• 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.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.127-133
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• 2009

The common octopus, Octopus vulgaris is commercially important species in Korea. Korean fishing vessels have actively caught it. However, the study of this species has been poorly known. Therefore, the purpose of this study is to provide information about maturation and spawning period of this species. Samplings have been monthly collected in Tongyoung and Sacheon of Gyeongsangnam-do, using traps. A total of 748 individuals were sampled from February 2007 to January 2008. We analyzed monthly changes in maturity stages, gonadosomatic index, total weight at 50% group maturity. The octopus total weight was between 128.6 and 3381.4 g. Females were distributed between 129.8 and 3381.4 g and males between 128.6 and 2378.4 g. The spawning periods were May to June and September. The total weight at 50% group maturity was estimated to be 919.6 g.

• The Korean Journal of Malacology
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• v.24 no.3
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• pp.161-166
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• 2008

Samples were collected monthly from coastal water around Tongyeong and Sacheon in Gyeongsangnam-do, Korea, using traps. A total of 748 Octopus vulgaris were sampled from February 2007 to January 2008. Monthly changes of maturity stages and sex ratio of the common octopus were observed. Mean biomass (total wet weight) of the female specimens ranged from 129.8 to 3,381.4 g and that of the male specimens ranged from 128.6 and 2,378.4 g. The spawning periods were May to June and September. The fecundity ranged from 5,715 eggs at 252.0 g to 240,990 eggs at 3,381.4 g of total wet weight. The relationship between total wet weight (TW) and fecundity (F) was F = 26.539 $TW^{1.1548}$ ($r^2=0.8199$) and fecundity increased with total wet weight. Sex ratio was not significantly different from the 1:1 (p > 0.05).

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.280-288
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• 2018

In this study, an approach for the analysis of the five cephalopod species (octopus, long-arm octopus, squid, wet-foot octopus, beka squid) consumed in the Republic of Korea is developed. The samples were collected from the Southeast Asian countries Thailand, Indonesia, Vietnam, and China. The SYBR-green-based real-time qPCR method, based on the mitochondrial DNA genome of the five cephalopods was developed and validated. The intergroup variations in the mitochondrial DNA are evident in the bioinformatic analysis of the mitochondrial genomic DNA sequences of the five groups. Some of the highly-conserved and slightly-variated regions are identified in the mitochondrial cytochrome-c-oxidase subunit I (COI) gene, 16s ribosomal RNA (16s rRNA) gene, and 12s ribosomal RNA (12s rRNA) gene of these groups. To specify each five cephalopod groups, specific primer sets were designed from the COI, 16s rRNA and 12s rRNA regions. The specific primer sets amplified the DNA using the SYBR-green-based real-time PCR system and 11 commercially secured animal tissues: Octopus vulgaris, Octopus minor, Todarodes pacificus, Dosidicus gigas, Sepia esculenta, Amphioctopus fangsiao, Amphioctopus aegina, Amphioctopus marginatus, Loliolus beka, Loligo edulis, and Loligo chinensis. The results confirmed by a conveient way to calculate relative amplification levels between different samples in that it directly uses the threshold cycles (Ct)-value range generated by the qPCR system from these samples. This genomic DNA-based molecular technique provides a quick, accurate, and reliable method for the taxonomic classification of the animal tissues using the real-time qPCR.

• 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.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.2
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• pp.113-120
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• 2022

The purpose of this study is to provide information about annual variations in catch size and changes in reproductive biology in the common octopus, Octopus vulgaris, a commercially important species in Jeju Island. Samples were collected from coastal waters of Jeju Island, Korea by coastal trap fishery from January to November 2021. Octopus vulgaris have been decreasing in this region since 1984. The mantle length (ML) ranged from 4.5 to 17.8 cm and body weight (BW) ranged form 88.5 to 2,657.5 g. A χ²-test revealed that the number of males was significantly greater than females (χ² = 32.712, df = 10, P<0.05). Mature females were found from January to July and male occurred January to August. The gonadosomatic index value was higher from July to August than other months. The relationship between mantle length and body weight was BW = 2.4527ML^2.3139 (female) and BW = 2.6785ML^2.3159 (male). At 50% group maturity, female and male average weight was estimated to be 554.7 g and 330.6 g, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.728-733
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• 2023

The diet composition of octopus Octopus vulgaris was studied using 392 specimens collected from January to December 2020 in the coastal waters of Yeosu, Korea. The body weight ranged from 86.4 to 3,645.4 g. The most important prey item in the diet of O. vulgaris was decapods, which constituted 43.9% in ranking index (%RI). The second largest prey item was Pisces (%RI=27.9%), and cephalopods (%RI=21.8%) constituted the third largest prey item. The average trophic level of O. vulgaris was 3.97±0.59. Ontogenetic changes were significant among size classes (<400 g, 400-800 g, ≥800 g). The small size class (<400 g) mainly fed on decapods, whereas the medium (400-800 g) and large size (≥800 g) classes mainly fed on cephalopods and Pisces, respectively. The dietary composition varied significantly with season.

• Journal of Aquaculture
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• v.10 no.3
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• pp.301-310
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• 1997

To investigate a possibility of the species genetic relationship for the soluble proteins analysis on the class Cephalopoda in the Yellow Sea, the isolate eye, muscle and liver proteins from five species (Sepia esculenta, Sepiella japonica, Loligo chinensis, Loligo beka and Octopus minor) were analysed using different electrophoretic techniques (Davis-polyacrylamide gel electrophoresis, SDS-PAGE, exponential gradient SDS-PAGE, thin-layer isoelectro-focusing and two-dimensional PAGE). The average molecular weight of the soluble eye and muscle proteins was estimated at 35-50 KDa, separated b the exponential gradient SDS-PAGE. It was corresponds to that of electrophoretic patterns by t재 dimensional PAGE. By which the thin layer IEF, the target proteins showed a reasonable specificity based on their isoelectric points (pI) 7.5-8.5.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.57-66
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• 2020

The purpose of this study was to provide information about annual variations in catch size and changes in reproductive biology in the common octopus Octopus vulgaris, a commercially important species. Samples were collected from coastal waters off Gyeongnam, Korea, by coastal trap and coastal complex fishery from February to December 2018. Octopus vulgaris have been decreasing in this region since 2007 and catch prices have been increasing. The mantle length (ML) of O. vulgaris ranged from 1.2 to 21.2 cm and body weight ranged from 42.6 to 5,537 g. The sex ratio differed significantly from what was expected, at 0.45:0.55 (P<0.05). Mature females were found from February to December, except in October and November, and males occurred from February to December, except in October. The gonadosomatic index value was higher from May to September than in other months. The total number of eggs in fecund individuals ranged from 40,280 in 578.1 g of body weight to 138,994 in 1,666.5 g of body weight. The relationship between body weight and fecundity was F=76.486BW^1.0087 (r²=0.7897). At 50% group maturity, average weight was estimated to be 636.35 g, while it was 969.30 g at 75% maturity and 1736.55 g at 97.5% maturity. This study highlights changes in catch size and reproductive biology between 2007 and 2018. These results provide basic evidence that may be used to establish regulatory policy for O. vulgaris fisheries.