• 한국어류학회지
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• 제22권2호
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• pp.121-125
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• 2010

진해만에 산란회유한 대구 친어의 체장에 따른 포란수를 조사하기 위하여 거제수협 외포 위판장에서 산란기인 2008년 12월부터 2009년 2월까지 채집한 45개체의 대구 전장과 포란수를 조사하였다. 산란기 동안 최대 포란수는 520만개 (TL 74.0 cm), 최소 포란수 56만개 (TL 64.0 cm), 평균 포란수 212만개였다. 어체 전장범위별 비교에서는 전장 66~70 cm에서 평균 포란수 169만개, 71~75 cm에서 평균 포란수 260만개로 증가하였다. 진해만 대구는 전장 증가에 따라 포란수도 증가하는 것으로 나타났다. 산란기간 중 전기, 중기, 후기의 평균 포란수는 262만개, 196만개, 165만개로 전기에서 후기로 갈수록 감소하는 경향을 나타냈다. 또한 상대포란수도 포란수와 유사한 경향을 나타냈다. 한편 상대포란수와 체장과의 상관관계는 적은 것으로 나타났고 같은 전장에서 상대포란수가 316~935개로 폭넓게 나타난 것으로 보아 같은 어체 크기라도 진해만으로 산란회유하는 시기에 따라 포란수가 달라질 수 있음을 시사하고 있다.

• 한국어류학회지
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• 제27권2호
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• pp.142-148
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• 2015

2012년 2월부터 2013년 6월까지 남동부해역에서 기선저인망과 호망에 의해 채집된 대구 620 개체의 식성을 조사하였다. 620개체 중 192개체는 먹이가 포함되어 있었고, 428개체는 공위였다. 연구에 사용된 개체의 전장범위는 20.4~95.2 cm였다. 대구는 주로 어류, 새우류, 두족류를 섭식하였고, 소량이지만 집게류, 게류, 곤쟁이류, 등각류, 단각류 등도 섭식하였다. 먹이생물 중 어류의 비율은 대구의 전장이 커질수록 증가하였으나, 계절적 변화는 없었다. 새우류와 두족류의 비율은 성장하면서 감소하였고, 계절적 차이는 뚜렷하였다. 가을부터 겨울까지 주로 새우류가 포함되어 있는 반면, 봄부터 여름까지는 두족류가 많이 포함되어 있었다.

• 한국수산과학회지
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• 제45권4호
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• pp.379-386
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• 2012

The feeding habits of the Pacific cod Gadus macrocephalus were studied by analyzing the stomach contents of 423 specimens caught by coastal gill net in the coastal waters off Jumunjin, Gangwondo, Korea, from January to December, 2011. The size of Pacific cod ranged from 31.0 to 86.5cm in total length (TL). The proportion of empty stomachs was 25.1%. The main prey items were Macrura, Pisces, and Cephalopoda. In order of abundance, the most dominant species of Macrura, were Pandalus eous, Argis lar, and Neocrangon communis, and the most dominant species of Pisces, were Clupea pallasii, Actoscopus japonicus, and Glyptocephalus stelleri. Berryteuthis magister was the most dominant species of Cephalopoda. In terms of variation in feeding habits by growth, Macrura was the most important prey group for G. macrocephalus ranging in TL from 30- to 55 cm, but Pisces was the most important prey group for cod over 56 cm TL. Catch of G. macrocephalus was significantly positively correlated to catch of the three major Pisces prey species Clupea pallasii, Actoscopus japonicus and Glyptocephalus stelleri.

• 한국수산과학회지
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• 제38권4호
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• pp.245-250
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• 2005

The maturity and spawning of Pacific cod, Gadus macrocephalus, was studied using samples caught by gillnets in the East Sea from January to December 2003. Monthly changes of maturity observed with the naked eyes for females showed that maturing Pacific cod appeared from August, and their numbers increased to $83\%\;and\;100\%$ in November and December, respectively. In January, mature and spawning Pacific cod were observed for the first time and composed over $40\%$ of the population. In February, the proportion of spawning individuals increased to over $50\%$, however, the mature individuals decreased to less than $10\%$. In March, mature fish were not found, and all were in an immature (spent) or spawning state. From April to July all fish remained in immature condition. The males maintained this trend with the females, whereas, mature males appeared from November to March. Monthly changes in the gonadosomatic index (GSI) of females and males showed higher values both in January and February and declined sharply in March. The lower value remained until October and then began to increase from November for the female population. For the males, however, this value remained lower until August, and then began to increase from September, and showed higher values in October through December than in January and February. These results indicated that the spawning season of Pacific cod was from December to March, and the main spawning season was from January to February, and the period of the spawning season was longer for males than the females. The diameter of the matured oocytes was 0.80-1.10 mm with a single mode of 0.95 mm. Fecundity was 1,300,000-9,400,000 in total length of 65-95 cm and the relationship between the total length (TL, cm) and fecundity (Fc) was Fc= $180,248\timesTL-10,883,638$. The total length at first maturity was observed at 57 cm for females and 47 cm for males. The size at $50\%$ group maturity was estimated to be 63.9 cm for females and 56.0 cm for males.

• 한국어류학회지
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• 제22권3호
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• pp.195-200
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• 2010

대구 부화자어 대량방류를 위한 기초 연구로서 대용량 부화기를 이용한 대구 수정란 부화 방법을 검토하였다. 기존의 용량 15L와 시험용 42L인 부화기에 수정란을 수용한 결과 9일째 생존율이 48.3%와 50.4%로 나타나 부화기 용량차이에 따른 생존율은 유의한 차이가 없었다. 제작한 실험 부화기와 기존의 원형수조에서 수정란 생존율을 비교한 결과 40.0~71.2%로 부화기에서 높아 대구 수정란 부화에 실험 부화기가 효율적인 것으로 사료된다. 또한 42 L 부화기에 수정란 5,000 mL (약 825만 개)를 수용하여도 높은 부화율을 유지하였다. 결과적으로 대구 수정란 부화 시 대용량 부화기를 이용할 경우, 고밀도로 수용하여도 높은 수정란 생존율 유지가 가능하고 사육 공간과 인력 및 경비를 절감할 수 있을 것으로 생각된다. 또한 원형수조에 비하여 사육수 절약 (6,700 mL/min)과 수정란 그룹별 수용이 가능하다는 장점이 있다.

• 한국수산과학회지
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• 제53권4호
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• pp.530-537
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• 2020

This study compared the survival rates, growth, and fatty acid content of larval Pacific cod Gadus macrocephalus fed with rotifers raised on different enrichment diets. We used four commercial rotifer enrichment products (one domestic, ER1, and three imported, ER2, ER3 and ER4). Twelve 200-L tanks were used, with three replicates per treatment. Larvae were fed rotifers 3 times daily at a rate of 5 rotifers/ml/feeding from 7 to 21 days post-hatch. At the end of the feeding trial, the survival rate and total length of larvae fed ER3 were greater than those of larvae fed ER1, ER2, or ER4. ER3 had the highest proportions of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and polyunsaturated acid (PUFA). Partially reflecting this composition, larvae fed ER3 had the highest proportions of DHA and PUFA. These results show a positive effect of rotifer DHA and PUFA proportions on the survival and growth rates of Pacific cod larvae.

• 수산해양기술연구
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• 제49권3호
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• pp.261-269
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• 2013

The age and growth of the Pacific cod, Gadus macrocephalus were investigated using left sagittal otoliths of 682 individuals collected in the West Sea of Korea from January to December 2007. The seasonal changes in the ratio of an opaque zone to interval between annular rings revealed that the narrow translucent parts of the otolith were annual growth rings formed between February and March once a year. The spawning period was December to January and therefore the duration from fertilization to the complete formation of the opaque zone became thirteen months. From the parameters calculated using the average length when the year ring was formed, the estimated von Bertalanffy growth equations were $L_t=100.0(1-e^{-0.1640(t+0.5247)})$ for females and $L_t=64.6(1-e^{-0.3335 (t+0.3342)})$ for males when is total length in age t.

• 한국수산과학회지
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• 제54권1호
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• pp.46-52
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• 2021

The maturation and spawning of Pacific cod Gadus macrocephalus were inversigated using 2,415 samples collected monthly from January 2017 to December 2019, in the Yellow Sea of Korea. We analyzed monthly changes in gonadosomatic index (GSI), maturity stage, egg diameter (mm), the relations fecundity and total length (cm). The spawning period was February to March. Fecundity varied between 334,836 and 2,099,600 eggs. The relationship between the fecundity and TL of fish was expressed in F=186.86TL2.0954 (R2=0.7359). The percentage of sexually mature females estimated from a logistic function was over 50%, 75% and 97.5% for the size (TL) 39.3, 44.8 and 57.7 cm.

• 한국어류학회지
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• 제34권2호
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• pp.102-112
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• 2022

본 연구는 위내용물 분석과 안정동위원소(δ¹³C and δ¹⁵N) 분석을 통하여 우리나라 동해 북부 연안에 출현하는 명태(Gadus chalcogrammus)와 대구(G. macrocephalus)의 종내 및 종간 먹이자원 분할을 조사하였다. 두 종은 중층성 육식성 어종으로 명태는 저서성 및 중층성 갑각류를 주로 섭식하였고, 대구는 어류를 주로 섭식하였다. 위내용물 분석 결과에 대한 Non-metric multidimensional scaling (nMDS) ordination과 permutational multivariate analysis of variance (PERMANOVA)은 두 종의 종내 및 종간 먹이조성의 차이와 먹이자원 분할을 보여줬다. 안정동위원소 분석 결과 δ¹⁵N 값은 종간 유사하였지만, δ¹³C 값은 대구가 높은 값을 나타내어 두 종간 생태지위 차이를 보여줬다. 명태는 체장 증가에 따라 큰 체장군에서 새우류와 두족류를 더 많이 섭식하는 먹이 전환을 나타냈지만, 대구는 체장군 간 먹이조성이 유사하였다. 안정동위원소 분석에서도 체장군 간 차이를 보였는데, 두 종의 큰 체장군은 작은 체장군에 비해 더 높은 δ¹⁵N 값을 나타낸다. 결론적으로 본 연구는 명태와 대구의 위내용물 분석과 안정동위원소 분석을 통하여 종내 및 종간 먹이 차이와 생태지위 분할의 증거를 보여줬다.

• 수산해양기술연구
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• 제55권1호
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• pp.29-38
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• 2019

In order to investigate the behavioral characteristics of Pacific cod (Gadus macrocephalus) released at the entrance of Jinhae Bay, Korea, the direction and range of movement, swimming speed of the fish were measured with an acoustic telemetry techniques in winter, 2015. Three wild Pacific codes WC1 to WC3 (total length 66.0, 75.0, 76.0 cm; body weight 2.84, 2.79, 3.47 kg, respectively) were tagged with the acoustic transmitter. WC1 tagged with an acoustic transmitter internally by surgical method, WC2 and WC3, externally with the acoustic data logger and a micro data logger for recording audible sound waves including timer release unit. The movement routes of the tagged fish were measured more than five hours using VR100 receiver and a directional hydrophone. The directionality of the fish movement was tested by Rayleigh's z-Test, the statistical analysis, and a statistical program SPSS. Three tagged fishes were individually released on the sea surface around the entrance to the Jinhae Bay on 10 to 24 January 2015. WC1 moved about 13.32 km with average swimming speed of 0.63 m/s for six hours. The average swimming depth and water depth of the seabed on the route of WC1 were 7.2 and 32.9 m, respectively. The movement range of WC2 and WC3 were 7.95 and 11.06 km, approximately, with average swimming speed of 0.44 and 0.58 m/s for 5.1 and 5.3 hours, respectively. The average swimming depth of WC2 and WC3 were 18.7 and 5.0 m, and the water depth on the route, 34.4 and 29.8 m, respectively. Three fishes WC1 to WC3 were shown significant directionality in the movement (p < 0.05). Movement mean angles of WC1 to WC3 were 77.7, 76.3 and $88.1^{\circ}$, respectively. There was no significant correlation between the movement direction of fish (WC1 and WC2) and the tidal currents during the experimental period (p >= 0.05). Consequently, three tagged fishes were commonly moved toward outside of the entrance and headed for eastward of the Korean Peninsula, approximately, after release. It may estimate positively that the tidal current speed may affect to the swimming speed of the Pacific cod during the spring tide than the neap tide.