• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.735-742
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• 2003

In order to develop a logical method for using selective fishing gear, the behaviour and habits of the aquatic animals must be investigated. However, until now, little national research has been carried out to investigate the behaviour and habits of the common octopus (Octopus minor). The purpose of this study henceforth, is to compile necessary behavioral data to develop fishing gear to catch the common octopus. Behaviour and habits of the common octopus were observed while breeding in a water tank from February to May, 2003. The feeding habits of common octopus are more vigorous at night than in the daytime. The common octopus feeds on 1-4 bait crabs per day and consume each crab in 40-50 min. The sensory organs of the common octopus are more influenced by the sense of touch and smell, than by vision. Using live bait is more effective and advantageous than using dead bait, as the common octopus responded more to live bait. The hiding habits of the common octopus were very intensive, as they hid around all the shelters that were provided in this study. They demonstrated territorial behavior and struggled to maintain their sphere of influence. In addition, out of the various colors for shelters and bait supplied, the common octopus preferred light colors.

• The Korean Journal of Legal Medicine
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• v.42 no.4
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• pp.168-171
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• 2018

In Korea, small octopus (Octopus minor) and webfoot octopus (Octopus ocellatus) are food items and fatal laryngeal choking due to ingestion of live octopus is not uncommon. We recently encountered two autopsy cases of accidental choking on small octopus and webfoot octopus. Case 1 involved a 58-year-old fisherman who ingested two live webfoot octopuses in his fishing boat and collapsed. He was immediately taken to the hospital but died. During autopsy, one of the webfoot octopuses was found between his pharynx and esophagus; it was obstructing the epiglottis and upper esophagus. His blood alcohol concentration was 0.140%. Case 2 involved a 55-year-old man who ingested an intact body part of a small octopus and was found dead in his house. He had a history of cerebral infarction and angina pectoris. During autopsy, an intact body part of the small octopus was found to be lodged in the laryngeal inlet.

• Fisheries and Aquatic Sciences
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• v.24 no.6
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• pp.207-218
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• 2021

This study evaluated the risk of foodborne illness from highly pathogenic Vibrio spp. (Vibrio vulnificus and V. cholerae) by raw whip-arm octopus (Octopus minor) consumption. In total 180 samples of raw whip-arm octopus were collected from markets and examined for the prevalence of V. vulnificus and V. cholerae. Predictive models describing the kinetic behavior of Vibrio spp. in raw whip-arm octopus were developed, and the data on amounts and frequency of raw whip-arm octopus consumption were collected. Using the collected data, a risk assessment simulation was conducted to estimate the probability of foodborne illness raw whip-arm octopus consumption using @RISK. Initial contamination levels of Vibrio spp. in raw whip-arm octopus were -3.9 Log colony-forming unit/g, as estimated by beta distribution fitting. The developed predictive models were appropriate to describe Vibrio spp. in raw whip-arm octopus during distribution and storage with R² values of 0.946-0.964. The consumption frequency and daily consumption amounts of raw whip-arm octopus per person were 0.47% and 57.65 g, respectively. The probability of foodborne illness from raw whip-arm octopus consumption was estimated to be 8.71 × 10^-15 for V. vulnificus and 7.08 × 10^-13 for V. cholerae. These results suggest that the risk of Vibrio spp. infection from raw whip-arm octopus consumption is low in South Korea.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.199-204
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• 2022

The Pacific giant octopus (Enteroctopus dofleini) is one of the most important species in the East Sea fishery of Korea. The annual production of Pacific giant octopus in 2021 was 3,880 metric ton between Gangwon province and Gyeongsangbuk province. Most of the fishing gears for the octopus fishery were based on behavioral properties such as thigmotaxis and chemotaxis. Wooden octopus box is also one of the fishing gears, which is application of thigmotaxis for the octopus capture in fishing industry. In this study, the tank experiments were designed to examine the behaviour and the effect of surface roughness to the infiltration of the octopus quantitatively. Three different types of octopus boxes were used for the experiments with different surface roughness on the average of 701.6 ㎛, 141.7 ㎛ and 2.09 ㎛ for each gear. 22 trials were conducted from June to September 2021. The normality of the experiments was tested using Shapiro-Wilk normality test (p-value < 0.05). The significance of results was conducted by Kruskal-Wallis rank sum test (Chi-squarded = 21, Degree of freedom = 3, p-value < 0.05). The use of wooden octopus box with rough surface was found to enhance the catch efficiency and observe infiltration behaviour of the octopus frequently.

• Journal of Environmental Health Sciences
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• v.36 no.5
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• pp.435-439
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• 2010

In Korea, food-risk shock announcements are made one or more times annually; such as last September, 2010 when Seoul City revealed a very high concentration of cadmium in small octopus intestines sold in Korea. As a result, consumers avoided eating domestic as well as imported small octopus. Fishermen protested against Seoul city; however, the Korean Food and Drug Administration (KFDA) announced that small octopus intestines pose no safety risk. The conflict between KFDA and Seoul City on the safety of small octopus intestines amplified the confusion of consumers. The small octopus cadmium shock resembled previous food-risk shocks in many respects. Effective risk communication is important in resolving food risk shocks as risk affects people case-by-case; for example people who do not eat small octopus intestines should not be at any risk, but those who do enjoy small octopus intestines, especially one more times per week, could be at risk. Therefore, it is necessary to communicate different risk messages to people or groups with different eating habits. From this point of view, the risk message conveyed by the KFDA on small octopus intestines was not appropriate.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.200-207
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• 2013

This paper presents the mesh selectivity of a net pot for common octopus Octopus minor for the sustainable resources management of common octopus. The filed experiments were carried out the total 10 times in the southern part of coastal sea in Korea from March to May in 2010 using net pots of five different mesh sizes (16, 18, 20, 22 and 26mm). The test of size selectivity, indicated a 50% selection value on the logistic master curve of 3.195, whereby 50% of individuals with a mantle size of approximately 70.3mm selected a mesh size of 22mm. Considering that 50% of common octopus entering sexual maturity have a mantle size of 70.6mm, the optimum mesh size should be equal to, or larger than 22mm.

• Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.1-8
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• 2012

The geographical distribution of the toxic blue-lined octopus (commonly known as the blue-ringed octopus), Hapalochlaena spp., around the East/Japan Sea was investigated. Observation records of the octopus were gathered using commercial search engines on the Internet. A questionnaire to complement and enhance the base data was conducted that targeted fishermen from areas where the octopus was most likely to occur, i.e., the southeast coast and islands of Korea in the East/Japan Sea. Overall, 32 observational records of the blue-lined octopus were found from Korea and Japan. In Korea, only one record, from 2003, was found on a website; none of the 240 fishermen who participated in the questionnaire reported seeing blue-lined octopus. However, a total of 31 observations of the blue-lined octopus from 2004 to July 2010 were found from 17 different regions in the East/Japan Sea and neighboring waters in Japan. Twenty-two cases were from coastal Honshu Island, and nine were from the west coast of Kyushu Island, Japan. The northern distributional boundary of the blue-lined octopus on the Japanese coast was off Fukui Prefecture around latitude $36^{\circ}$10' N. Our results indicate that the blue-lined octopus is distributed extensively along the Japanese coast, at a low frequency, in the East/Japan Sea.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.193-198
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• 2022

In this study, for the purpose of reducing the catch of small giant octopus in a net pot, an escape experiment of octopus was performed on five types of escape rings of different sizes. As a result of the experiment, the smallest giant octopus with a weight of 406 g was found to escape from an escape ring with a diameter of 30 mm or larger, and 592 g octopus, a weight similar to the octopus of the current minimum landing weight (600 g), escaped from an escape ring with a diameter of larger than 40 mm. An individual weight with 406 g becomes 39 mm when converted from a diameter of 25 mm circular escape vent; that is, the circumference to the inner diameter of the mesh. It can be inferred that the converted mesh size of 39 mm cannot escape. Logistic regression analysis was performed using a generalized linear model (GLM) to investigate the correlation between the ratio of escape ring size/Mantle diameter (R/MD) and the escape rate. As a result, it was found that there was a significant correlation between the R/MD ratio and the escape rate and that the higher the R/MD ratio, the greater the escape rate. As a result of logistic regression analysis, the R/MD value was denoted 0.520 with the 50% escape rate. In addition, it can be estimated to be about 50 mm when converted to the mesh size. Therefore, in this study, the diameter of the escape ring and the size of the escape possible of the octopus were experimentally considered. It was found that there was a significant correlation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.3
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• pp.190-197
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• 2019

This study investigated the luring effect of the sardine bait, which is used to catch octopus with pot, as the preliminary study for the development of alternative bait for octopus pot. The soaking time for bait was divided into "5 days or less" and "11 days or longer" The number of times octopus entered the pot with bait and the empty pot was investigated under dark adaptation and light adaptation processes and the distribution of tank section was investigated under light adaptation process. The case of "11 days or longer" sardine soaking time showed higher rate of distribution in the section of pot with bait compared to the case of "5 days or less" In the case of "5 days or less" soaking time, the number of times the octopus entered the pot with bait was similar to that it entered the pot without it even during dark adaptation and light adaptation. However, in the case of "11 days or longer", the octopus entered the pot with bait more quickly than the pot without bait and more frequently during dark adaptation hours. There were cases where the octopus did not enter any pot. In the case of "5 days or less", with less decomposition of baits, the octopus entered the empty pot more during light adaptation process, and it appeared that the pot was used as a hideout.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.3
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• pp.270-276
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• 2010

This study estimated the heavy metal concentrations in octopus (Octopus minor) and conducted a food safety assessment of octopus. Octopus, a benthic cephalopod, was collected from the Seosan intertidal zone on the west coast of Korea. The samples were digested with acids, and then the cadmium (Cd), copper (Cu), and zinc (Zn) contents were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The Cd, Cu, and Zn range of concentrations in octopus were 0.06-19 (mean 5.8), 44-1,463 (mean 354.8), and 76-929 (mean 247.9) mg/kg on a dry weight basis, respectively. The concentrations of heavy metals were higher in the internal organs than in the mantle. Of the three heavy metals, copper had the highest concentrations in the internal organs because of the existence of hemocyanin bound with copper in octopus blood, whereas zinc had the highest concentrations in the mantle. No relationship between the concentration of heavy metals and biological parameters (length, weight, and sex) was found. The ratios (I/M) of the heavy metal concentrations in internal organs and mantle were highest for cadmium, although cadmium had much lower concentrations in the internal organs compared with copper and zinc. Considering the provisional tolerable weekly intake (PTWI) of the three heavy metals and the average intake of octopus per day, all three elements should have no adverse effects on humans.