• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.1
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• pp.11-15
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• 2009

The proposal of the $CO_2$ ocean sequestration necessitates a thorough understanding of its consequences to aquatic organisms. This paper describes acute toxic responses to high $CO_2$ environment of a cephalopod, Octopus vulgaris. O. vulgaris was chronically cannulated in the abdominal aorta and recovered in a restrained chamber. Acid base variables as well as ion concentrations were estimated in samples of the blood collected from recovered O. vulgaris. 100% mortality occurred within 72h during exposure to 3%-$CO_2$ environment. Hemolymph pH significantly decreased after 30 min during exposure to 1%-$CO_2$ environment without any compensation thereafter. $[HCO_3^-]$ significantly increased from 2.2 mM at 0h to 7.8 mM at 8h, but gradually decreased thereafter. Hemolymph ions $([Cl^-],\;[Na^+],\;[K^+])$ showed no significant changes. O. vulgaris may be more sensitive than teleost, yellowtail, flounder and dogfish.

• Applied Microscopy
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• v.32 no.3
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• pp.247-255
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• 2002

In this study, we carried out immunostaining and immunogold labeling with antibodies to serotonin and somatostatin to examine the characteristics and functions of the neurons that secrete neurotransmitters in optic lobes of Todarodes pacificus and Octopus minor. As a result of immunostaining with anti-somatostatin, the nerve cells of Todarodes pacificus reacted as similar to the anti-serotonin, but in Octopus minor, only large cells in the outer granule cell layer reacted positively. In the immunogold labeling with anti-serotonin, the nerve cells in the inner grande cell layer and medulla of Todarodes pacificus reacted strongly, 30 gold particles being labeled per $0.5{\mu}m^2$ of the cytoplasm. However, in Octopus minor, only 17 gold particles were labeled, which stated a weak reaction. On the other hand, in the anti-somatostatin case, the nerve cells in the outer and inner granule cell layers and medulla of Todarodes pacificus showed strong reaction, 30 gold particles being labeled per $0.5{\mu}m^2$ of the cytoplasm while the nerve cells in the outer granule cell layer of Octopus minor reacted weakly, about 3 gold particles being labeled per the equivalent area. As a result of immunostaining and immunogold labeling with two types of antibodies to each part of the optic lobes, we found that the reactive nerve cells were distributed differently in the two species. In particular, the degree of reactivity to the immunostaining and immunogold labeling appeared stronger in Todarodes pacificus than in Octopus minor.

• Journal of Food Hygiene and Safety
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• v.34 no.5
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• pp.502-507
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• 2019

Cephalopods are one of the most important fishery resources in the world because of their desirable taste and nutritional value. In south Korea, one of the countries in which a large amount of seafood is consumed, cephalopods (e.g., octopus, squid, and cuttlefish) have an annual consumption rate of over 400,000 metric tons. In this study, octopus and squid products (n=28) sold on the market were monitored by analyzing sequences of DNA barcode markers (cytochrome c oxidase subunit I and 16S ribosomal RNA genes). For species identification, the NCBI BLAST database was screened with the sequences and analyzed as a query. In this BLAST search, twelve squid products showed 99-100% sequence identity to Dosidicus gigas (n=3) and Todarodes pacificus (n=9). In the case of the other 16 products that were declared using octopus as raw materials on the labels, six products were identified as Cistopus taiwanicus (n=1), Amphioctopus marginatus (n=1), Scaeurgus unicirrhus (n=1), and Dosidicus gigas (n=3). Monitoring results indicated that a significant percentage (37.5%) of mislabeling was present in octopus products sold on the South Korean market.

• Journal of Marine Life Science
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• v.8 no.1
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• pp.1-7
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• 2023

This study was performed to understand the reproductive ecology of cephalopods, described the microanatomical structure of the male reproductive organs and spermatophore in the common squid, Todarodes pacificus, a major cephalopods in Korea. The common squid was gonochorism and had sexual dimorphism, the color of the reproductive organs reflected on the mantle and the presence of the hectocotylus. Male reproductive organs were composed of testis, primary vas deferens, spermatophoric gland (seminal vesicle), spermatophoric sac (Needham's sac) and secondary vas deferens. The male has specialized reproductive organs such as the spermatophore forming organ, spermatophoric gland. Testis was histologically a seminiferous tubule type. The primary vas deferens was a thin and inverted triangular spring-like form that connected from the rear of the testis to the spermatophoric gland. Inside, it was filled with sperm of basophilic in H-E stain. The spermatophoric gland is an irregular oval connected to the primary vas deferens and spermatophoric sac, and there were a number of tubular glands. The spermatophoric sac is a tubular structure located between spermatophoric gland and secondary vas deferens, and a number of spermatophores have been identified in the lumen. The secondary vas deferens was connected to the posterior of the spermatophoric sac and had a spermatophore inside. The spermatophore was a long, transparent tube about 22 mm long, with a sperm mass inside.

• Korean Journal of Ichthyology
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• v.32 no.1
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• pp.8-13
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• 2020

The feeding habits of oriental bonito (Sarda orientalis) were studied using 288 specimens collected in the coastal waters of Jeju Island, Korea from January to December 2015. Oriental bonito is pelagic piscivore that consumes mainly fishes especially Engraulis japonicus and Scomber japonicus. Its diet also includes small quantities euphausiids, amphipods and cephalopods. Oriental bonito showed ontogenetic changes in feeding habits. Although fishes were the primary food consumed by all size groups, the ratio of fishes was slightly increased as body size increase. There also was a significant relationships between mean prey number and weight according to size class and season.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.4
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• pp.317-325
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• 1990

The attraction activity of the natural baits for sea eels(Astroconger myriaster) was surveyed by using fishing traps in the 3 different fishing ground of southern coastal waters of Korea. Twenty four different baits were experimented and weight for each bait was 50g, the optimal minimum weight owing to our preliminary test. Among the above 24 baits, anchovy(Engraulis japonica), sardine(Sardinops melanosticta), or marine worms(Neanthes japonica)were most effective. In case of sardine bait, the body showed higher attraction activity than the head or viscera and the builded juice of anchovy or sardine showed higher attraction activity than spoiled one.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.191-197
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• 1999

Stomach contents of hairtail, Trichiurus lepturus collected in the Nakdong River Estuary were examined quantitatively. T. lepturus was a carnivore which consumed mainly fishes, crustaceans (such as copepods, euphausiids and shrimps) and chaetognaths. Its diets included small quantities of small squids. T. lepturus showed ontogenetic progression of three feeding stages : an initial feeding stage was a planktivorous stage in which copepods were the major food item, followed by a mixed feeding stage in which euphausiids, mysids, shrimps, chaetognaths and fishes were the major food items, and finally a piscivorous stage in which fishes were the major food item. Especially anchovies were heavily selected by large T. lepturus.

• Korean Journal of Ichthyology
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• v.12 no.1
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• pp.54-61
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• 2000

Feeding habits of Zoarces gilli collected in the coastal water off Gadeok-do, Korea from March 1998 to February 1999 were studied. Z. gilli was a carnivore and consumed mainly shrimps, gammarid amphipods, fishes, bivalves and cumaceans. Its diets also included small quantities of copepods, caprellid amphipods, ostracods, crabs, squids, gastropods, ophiuroids and polychaetes. It showed ontogenetic changes in feeding habits. Individuals of small size (10~15 cmSL) fed mainly on small prey organisms such as gammarid amphipods, bivalves, cumaceans and ostracods. However, larger shrimps and fishes were heavily selected with increasing fish size.

• Korean Journal of Ichthyology
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• v.10 no.2
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• pp.155-163
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• 1998

To determine diel and seasonal variations in abundance and species composition of fishery resources, day and night samples were collected by a bag net from April through November 1997 off Kogunsan-gundo. A total of 75 species was collected. The total catch was consisted of 71% fish, 18% shrimps, 7% cephalopods and 4% crabs. Pholis fangi and Engraulis japonicus predominated, and accounted for 87% of the total number of fish collected. Most of them were larvae and juvniles. P. fangi and Ammodyres personatus occurred from April to June, and E. japonicus occurred from July to November, suggesting that they used the coastal areas as nursery ground at the different season to avoid competition. Dominant fish larvae and juveniles showed the significant diel difference in catch.

• Korean Journal of Ichthyology
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• v.20 no.1
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• pp.45-53
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• 2008

Feeding habits of Pseudoblennius percoides collected from the eelgrass bed in Dongdae Bay from January to December 2005 were studied. P. percoides was a carnivore which mainly consumed fishes and caridean shrimps. Its diets included small quantities of mysids,amphipods (gammarid amphipods and caprellid amphipods), copepods, cephalopods, polychaetes,and crabs. P. percoides undergoes significant size-related changes; smaller fish (<3.0 cm SL) prey mainly copepods, gammarid amphipods, and mysids while the proportion of caridean shrimps and fishes increases with fish size. Fishes and caridean shrimps were major prey organisms for all seasons. Dietary breadth of P. percoides was lower with fish size and seasons.