first capture ($L_c$), and 3) water temperature. The result of our analysis showed that the Y/R could be greatest when the $L_c$ ranges from 19-27 cm and F ranges from $1.48-2.00yr^{-1}$. Y/R increases with increased water temperature between 15 and $23^{\circ}C$. We suggest targeting an $L_c$ of 17 cm (age=0.6 years) under the assumed current of $F=0.48yr^{-1}$ for maximizing the chub mackerel harvest. Further analysis considering spawning and recruitment processes are required to provide biological reference points to ensure the sustainability of chub mackerel fisheries in Korean waters.