• Environmental and Resource Economics Review
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• v.19 no.4
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• pp.897-914
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• 2010

The translog cost function of Korean Walleye pollock fishery is used to examine the impact of surface water temperature change led by global climate change. Catched of walleye pollock are very sensitive to water temperature and material cost. Elasticities of production to water temperature are -9%, significantly lower than we expected. There may be alternative explanations for the productivity decrease, including the possibility of overfishing and water pollution. However, the impact of climate change is obvious and inevitable. Therefore the government may encourage local fishermen to change from current cold water to warm water fisheries. Moreover continuos monitoring for the possibility of illegal activities at the East Sea. Finally, collaborated political efforts may be needed among the nations in the East Sea to conserve a Walleye Pollock fishery.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.257-258
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• 2003

명태는 우리나라의 동해, 일본 근해, 오호츠크해, 베링해, 알라스카만과 북동태평양 연안을 따라 남부 오레곤까지의 북태평양에 널리 분포하는 냄수성 어종으로 우리나라 동해안에서 어획되는 명태는 주산란장이 함경남도의 마양도와 원산만으로 알려져 있다. 우리나라 동해안에서의 명태 어획량은 1971년에 11천들에서 매변 변동을 보이면서 증가하여 1981년에 166천톤으로 최고어획량을 기록한 후 급격히 감소하여 1988∼1993년에는 연간 2만톤 내외를 어획하였다. (중략)

• Food Science and Preservation
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• v.16 no.5
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• pp.772-781
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• 2009

We investigated the effects of Alaska pollack addition on the quality of Kimchi during 20 days of fermentation at 10C. Alaska pollack was added to salted cabbage at concentrations of 0%, 6%, 12%, or 18% (all w/w). The quality characteristics determined were pH, acidity, salinity, reducing sugar content, color, free amino acid level, and lactic acid bacterial counts, at 4 d intervals over 20 d, during progressive fermentation at constant temperature (10C). Changes in pH, acidity, and reducing sugar content during fermentation were increased when Alaska pollack was added, whereas salinity decreased. Total lactic acid bacterial counts achieved maximum levels on day 8 for Kimchi with 18% (w/w) Alaska pollack, and the other Kimchi samples attained their highest values on day 12. In terms of color, the L, a, and b values of Kimchi rose with addition of Alaska pollack. The free amino acid content of Kimchi increased as the level of added Alaska pollack rose but gradually fell as fermentation progressed. Upon sensory evaluation, Kimchi with 6% (w/w) Alaska pollack scored highest in terms of appearance, texture, taste, and overall acceptance. In conclusion, our results indicate that Alaska pollack has a positive effect on the quality of Kimchi, increasing the content of free amino acids.

• Korean journal of food and cookery science
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• v.28 no.6
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• pp.711-719
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• 2012

The collagens from squid (Todarodes pacificus) skin and Alaska pollack (Theragra chalcogramma) skin were extracted and their physicochemical properties were investigated. The yield was improved with the increase of NaOH concentration and was increased Neutrase than Alcalase in enzymatic hydrolysates. Protein and collagen contents from Alaska pollack skin were 38.3~62.7% and 13.1~28.9%, respectively. All enzymatic hydrolysates also showed high antioxidant activities as NaOH concentration decrease. Composition of their amino acids was mainly glycine and proline. The spectrum of FT-IR of the collagen showed wavenumber at $1,631cm^{-1}$, $1,549cm^{-1}$, $1,234cm^{-1}$ and $3,322cm^{-1}$ representing the regions of amide I, amide II, amide III and amide A, respectively. The decomposition temperature for the collagen was in the range of $300^{\circ}C$ and showed relatively good enough for their thermal stabilities.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.195-205
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• 2020

Oceanic conditions in walleye pollock habitat in the East Sea have shown decadal fluctuations between warm and cold periods in turn. Specifically, sea surface temperature (SST) has shown a dramatic increase between the late 1980s and the middle 2000s, and abrupt decreasing patterns after the late 2000s. Oceanic conditions in the Dong-han Bay (spawning ground) and middle eastern coastal waters (fishing ground), however, indicated different fluctuation trends in SST, increasing in the Dong-han Bay after the late 1980s, and decreasing after the late 2000s. These fluctuation patterns were especially clear in February and March. Sea surface temperature in the middle eastern coastal waters of Korea soared continuously after the late 1980s, but did not show a distinct decreasing pattern after the late 2000s compared with Dong han Bay, except for February SST values. These long term water temperature changes in both walleye pollock spawning and fishing ground are related to variation in walleye pollock landings. Especially, abrupt changes in spawning ground SST can be one of the factors influencing survival in the early ontogenesis of walleye pollock, including egg and yolk larval stages. During the 1980s, the area of suitable spawning temperature (2-5℃) was wider, and the length of Walleye pollock egg and larval stages greater compared with past and present oceanographic environments. However, such patterns did not correspond with the optimal spawning temperature range and greater length of development of walleye pollock during the late 1980s likely triggering a decline in pollock stock. In conclusion, it has been supposed that the dramatic decrease in walleye pollock landings in the East Sea since the late 1980s was caused by increasing water temperature leading to both early mortality and unsuitable spawning conditions.

• Ocean and Polar Research
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• v.30 no.3
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• pp.249-258
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• 2008

Oxygen isotopic composition(${\delta}^{18}O$) of walleye pollock, Theragra chalcogramma, otoliths were measured to investigate interannual and regional correlation with habitat temperature. Specimens were collected from fishermen in Korea and Japan between $1997{\sim}1999$, while seawater temperatures were obtained from Korean and Japanese Oceanographic Data Centers. Seawater temperature was generally lower off the eastern Korean Peninsula than off eastern Hokkaido(Japan). Sagittal otoliths were removed for measurement of ${\delta}^{18}O$ using a micro-drilling technique. In most cases, ${\delta}^{18}O$ and habitat temperature exhibited negative relationship in Korean and Japanese waters. Higher ${\delta}^{18}O$ was observed in Korean pollock compared to Japanese pollock. The marginal parts of otoliths exhibited higher ${\delta}^{18}O$ than cores from both regions. This is an indication that somatic growth of walleye pollock occurs in deeper and cooler waters. Interannual variation in ${\delta}^{18}O$ was also observed. Mean ${\delta}^{18}O$ values acquired from 1997 otoliths were lower(2.15%) than those of 1998(2.67%) and 1999 (2.65%) in Korean pollock. These measurements coincided with changes in observed temperature in Korean waters, in which mean seawater temperature was warmer in 1997 than in 1998 and 1999. In Japanese waters, mean seawater temperature was lowest in 1997, which coincided with highest ${\delta}^{18}O$ values in the same year.

• Korean Journal of Food Science and Technology
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• v.22 no.7
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• pp.786-792
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• 1990

In order to study the possibility of savoury material production from fish flesh(Alaska pollack), as a substrate of fermentation, three strains of Aspergillus oryzae were applied to the flesh solely or with soybean. The fermented flesh were analyzed their amino acid compositions, nucleotide contents and their sensory acceptability. All strains tested were grown vigorously on both substrates. When fish flesh solely used, amino nitrogen($NH_2-N$) and soluble solid (S.S.) contents were $8{\sim}14\;and\;2{\sim}3$ times higher than those of raw flesh, respectively after 7 days fermentation. In case of fish flesh with 10% soybean used, their $NH_{2}-N$ and S.S. contents were $4{\sim}6\;and\;2.6{\sim}3$ times higher than those of raw flesh respectively. It was belived that increment of $NH_2-N$ and S.S. contents were resulted from degradation of fish flesh protein. On the other hand, the nucleotides and their related compounds of both fermented flesh and with 10% soybean were increased comparing with raw flesh. The content of free amino acids of flesh solely and with 10% soybean were $1,435{\sim}4,326mg%(DB)\;and\;5,563{\sim}6,362mg%(DB)$, which increased to between $4.6{\sim}13.9\;and\;11.6{\sim}13.2$ times, respectively after 7 days fermentation. The four amino acids- glutamic acid, histidine, aspartic acid and lysine were major in both flesh solely and flesh with 10% soybean. In sensory evaluation, fermented flesh extracts was more acceptable than anchovy extract. In review of all results, Aspergillus oryzae KFCC 32343 could be successfully used for production of savoury material from Alaska pollack.

• Journal of Life Science
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• v.26 no.11
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• pp.1237-1244
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• 2016

A comprehensive analysis of the genetic diversity and relationship of the cold-water fishery walleye pollock (Theragra chalcogramma), the most abundant economically important fishery resource in the East sea of Korea, has not been carried out, despite its importance in Korea. The present study assessed the genetic diversity and relationship between five walleye pollock populations (Korean population, Russian population, USA population, and Japanese populations) of T. chalcogramma using eight microsatellite DNA (msDNA) markers to provide the scientific data for the preservation and management of the Pollock fishery resource. The results of the analysis of 186 individuals of the Pollock revealed a range of 7.13-10.63 numbers of alleles (mean number of alleles=9.05). The means of observed heterozygosity ($H_O$), expected heterozygosity ($H_E$) were 0.732 and 0.698, respectively. The results of genetic distance, Pairwise $F_{ST}$, UPGMA (UPGMA: un-weighted pair-group method with an arithmetical average) (the phylogenetic tree), PCA (PCA: Principal Coordinate analysis) analysis pointed to significant differences between the Korean population, Russian population, USA population, and Japanese populations, although small (p<0.05). These results shed light on the genetic diversity and relationships of T. chalcogramma and can be utilized for research on the evaluation and conservation of Korean T. chalcogramma as genetic resources.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.362-363
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• 2001

명태는 한국, 일본 그리고 러시아 해역에 넓게 분포하고 있다. 그 중 일본 최대의 산란장인 홋카이도의 A지역(종곡, 유맹, 후지)어획량은 1976년부터 계속 감소하고 있다. 본 연구에서는 어획량 변동 요인을 분석하기 위해서, 일본해역에 있어서의 명태 어획량의 시공간적 변동(시공간적배동)의 특징을 검토한다. 일반적으로 어획량의 변동은 어장에 있어서의 어업형태 또는 내유(來遊)하는 계통군(系統群)의 변화, 해양환경 등에 영향을 받고 있다. (중략)

• 한국해양학회지
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• v.13 no.2
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• pp.26-30
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• 1978

This work concerns morphological studies of Alaska pollak, Theragra chalcogramma(PALLAS), and of the Nogari which is generally known as an immature form of the Alaska pollack. Observations are made to see whether significant differences in the meristic and morphometric characters can be recognized between two groups. Four meristic characters, namely, first anal fin rays, first dorsal fin rays, gill rakers, vertebra and three morphometric characters, namely, head length, snout length, eye diameter are chosen for the study. Results of the analyses reveal that the differences in all the selected meristic characters between Nogari and Alaska pollack are found to be not significant. Differences in the snout length in relation to the head length are found to be not significant . However, the differences in the head length in relation to the body length and the differences in eye diameter in relation to the head length are both found to be significant. In spite of the lack of informations on genetypic variations, it is reasonable to state that the Nogari appears to be a juvenile form of the Alaska pollak, and the differences in certain morphometric measurements between two groups are likely to be associated with the differences in the relative growth rates during the life stages.