This study analyzes the comparative value chains of domestically caught coastal mackerel and Norwegian mackerel within the Korean market, across six stages: global supply and demand, domestic production and imports from Norway, distribution of raw mackerel, processing into semi-processed or final products, distribution of final products, and consumption. The research methodology combined qualitative and quantitative approaches, including in-depth interviews with 32 industry stakeholders (from fishing companies to government agencies) and an online survey of 400 Seoul consumers, utilizing conjoint analysis. Norway maintains market dominance through a demand-driven value chain, characterized by quality-focused production, efficient overseas processing networks in Southeast Asia and China, and aggressive marketing by the Norwegian Seafood Council. In contrast, Korea's coastal mackerel industry follows a supplier-driven value chain, facing challenges such as inconsistent quality due to year-round non-selective fishing, limited processing capabilities due to high labor costs and aging workforce, and lack of direct consumer marketing channels. The study identifies structural differences in the Korean market's value chain and suggests strategic improvements for the domestic mackerel industry while highlighting the need for a shift toward a more demand-oriented approach.

This study examines the price elasticity of demand for mackerel in the Busan Cooperative Fish Market, the largest wholesale fish market in South Korea. Using a two-stage least squares (2SLS) approach, the analysis addresses endogeneity in pricing by incorporating exogenous environmental variables, such as sea surface temperature (SST) and wind speed. The study estimates demand elasticity for three size categories of mackerel-large, medium, and small-and reveals significant differences across these categories. Large-size mackerel exhibits inelastic demand (-0.875), reflecting its status as a staple product with relatively stable consumer demand. Medium-size mackerel shows highly elastic demand (-2.450), likely due to its role as a substitute for both large and small mackerel. Small-size mackerel also demonstrates high elasticity (-3.444), attributed to its primary use in feed and processing, where demand is particularly sensitive to price changes. Diagnostic tests confirm the validity and relevance of the instrumental variables, with SST and wind speed strongly correlated with price but uncorrelated with consumer demand. These findings highlight the critical role of size-specific market characteristics in shaping price elasticity and provide valuable insights for policymakers and industry stakeholders to better manage mackerel supply and ensure pricing stability.

This study aimed to identify the selectivity of catches according to mesh size of gillnets, and to collect basic data for fisheries resource management plans for gillnets. The mesh selectivity test was conducted with five different mesh sizes (60, 66, 69, 75, and 96 mm) gillnet in coastal sea of Mukho port and the selectivity was analyzed using the Kitahara method. In results of the selectivity test, a total of 143 (36,249 g) of atka mackerel were caught and the 60 mm gillnet was the highest at 83 (18,596 g), which is about 58.0% of the total catch. The relative growth equation between body length and weight showed that weight tends to increase proportional to body length. The maximum length/mesh size value was showed 0.490 by the master curve of selectivity, and the 50% selection range was showed 0.138. Therefore, it was found that the size of the caught fish increased proportional to the mesh size. The results of this study were intended to be used as data for establishing a plan for efficient management of atka mackerel resources.

Recently, domestic fishing production of Japanese horse mackerel has been continuously decreasing. To achieve sustainable fishing of this species, it is essential to acquire its target strength (TS) for accurate biomass estimation and to study its ecological characteristics. To date, there has been no TS research using a broadband echosounder targeting Japanese horse mackerel. In this study, for the first time, we synchronized an underwater camera with a broadband frequency (nominal center frequency of 200 kHz, range: 160-260 kHz) to measure the TS according to the body size (16.8-35.5 cm) and swimming angle of the species. The relationship between Japanese horse mackerel length and body weight showed a general tendency for body weight to increase as length increased. The pattern of the frequency spectra (average values) by body length exhibited a similar trend regardless of body length, with no significant fluctuations in frequency observed. The lowest TS value was observed at 243 kHz while the highest TS values were recorded at 180 and 257.5 kHz. The frequency spectra for the swimming angles appeared to be flat at angles of –5, 0, 30, 60, 75, and 80° while detecting more general trends of frequency spectra for swimming angle proved challenging. The results of this study can serve as fundamental data for Japanese horse mackerel biomass estimation and ecological research.

In September and October 2020, combined acoustic and trawl surveys were conducted in the northwestern sea of Jeju Island. In the survey area, a region, so called Jeju region, was designated to esimate the biomass of chub mackerel and jack mackerel using a trawl survey method and frequency difference method. In the September survey, the weight ratios of jack mackerel and chub mackerel to the total catch were 24.6% and 2.8%, respectively, and in the October survey, those ratios were 24.9% and 20.7%, which were used to calculate their biomass (trawl survey). Using the frequency difference range (–8 to –3dB) corresponding to two species in 120 and 200 kHz, their biomass was estimated (frequency difference method). As a result, the biomass of two species from the trawl method was 3252.3 tons in September and 5777.0 tons in October. The estimated biomass by the frequency difference method was 4926.6 tons in September and 7521.5 tons in October. It was the first trial to estimate the biomass of two species using the trawl and frequency differencing methods in South Korea although there were some differences between two methods. In addition, horizontal distributions of acoustic backscattering strength over the entire survey area were mapped.

In this study, Target strength for multi-frequency (38 kHz, 70 kHz, 120 kHz and 200 kHz) of chub mackerel (Scomber japonicus) was estimated using by the KRM model. The body shape of the Chub mackerel was described by an X-ray system and the body length of 20 individuals ranged from 16 cm to 28 cm. The swimbladder tilt angle ranged between – 8 and – 14°, the maximum TS value according to the swimming angle of chub mackerel was – 33.0 dB at – 11°. The averaged TScm according to fork length was – 66.02 dB at 38 kHz, – 66.50 dB at 70 kHz, – 66.00 dB at 120 kHz and – 67.35 dB at 200kHz, respectively.

The purpose of this study is to compare short-term price predictive power among ARMA ARMAX and VAR forecasting models based on the MDM test using monthly consumer price data of frozen mackerel. This study also aims to help policymakers and economic actors make reasonable choices in the market on monthly consumer price of frozen mackerel. To analyze this study, the frozen wholesale prices and new consumer prices were used as variables while the price time series data were used from December 2013 to July 2021. Through the unit root test, it was confirmed that the time series variables employed in the models were stable while the level variables were used for analysis. As a result of conducting information standards and Granger causality tests, it was found that the wholesale prices and fresh consumer prices from the previous month have affected the frozen consumer prices. Then, the model with the highest predictive power was selected by RMSE, RMSPE, MAE, MAPE, and Theil’s inequality coefficient criteria where the predictive power was compared by the MDM test in order to examine which model is superior. As a result of the analysis, ARMAX(1,1) with the frozen wholesale, ARMAX(1,1) with the fresh consumer model and VAR model were selected. Through the five criteria and MDM tests, the VAR model was selected as the superior model in predicting the monthly consumer price of frozen mackerel.

Diet composition and trophic level of Trachurus japonicus were studied using 417 specimens collected by trawls, set nets and purse seine fisheries from March 2019 to February 2020 in the South Sea of Korea. The size of T. Japonicus ranged from 7.0 to 49.8 cm in total length. T. japonicus were a carnivore that fed mainly on euphausiids and pisces. In eddition, T. japonicus fed on small quantities of cephalopods, crabs etc. T. japonicus showed ontogenetic changes in feeding habits. The proportion of euphausiids decreased inversely proportional to body size whereas the consumption of pisces gradually increased. As body size of T. japonicus increased the mean number of prey per stomach and the mean weight of prey per stomach tended to increase, but the mean number of prey per stomach was not significantly different. As a result of the feeding strategy analysis, T. japonicus were specialized feeders with pisces and euphausiids as their dominant prey. The trophic level ranged between 3.57 ± 0.54 and 3.91 ± 0.65, and increased asymptotically with size of specimens. The average trophic level of the T. japonicus was 3.79 ± 0.61.

In this study, spray-dried double emulsion loaded bromelain was applied to Japanese Spanish mackerel fillets to develop fish-type, elderly-friendly foods. Japanese Spanish mackerel, treated with spray-dried double emulsions, were stored at 4oC for 24 h. For the characterization of emulsion particles, the particle size, ζ-potential, and morphology were determined. The color, TBARS, VBN, TMA, hardness, and adhesiveness of fish fillets treated by emulsion were measured for physicochemical properties. All the particle sizes of spray-dried emulsion were decreased while their double emulsion structure was maintained. Spray-dried emulsion reduced the color difference of fish fillets and did not catalyze lipid oxidation and protein decomposition. Values of TBA, VBN, and TMA of all fish did not exceed 0.5 mg MDA/kg, 30 mg/100 g, and 10 mg/100 g, respectively, which are considered edible limits regardless of bromelain or emulsion application. Bromelain modified fish fillets' hardness and adhesiveness to be suitable for elderly food, although it was encapsulated in the emulsion. Thus, spray-dried fish oil W/O/W double emulsion-loaded bromelain can be applied as a fish tenderizer, and this study’s results can be utilized to develop elderly-friendly food.

Recently, the annual emission rate of CO2 that is the main reason for domestic greenhouse gases is the third highest globally, which means it is an extremely serious issue. It is considered that these greenhouse gases affect climate changes. Especially, the emissions of CO2 in the fishing industry are nearly 4.11 million tons each year, occupying 0.7 percent of domestic total emissions. Therefore, this study clearly analyzed fuel consumption of major fish species over the recent five years focusing on large purse seines. It was revealed that mackerels occupied 55.7 percent of total fish catches of large purse seines and 57.5percent of total fishing earnings. Also, fuel consumption was 236.62 liters per ton caught and 179.51liters per million won earned.

본 연구는 근해에서 잡은 고등어의 신선도유지효과를 확인하기 위해 해수 슬러리얼음(SS), 해수 큐브얼음(SC), 수돗물 슬러리얼음(TS), 수돗물 큐브얼음(TC)에 저장하며, 신선도분석을 시행하였다. 각 얼 음 성분 중 세균수는 음용수 기준 이하였고, 암모니아성 질소는 해수 기준치인 11 mg/L를 초과했다. 민물에 비해 바닷물의 탁도가 심했다. 고등어의 일반성분 분석결과 수분 함량이 72.7%, 단백질 20.5%, 지질 5.25%, 회분 함량이 1.3%로 나타났다. 해수 슬러리 얼음은 수돗물 얼음과 비교하여 pH가 낮게 유지되었다. 저장 초기에는 모든 저장소에서 VBN 증가가 억제되었다. 전반적으로 해수빙이 담수 얼음보다 휘발성 염기질소(VBN) 값이 낮게 유지 되었다.