• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.3
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• pp.215-222
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• 2014

Paralarvae of the common squid, Todarodes pacificus Steenstrup were sampled with the bongo net (diameter: 60 cm, mesh: $333{\mu}m$) by using oblique tow method with the oceanographic research vessel (Tamgu 12) at 21 stations along the southwestern coastal waters of the East Sea in August and September, 2013. Paralarvae were collected 16 ind./$10m^3$ in August and 7 ind./$10m^3$ in September at approximately, and bottom depth was from 70 m to 500 m. Mantle length of paralarvae was from 1.7 to 6.0 mm. Paralavae were distributed mainly in offshore stations in August and near by Cape Janggi in September. Optimum embryo survival temperature ($18-24^{\circ}C$) was formed shallower than 35 m depth for almost stations where paralarvae were existed, and survival temperature ($15-24^{\circ}C$) for embryo stage was located shallower than 75 m.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.1000-1006
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• 2021

The maturity and spawning of the common octopus Octopus vulgaris were studied using 317 samples collected monthly from January to December of 2020 from the coastal waters of Yeosu, Korea. The mantle length (ML) of O. vulgaris ranged from 5.1 to 19.7 cm and body weight (BW) ranged from 117.6 to 3,645.4 g. We analyzed monthly changes in sex ratio, gonadosomatic index (GSI), histological maturity stage, and body weight at 50%, 75% and 97.5% group maturity. The sex ratio was 1:1.02, which was not significantly different from the value that expected. Based on histological observation of the gonad development and gonadosomatic index, the spawning periods lasted throughout the year, with peak spawning periods estimated from March to April and July to August. The percentages of sexually mature females estimated using a logistic equation were over 50% at 554.46 g BW, 75% at 1,134.38 g BW and 97.5% at 2,474.22 g BW respectively.

• Animal cells and systems
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• v.8 no.1
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• pp.33-40
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• 2004

Reproductive cycle and spawning rhythm with lunar cycle of the ascidian, Halocynthia hilgendorfi ritteri were investigated by histological examination. The specimens were sampled in the coastal waters of Yongdam, northwest of Jeju Island, Korea, from November 2001 to January 2003. H. hilgendorfi ritteri is a synchronous hermaphrodite; the gonads are located in the mantle. The reproductive cycle can be grouped into the following successive stages in the ovary: growth (February to June), vitellogenesis (April to September), mature (July to December), spent (November to February), and recovery (December to April). Likewise, in the testis, the stages observed were: growth (October), mature (October to December), spent (November to February), and resting (January to September). Major spawning probably occurs between November and January, when water temperatures decrease. The histological observations of the gonads suggested that this species is a multiple spawner during the spawning period. Spawning occurred between the new moon and full moon, and again between the full moon and new moon, suggesting that the spawning rhythm is influenced by the lunar cycle.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.42-48
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• 2006

Analysis of stomach content for common squid was carried out to investigate the difference in seasonal and ontogenetic feeding behavior. Totals of 1368 common squid were collected monthly off Busan from September 2004 to August, 2005. Size range of common squid was 8.5-31.8 cm mantle length (ML) during the study period. Of the 1368 stomachs examined, 599 specimens (43.8%) were empty. Stomach contents indicated that common squid was carnivore: Large portion of stomach contents consisted of fish and mollusca (mainly common squid). The stomach contents index (SCI) seemed to increase with size, though there was no statistical difference between size classes significantly. Cannibalism was minimum in size range of 15-20 cm ML, but was steadily increased with size. Cephalopods were the major prey during spring and summer when common squid were small, but fish replaced it during autumn and winter when they became large.

• Parasites, Hosts and Diseases
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• v.33 no.1
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• pp.1-8
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• 1995

Gymnophalkides seoi has drawn medical attentions since the discovery of the first human case and a highly endemic area on a southwestern coastal island of Shinan- gun, Korea. Marine bivalves especially oysters were strongly suspected as the source of infection. In this study the oysters, Crassostrea girns, naturally produced (rom the endemic area were examined whether they contain gymnophallid metacercariae. All of 50 oysters examined were infected with the metacercaviae of a gymnophallid, with the metacercarial density per oyster of 610 on average (2-4,792 in range). Later they were identified as G. seoi by obtaining adult worms from experimental mice. The metacercariae were unencysted, and firmly attached on the mantle surface of the oysters with their oral sucker. In sectioned specimens they were equipped with the ventral pit, a peculiar organ of the genus Gymophalloides, and non-muscular genital pore which was connected dorsally to the seminal vesicle. The seminal vesicle was in a great majority mono-sac. By this study, it has been confirmed that the oyster is a 2nd intermediate host of G. seoi as well as the major source of human infection with this fluke.

• The Korean Journal of Malacology
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• v.29 no.4
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• pp.381-384
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• 2013

One specimen (13.4 cm ML) of Chiroteuthis picteti belonging to the family Chiroteuthidae, firstly collected from Songjeong, Southeast coastal water of Korea on May 18, 2013. It was identified as C. picteti based on the following combination of morphological character: mantle slenderly cylindrical; fin oval shape, both lobes having no anterior free lobe, FL 58.2% of ML; arms long with a formula IV > III > II > I. We propose a new Korean name, "Kin-pal-o-jing-eo-gua", "Kin-pal-o-jing-eo-sok", and "Kin-pal-o-jing-eo" for the family, genus and species, respectively.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.437-441
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• 2014

One specimen of Argonauta argo belonging to the family Argonautidae, was collected Songjeong, southeastern coastal water of Korea on July 12, 2010. The specimen, a mature female of 76 mm mantle length and 97 mm shell length. The number of ribs are 56 in shell. The shell is distinct between the arm I's. The I arm has expanded, hemi-discoidal web to which the distal part is fused together. The funnel is large and exceeds the base of arm IV. The arms formula is IV > $II{\fallingdotseq}III$ > I. The specimen was female. Fecundity was 155,203 eggs. This species is pelagic octopus and important prey item of dolphin.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.1
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• pp.1-9
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• 2010

Experimental fishing was carried out to compare fishing status according to the codend mesh size (raschel, 15mm, 25mm, 35mm, 45mm) of stow net on anchor in the coastal waters of Seocheon after manufacturing five kinds of fishing gears and commercial fishing boat (7.93 tons) was used for it. Total catches of raschel, 15mm, 25mm, 35mm, 45mm codend were 816,949g, 203,994g, 1,405g, 51,576g, 194g in September and 40,545g, 66,974g, 14,692g, 12,647g, 12,655g in October. Dominance species were anchovy (Engraulis japonicus) in raschel codend, largehead hairtail (Trichiurus lepturus) in 15mm and 35mm in September, and the amount of catches was very small in 25mm and 45mm codend due to the fishing gear damage. In October, dominance species were anchovy and beka squid (Loligo beka) in raschel, 15mm, 25mm codend, and cuttlefish (Sepia esculenta) and beka squid were mainly caught in 35mm and 45mm codend. In addition, total length of anchovy and cardinal fish (Apogon lineatus) were increased according to the increase of codend mesh size but there was no difference in the mantle length of cuttlefish and loligo beka.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.1
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• pp.58-66
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• 2019

Paralarvae of the common squid, Todarodes pacificus, were sampled with the bongo net (diameter: 60 cm, mesh: $333{\mu}m$) with a research vessel (Tamgu 20) at 18 stations along the coastal waters of the Yellow Sea in spring and autumn from 2013 to 2015. Over this period, 4 Paralarvae were collected. Paralarval density was $0.1inds./1,000m^3$ and $0.2inds./1,000m^3$ in autumn 2014 and $0.1inds./1,000m^3$ and $0.2inds./1,000m^3$ in autumn 2015. The range of mantle length for paralarvae was from 1.5 to 8.3 mm. Survival temperature ($15-24^{\circ}C$) for embryo stage and paralarvae was found in locations shallower than 56 m of depth at stations which were sampled for paralarvae.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.1052-1057
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• 2021

The diet composition of common flying squid Todarodes pacificus was studied using 1,084 specimens collected through trawl and jigging from June 2018 to June 2020 in the East Sea of Korea. The mantle length (ML) of the collected individuals ranged from 13.6 to 31.1 cm. Todarodes pacificus is a carnivore. In the study area, T. pacificus was observed feeding mainly on fish and cephalopods, in addition to small quantities of crustaceans. The calculated trophic level value for T. pacificus was 4.10. Small individuals (ML, <18.0 cm) mainly fed on cephalopods, while intermediate (ML, 18.0-23.0 cm) and large (ML, ≥23.0 cm) individuals fed mainly on fish and occasionally on cephalopods. Overall, as the body size of T. pacificus increased, the mean weight of the consumed prey increased (one-way ANOVA, P<0.05).