This study is aimed to compare stock assessment models depending on how the models fit to observed data. Process-error model, Observation-error model, and Bayesian state-space model for the Korean Western coast fisheries were applied for comparison. Analytical results show that there is the least error between the estimated CPUE and the observed CPUE with the Bayesian state-space model; consequently, results of the Bayesian state-space model are the most reliable. According to the Bayesian State-space model, potential yield of fishery resources in the West Sea of Korea is estimated to be 231,949 tons per year. However, the results show that the fishery resources of West Sea have been decreasing since 1967. In addition, the amounts of stock in 2013 are assessed to be only 36% of the stock biomass at MSY level. Therefore, policy efforts are needed to recover the fishery resources of West Sea of Korea.

This study is aimed to take a stock assessment of blackthroat seaperch Doederleinia seaperch regarding the fishing effort of large-powered Danish Seine Fishery and Southwest Sea Danish Seine Fishery. For the assessment, the state-space model was implemented and the standardized catch per unit effort (CPUE) of large powered Danish Seine Fishery and Southwest Sea Danish Seine Fishery which is necessary for the model was estimated with generalized linear model (GLM). The model was adequate for stock assessment because its r-square value was 0.99 and root mean square error (RMSE) value was 0.003. According to the model with 95% confidence interval, maximum sustainable yield (MSY) of Blackthroat seaperch is from 2,634 to 6,765 ton and carrying capacity (K) is between 33,180 and 62,820. Also, the catchability coefficient (q) is between 2.14E-06 and 3.95E-06 and intrinsic growth rate (r) is between 0.31 and 0.72.

This study researched the population of ecological characteristics of the goldeyes rockfish Sebasetes thompsoni sampled by gill net in the Ulleungdo area from February 2013 to February 2014 in order to assess the current stock status and provide scientific advice for management implementation. The instantaneous coefficient of total mortality (Z) was 0.78/year and the survival rate (S) was 0.459. The instantaneous coefficient of natural mortality (M) was 0.461/year. Based on the estimates of Z and M, the instantaneous coefficient of fishing mortality (F) was 0.318/year. The age at first capture (tc) was 4.41/years. Current Yield-per-recruit (YPR) was 30.83 g, and fishing mortality at maximum YPR (Fmax) and fishing mortality corresponding to 10% of the maximum slope in YPR curve (F0.1) were 3.257/year and 0.673/year, respectively. F35% and F40%, indicating fishing mortalities at 35% and 40% of maximum Spawning biomass-per-recruit (SBPR), were 0.619/year and 0.509/year, respectively. Based on the biological reference points, fishing mortality at overfished threshold yield (FOTY) was calculated as 0.509/year. Current SBPR/SBPRMSY was 1.313 above 1.0, which means ‘not overfishe,’ while current F/FOTY was 0.629 below 1.0, which indicates ‘not overfishing.’ In conclusion, the current status of goldeyes rockfish was located in green zone (i.e., not overfished and not overfishing) according to the revised Kobe plot.

This study was performed to estimate biomass and to provide management plan through population ecological characteristics, including survival rate, instantaneous coefficient of natural and fishing mortalities, and age at first capture of Flathead grey mullet, Mugil cephalus, in the coastal waters of Yeosu. Survival rate (S) of the flathead grey mullet was 3.671. The instantaneous coefficients of natural mortality (M) and fishing mortality (F) was estimated to be 0.325 /year, 0.962 /year for flathead grey mullet. Also fist capure age of flathead grey mullet was 3.61year. The current biomass of the flathead grey mullet in the study area was estimated to be 19.6 M/T and F0.1 and F40% were estimated 0.340 /year, 0.225 /year. For the stock assessment result, flathead grey mullet was not overfished but overfishing.

This study was performed to estimate biomass and provide management guidance through population ecological characteristics, including growth parameters, instantaneous coefficients of natural and fishing mortalities, and age at first capture of the starry flounder, Platichthys stellatus and olive flounder, Paralichthys olivaceus of Korea. For describing growth of this species, a von Bertalanffy growth model was adopted. The von Bertalanffy growth parameters estimated from a non-linear regression for starry flounder were L∞=48.25 cm, K=0.16/yr, and t0=-1.48, respectively and those for olive flounder were L∞=86.46 cm, K=0.26/yr, and t0=-0.29, respectively. Biomass of Platichthys stellatus was estimated by direct biomass estimation method was 2.6 M/T, that was estimated by indirect method was 13.4 M/Tt. Those of Paralichthys olivaceus were estimated as 10.1 M/T, 19.3 M/T, respectively. An yield per recruit analysis showed that the current yield per recruit on Platichthys stellatus was about 48.2 g with F=0.646/yr and the age at first capture (tc) 1.35yr, that on Paralichthys olivaceus was about 167.6 g with F=1.121/yr and the age at first capture (tc) 1yr.

This study was performed to assess the current stock condition of elkhorn sculpin along the Uljin area in the East Sea of Korea. To assess the state of the stock, yield-per-recruit (YPR) and spawning biomass-perrecruit (SBPR) analyses were performed. Estimates of Fmax and F0.1 were 2.10/year and 0.48/year, respectively, and those of F35% and F40% were 0.66/year and 0.54/year, respectively. Current fishing mortality was estimated at 0.63/year and the current age at first capture was 2.41years. F40% was set as the target reference point of the stock. SBPR at F40% and current SBPR were estimated to be 41.85g and 37.77g, respectively. Estimated FOTY which is the fishing mortality for the overfished threshold yield was 0.49/year. The ratio of SBPR/SBPRMSY was calculated as 0.90 and that of F/FOTY was 1.05. The ratio of tc/tc opt was calculated as 1.15 and that of F/FOTY was 1.17. Therefore, the current stock condition of elkhorn sculpin along the Uljin area of Korea has not been overfished, however, it indicates that a light overfishing is going on this stock.

Changes in ecosystem risks were evaluated using the ecosystem-based fisheries assessment (EBFA) approach of Zhang et al. (2009, 2010) and the comprehensive ecosystem-based fisheries management (EBFM) plan was made for the southern sea of Korea in this study. The risk assessment of the southern sea ecosystem was conducted by establishing ecosystem management objectives and by estimating risk scores (RS) for indicators. To conduct this analysis a number of indicators and their reference points for assessing these risk scores were developed in this study. The number of indicators in the risk analysis was 28 for the quantitative tier 1 analysis and 30 for the qualitative tier 2 analysis. The objective risk index (ORI), species risk index (SRI) and fisheries risk index (FRI) were calculated from the risk scores. Comparing the past (1988) and the current (2008) status of fisheries resources, management implications were discussed. The fishery risk index (FRI) of large purse seine fishery in the southern sea of Korea decreased substantially from 0.972 in 1988 to 0.883 in 2008, and improvement in the management of fisheries operated in the southern sea of Korea.

우리나라 연근해 해역에 대한 어족생물의 자원평가 및 그 관리를 위한 기초자료를 수집하기 위한 연구의 일환으로 동중국해를 대상으로 계량어군탐지기 및 트롤조업에 의해 수집된 어족생물의 음향학적 조사자료 및 수조실험자료 등을 종합적으로 분석하여 조사대상해역에 대한 어족생물의 어군반사강도를 추정한 결과를 요약하면 다음과 같다. 1. 1994년 4월에 제주도 남서방 해역에서 50kHz의 주파수에 대하여 측정한 트롤 예망층에 대한 어군의 평균체적산란강도(〈SV〉, dB)와 그 때의 트롤조업에 의해 어획한 단위체적당의 어획량(C, kg/m3)과의 사이에는 다음의 회귀직선식을 얻었다. = -32.4+10Log(C) 이 식에서 어획물 1kg당에 대한 어군의 평균반사강도의 추정치는 〈SV〉 = - 32.4dB/kg이었다. 2. 1989~1992년의 11월중에 동중국해에서 25kHz와 100kHz의 주파수에 대한 트롤 예망층의 평균체적산란강도(〈SV〉, dB)와 단위체적당의 어획량(C, kg/m3)과의 사이에는 다음의 회귀직선식을 얻었다. 25kHz : 〈SV〉 = - 29.8+10Log(C) 100kHz : 〈SV〉 = - 31.7+10Log(C) 이들 식에서 25kHz와 100kHz의 주파수에 대한 어획물 1kg당에 대한 어군의 평균반사강도의 추정치는 각각 -29.8dB/kg, -3.7dB/kg으로서, 25kHz에 대한 어군반사강도의 값이 100kHz에 대한 그 값보다 1.9dB 더 컸다. 3. 트롤조업에 의해 어획한 강달이, 말쥐치, 갈전갱이, 민태, 병어, 황돔, 민어, 고등어, 샛돔, 전갱이 등을 대상으로 25kHz와 100kHz의 주파수에서 측정한 어체의 평균반사강도와 체중과의 사이에는 다음의 회귀직선식을 얻었다. 25kHz : TS = - 34.0+10Log(W⅔) 100kHz : TS = - 37.8+10Log(W⅔) 이들 식에서 25 kHz와 100kHz의 주파수에 대한 어체의 1kg 당에 대한 평균반사강도의 측정치는 각각 -34.0dB/kg, -37.8dB/kg로서, 25kHz에 대한 어체의 평균반사강도의 값이 100kHz에 대한 그 값보다 3.8dB 더 컸다. 4. 제주도 근해에서 어획한 보구치의 부레의 등가반경(A)에 대한 체장(L)의 비솔(A/L)는 체장이 증감함에 따라 약간 감소하는 경향을 보였고, 그 평균치은 0.089이었다. 이상의 트롤조업 및 어탐조사, 또한 실험수조에서 측정한 어체의 반사강도를 종합적으로 고찰 할 때, 동중국해의 어업자원을 평가함에 있어 적용 할 수 있는 어군 1kg당에 대한 평균적인 반사강도는 25kHz와 100kHz의 주파수에 대하여 각각 -31.4dB/kg, -33.8dB/kg이라고 추정된다.

Yellow croacker, Tseudociaena manchurica Jordan et Thompson in the Yellow Sea and East China Sea are subjected to be caught by trawl nets throughout the year. First indices of population size in every period 8re calculated. Considering present status of the yellow croacker fishery and ecology of the fish, mathematical models must have been established in order to determine catchability coefficient, natural m ortali ty, fishing mortality, recrui ting coefficient of the fish ing ground, and dispersion coefficienl from the fishing ground. The results an, summmarized as follows: Catchabil i ty coefficient (C) = 2. 2628 × 10-5 Natural mortality (M)=0.3293 Population for lhe first half season(July 1st to the following January 3lst) Initial population = 14, 621 /MT Recruitment =45, 597 /MT Natural mortality = 8, 660 /MT Final population =42, 970 /MT Population for the latter 1131f scason(February 1st to June 30th) Initial population = 69, 170 /MT Dispersion =51, 688 /MT Natural mortality = 6, 082 /MT Final population = 1, 802 /MT.