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.

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.

This study analyzed annual catch trend during 45 years and monthly catch of the least 10 years (2005∼2014) for chub mackerel caught in the Korean coastal waters. To determine fishing status of chub mackerel, fork length measurements were conducted at least twice every week for 100 individuals randomly selected at the Busan Cooperative Fish Market from January of 2012 to December of 2014; and biological characteristics and proximate composition (moisture, protein, fat, ash) were analyzed by length class (I∼IV) on a monthly basis from January to December of 2014. Monthly catch trend showed low level below 5,000 mt from February to July, whereas high level above 15,000 mt from October to December. For the period between 2012 and 2014, annual average catch proportion of juvenile were relatively high at 68.1%, 53.1% and 53.2% from January to April, before spawning season, while those were low at 21.5%, 20.7% and 29.12% from June to November. As for the change in the proximate composition per 100 g of muscle, protein and ash did not change much by seasons and length class, whereas fat and moisture contents showed large fluctuations and complementary relationship between the two factors. Regardless of length class, monthly average fat content, containing Omega-3, showed the lowest at 7.18 g in April and highest at 19.27 g in December, which exhibited 2.6 times difference from one another. Regardless of fishing seasons, fat content by length class were 19.06 g for the class I and 6.43 g for the class IV, which showed three times difference. Fat contents of the class I were high at 26.97 g and 27.19 g in November and December, while low at 8.37 g and 9.99 g in April and May. Especially, fat contents from January to May were 5.0 g, which was the lowest. Therefore, it is expected that consumer could indirectly contribute fisheries management through their understanding and wise consumption based on fishing status and fluctuation of proximate composition.

The distribution of eggs and larvae of mackerel, Scomber japonicus was examined in the coast of Jeju island, Korea in spring from April to May in 2013 and May to June in 2014. In the monthly variations of mean abundances, as a whole, mackerel eggs were observed abundantly in April, 2013, and mackerel larvae were observed abundantly in June, 2014. Especially, high densities over 5,000 ind./1,000 m3 of mean eggs abundances were observed in the eastern part of Jeju Island where is water temperature was over 18℃. It can be inferred that these areas were major spawning grounds of mackerel around Jeju island, and that it may be caused by influences of the Tsushima warm current.

In order to offer data about fisheries resources management and prediction of catch on large purse seine fisheries, the fluctuation of the fisheries condition and distributions of fishing ground for mackerel were analysed with monthly catch data for 1990.2009. The overall catch has decreased to about 70% since 1997, with approximately 70% of the mackerel (Scomber japonicus) catch and monthly fluctuations showing a similar pattern. Monthly distribution of fishing ground is like distribution of mackerel in large purse seine fishery. The main fishing grounds are near Jeju Island and the Yellow sea with the main fishing season existing between October to December. The catches fluctuations and distribution of fishing ground were related to the effect of regime shifts. Therefore, in order to prediction of catch on large purse seine fisheries should be studied these relationships.

In this study, the alkiline water washing condition of mackerel(Scomber japonicus) dark meat was investigated to improve processing conditions of red muscle fish meat paste heating gel. Chemical alkaline water(CWM) and electrolytic alkiline water(EWM, pH 12) were used for washing the mackerel raw meat. Washed meats were minced with 2.5% salt and heated at 90℃/15 min to testing texture profile analysis. Moisture of CWM and EWM was increased with both washing times(p<0.05). Crude lipids and protiens were decreased with washing times. Lightness of chemical alkaline water washed mackerel heated paste gel(CWHPG) was higher than electrolytic alkaline water washed mackerel heated paste gel(EWHPG). Redness and yellowness were more decreased than control meats. Jelly strength of CWHPG and EWHPG was not increased more than 2 times wased meat and was increased with protein decrease. Texture profile analysis, max force1 of CWHPG and EWHPG was higher hardeness than the control meat except gel strains. From these results, it could be suggested that electric alkialine water washing is also effective in advance the red meat paste heating gel process of kamaboko industry.

고등어를 습식법으로 인공 수정한 난을 대상으로 난발생 및 자치어 발육과정을 관찰하였다. 수정란의 형태는 구형의 분리부성란으로 유구는 1개를 가지고 있었으며, 난경은 0.94～1.02 ㎜(평균 0.95±0.03 ㎜)였다. 부화에 소요된 시간은 수온 20±0.5℃에서 51시간이 소요되었다. 부화 직후 자어의 전장은 2.52～3.0 ㎜(평균 2.75±0.04 ㎜)로 난황을 달고 있었고, 입과 항문은 아직 열려 있지 않았으며, 근절은 28～31개였고, 눈에는 흑색소포 소포가 착색되어 있었다. 부화 후 2일째의 전기 자어는 3.12～3.63 ㎜(평균 3.39±0.05 ㎜)로 난황이 완전히 흡수되었다. 부화 18일째 후기 자어는 전장이 8.45～12.32 ㎜(평균 10.85±4.36 ㎜)로 꼬리말단이 굽어지기 시작하면서 가슴지느러미, 등지느러미, 꼬리지느러미의 줄기가 형성되었다. 부화 25일째에는 44.12～58.72 ㎜(평균 55.95±6.74 ㎜) 외부 형태가 성어와 같은 치어기에 도달하였다.