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The International Organization for Standardization has standardized "fine bubble" for bubbles less than 100 µm diameter. Even when the same amount of gas turns into bubbles, due to its fineness, the number of fine bubbles is much larger than that of easily visible cm-size bubbles. As a result, the total bubble surface area is expanded, and the chemical reaction efficiency at the gas-liquid interface is dramatically improved. If air is contained within, it will increase the amount of dissolved oxygen in the water. For this reason, the use of fine bubbles has been growing in the agriculture and fisheries industries, where dissolved oxygen is essential. For example, it is used for irrigation in the agricultural industry and for densification processes in the fishery industry. In each case, it is utilized to solve problems in the field. [ABSTRACT FROM AUTHOR]

Despite the growing importance of open innovation in agriculture, forestry, and fisheries, few academic studies have analyzed its current status. This study analyzed the current status of open innovation in the field of agriculture, forestry, and fisheries using data reported on the activities of the Field for Knowledge Integration and Innovation, a public-private partnership council established by the Ministry of Agriculture, Forestry, and Fisheries in 2016. The analysis revealed that the platforms are formed by a wide range of research fields, and that the proportion of members from other fields may influence the research approach of each platform. [ABSTRACT FROM AUTHOR]

In Zimbabwe, which has experienced white settler colonialism, racial inequalities over resources have historically been shaped. Therefore, it is essential to consider the political and economic context of the commercial kapenta fishery, the focus of this paper. This paper aims to identify the politics of access to kapenta fishery and issues related to resource use, and discuss them from the perspective of Political Ecology. Kapenta fishery and the Lake Kariba where it developed were rooted in the historical context of settler colonialism. Racial exclusivity existed in access to fishing permit before independence. After independence, patron- client relationships functioned in access to fishing permit among black operators. However, the changes implemented in conjunction with land reform, with the redistribution of permits and the introduction of a lease system, the actors involved in kapenta fishing became more diverse and, in some cases, more informal. The operators identified the decrease in catches, trading on the lake and fishing in prohibited areas as challenges. These violations were the result of a combination of institutional changes and practices by actors at various scales. Understanding the complexity of environmental- human relationships, as this paper demonstrates, is important as a foundation for discussions of resource management. [ABSTRACT FROM AUTHOR]

Kenzo Araki (1907–1991) was a fisherman, who lived at Kutsugata, western Rishiri Island, since 1928. He managed both set-net fishing of herring at spring and various fisheries using a powered fishing boat except for bottom trawling fishing. After his retirement from the front line of fishing, he tried to compile a history of Rishiri Island, especially a history of fishing on this island. His various materials, e.g. books, newsletters, memorial magazines, reports, photos, etc., which were collected by himself for his historical interest when he was alive, have been unregistered in the custody of Rishiri Town Museum since 1992. This is the checklist of his collection, the Araki-Kenzo Collection (KAr), and the number of materials amounts to 7,103 in Dec. 2021. There are many sources concerning Rishiri Island in a wide range of fields. [ABSTRACT FROM AUTHOR]

We investigated the occurrences of Noctiluca scintillans in the coastal waters of Harima-Nada, the Seto Inland Sea, using the red tide data set. These data concerned red tide occurrences that were reported in an annual report entitled “Red tides in the Seto Inland Sea” which was published by the Seto Inland Sea Fisheries Coordination Office of the Fisheries Agency, Ministry of Agriculture, Forestry and Fisheries of Japan. These data were imported into a geographic information system, and red tide areas were calculated. During the 26 years from 1979 to 2004, in the Seto Inland Sea, eutrophication improved, nutrient concentrations in seawater decreased dramatically, and the number of red tide occurrences excluding those concerning Noctiluca scintillans, decreased. However, the number of occurrences, area, and durations of Noctiluca scintillans red tides did not decrease. The ratio of Noctiluca scintillans red tides to total red tides for an average red tide index, which permits the assessment of spatial and temporal scales, was 54%. This was higher than that of the number of occurrences (36%). This indicates the importance of N. scintillans as a red tide organism. [ABSTRACT FROM AUTHOR]

“The Colloquium on Oceanography” was initiated by a chief scientist, Michitaka Uda, of the Imperial Fisheries Institute, in April, 1932, to introduce papers, present oneʼs study results, and promote information exchange between members. Bi-monthly meetings, which were held on Thursdays at the Imperial Fisheries Institute, eventually led to 172 meetings and 506 lectures by 80 members until February, 1942. The cooperation between members and fervor for oceanography resulted in the proposal to create “the Oceanographic Society of Japan” in 1936. However, the proposal of “Kaiyo-Gakkai,” which had been previously presented at the Imperial Marine Observatory in Kobe, failed in the first half of 1937. The mutual consultation between “Kaiyo-Gakkai” and “the Colloquium on Oceanography” succeeded in building a committee on “Standard Sea Water” in December, 1939, and subsequently, “the Oceanographic Society of Japan” was established on January 28, 1941. In this study, the authors describe the examination of the proposal, contents, and details that led of the foundation of “the Oceanographic Society of Japan,” including participation by some scientists [ABSTRACT FROM AUTHOR]

“The Colloquium on Oceanography” was initiated by a chief scientist, Michitaka Uda, of the Imperial Fisheries Institute, in April, 1932, to introduce papers, present one?s study results, and promote information exchange between members. Bi-monthly meetings, which were held on Thursdays at the Imperial Fisheries Institute, eventually led to 172 meetings and 506 lec¬tures by 80 members until February, 1942. The cooperation between members and fervor for oceanography resulted in the proposal to create “the Oceanographic Society of Japan” in 1936. However, the proposal of “Kaiyo-Gakkai,” which had been previously presented at the Imperi¬al Marine Observatory in Kobe, failed in the first half of 1937. The mutual consultation be¬tween “Kaiyo-Gakkai” and “the Colloquium on Oceanography” succeeded in building a com¬mittee on “Standard Sea Water” in December, 1939, and subsequently, “the Oceanographic Society of Japan” was established on January 28, 1941. In this study, the authors describe the examination of the proposal, contents, and details that led of the foundation of “the Oceano-graphic Society of Japan,” including participation by some scientists. [ABSTRACT FROM AUTHOR]

The total mercury content in 112 fishery products, purchased from Osaka city during 2013-2018, was measured using a heating vaporization mercury analyzer. The average total mercury content in all tuna processed products was found out to be 0.115 μg/g (median=0.070 μg/g). Notably, albacore tuna exhibited the highest mercury content with an average concentration of 0.301 μg/g (median=0.296 μg/g). The total mercury concentration of the fishery products, except processed tuna and Kezuribushi (comprising shavings of dried and smoked mackerel, sardine, as well as horse mackerel), was generally low (<0.1 μg/g).The provisional tolerable weekly intake (PTWI) for mercury as set by the Joint FAO/WHO Expert Committee on Food Additives is 4.0 μg/kg body weight/week. On an average, for Japanese diet, the total weekly mercury intake from fishery products for a person weighing 50 kg was estimated to be 0.13 μg/kg body weight/week, which was 3.3% of the PTWI. These values indicate that it was not a problem to consume fishery products normally. However, albacore tuna cans have a relatively high total mercury concentration; thus, pregnant women consuming them daily may exceed the tolerable weekly intake of methylmercury (2 μg/kg body weight/week) as set by the Food Safety Commission of Japan.

In this study, we developed an analytical method for simultaneous determination of 14 quinolones and 4 tetracyclines in livestock and fishery products using LC-MS/MS. The analytes were extracted from food samples with citrate buffer (containing EDTA)-methanol-acetonitrile (3 : 1 : 1, v/v/v) in the presence of n-hexane, and the extract was purified with an Oasis PRiME HLB cartridge column. It was suggested that this analytical method can also extract analytes from solid samples containing fat by using n-hexane. In addition, using methanol-acetonitrile (3 : 7, v/v) containing 0.1 vol% formic acid as an eluent from the cartridge column, the purification effect could be improved, while minimizing the impairment of the recovery rate. As a result of the validation using six types of food samples, trueness (accuracy) was 70.6%-113.8%, the RSD of repeatability was 9.0% or less, and the RSD of within-laboratory reproducibility was 15.5% or less. Using this approach, the standard values mentioned in the Japanese guideline were successfully met.

A rapid, easy, versatile, simultaneous analytical method based on three-layer extraction and LC-MS/MS was developed for the determination of residual veterinary drugs in livestock and fishery products. In this method, degreasing with n-hexane, partitioning into acetonitrile, and purification by the salting-out effect were simultaneously performed after extraction with acetone aq. It allowed to prepare a test solution without concentrating, transferring, and purification using solid column. Recoveries of quinolones were improved by adjusting acid concentration and adding EDTA-2Na・2H 2 O. As a result, 62 analytes for cattle muscle, 63 analytes for cattle fat, 62 analytes for eel, and 65 analytes for salmon met the management criteria of the guideline for validity assessment (Ministry of Health, Labour and Welfare in Japan). Thus, the present method could be useful for a rapid determination of residual veterinary drugs in livestock and fishery products.

A sensitive and reliable method for the simultaneous determination of four nitroimidazoles (ipronidazole (IPZ), dimetridazole (DMZ), metronidazole (MNZ) and ronidazole (RNZ)) and three metabolites (IPZ-OH, MNZ-OH and 2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI)) in livestock and fishery products was developed. The analytes were extracted from samples with acetone containing acetic acid. The crude extracts were defatted by liquid-liquid partition using acetonitrile and n-hexane followed by solid-phase extraction using a cartridge column packed with divinylbenzene-N-vinylpyrolidone copolymer bearing sulfo groups. The analytes in the eluate from the cartridge column were extracted with ethyl acetate after addition of ammonium sulfate. The solvent was removed from the extract, and the residue was dissolved in 0.1 vol% formic acid. The HPLC separation was performed on a C18 column with a gradient formed from water containing 0.1 vol% formic acid and acetonitrile containing 0.1 vol% formic acid. For detection of the analytes, tandem mass spectrometry with positive ion electrospray ionization was used. The recovery tests were performed on 10 livestock and fishery products. The truenesse ranged from 74.6 to 111.1%, with repeatability of 0.5-8.3 RSD% for the entire procedure. The limit of quantification was 0.0001 mg/kg for IPZ, IPZ-OH, MNZ and MNZ-OH, and 0.0002 mg/mg for DMZ, RNZ and HMMNI.

We report a Japanese breath-hold diver (Ama) who presented neurological disorders after diving. He repeated diving into 25-30 meters depth in the sea for 6 hours. After diving, he felt dizziness and unsteady gait. Neurological examination showed left quadrant hemianopia, bilateral limb ataxia and ataxic gait. Head CT revealed gas bubbles in the left parietal lobe. In CT scan on 3 days after onset, gas bubbles disappeared and low density areas were observed in the bilateral parietal lobes. Brain imaging (DWI, T(2)WI and FLAIR) demonstrated high intensity in the parieto-occipital lobes. Neither pulmonary barotrauma nor intracardiac shunt was detected. He was diagnosed as having neurological decompression illness and therefore underwent hyperbaric oxygen therapy. The pathogenesis of this case was considered to be microbubbles induced by decompression. The present case suggests that repetitive rapid surfacing from the deep sea causes neurological decompression illness even in the breath-hold diver.

Pulmonary tuberculosis among deep-sea fishermen was reported. Four pulmonary tuberculosis cases among fishing boat members engaged in deep-sea fishing were registered at the Kesennuma Health Center during three years period from 2000 to 2002. Crew engaging in deep-sea fishing live together in a narrow cabin with inadequate airconditioning for a long period of time, about 1 year. It is difficult to consult with a medical institution in an open sea. If a tuberculosis patient breaks out in a boat, the risk of transmission of tuberculosis to other members is high. In boats of all four cases in this report, about 30 to 70 percent of crew were Indonesian. Indonesia is one of the high burden countries of tuberculosis in the world. The Japanese fishing boat members have received the medical checkup every year. Indonesians have also received the pre-employment medical checkup, however, the improvement in the quality of this medical checkup is required.

The purpose of this study was to detect factors affecting lumbar bone mineral density (BMD) of general inhabitants in a rural community. A cohort consisting of 2261 inhabitants aged 40-79 years was set up based on the resident registration in Taiji town, Wakayama Prefecture in 1992. Fifty men and 50 women in each of four age strata (40-49, 50-59, 60-69, 70-79), totaling 400 inhabitants, were selected randomly. After completion of a questionnaire by an interviewer, items about physical characteristics such as height, body weight, wrist length and grip power were measured. Examination of BMD of the lumbar spine and proximal femur by dual energy X-ray absorptiometry was performed. Correlation coefficients between BMDs and values of physical characteristics were determined. Lumbar BMD was examined to determine whether the following factors were positive or negative: past history, alcohol consumption, smoking habit, dietary habit, exercise, and in addition, pregnancy times and menstrual status for women. Among the values of physical characteristics, body weight was the most closely correlated with lumbar BMD. The items that showed significantly high values as factors affecting lumbar BMD were a past history of diabetes mellitus (men and women in their 70s), and exercise (men in their 50s and women in their 40s). Regarding pregnancy times and menstruation, BMD in women with a history of childbirth was significantly higher than that in those without the history among the women in their 70s. Although the BMD in the women with lactation was significantly lower than that in those without it among the women in their 40s, there was no difference in BMD between the women with and without the history who were 50 years old or over. The effect of menstrual status was investigated according to years after menopause in the women in their 50s. BMD was significantly lower in the women with ar least six years after menopause than in those within five years.

To establish reference values for bone mineral density (BMD), a population survey was carried out in a fishing community in Wakayama Prefecture. The BMD measurements of the lumbar spine (L2-L4) and proximal femur (femoral neck, trochanter and Ward's triangle area) were performed by sex and age, using dual-energy X-ray absorptiometry. Four hundred subjects, aged 40 to 79 years, were recruited randomly to give 50 persons in each of eight age-sex strata from a list of 2,261 residents (1,028 men and 1,233 women) living in a fishing village. The validity of sampling methods was assessed using a questionnaire about lifestyle factors, which was used for all residents aged from 40 to 79 years in the baseline survey. There were no significant differences between the subjects for BMD measurements and all the residents of the community in the frequencies of past history of diseases, healthy habits, food intakes, and rates of smoking, alcohol drinking, coffee and green tea consumption. These findings suggested that the present study population could be considered representative of samples obtained from the entire population in the fishing community. The results of BMD measurements in these subjects, who were selected at random, showed that except for a slightly high BMD of the lumbar spine in men in their 60's, the mean BMD of the lumbar spine and the three proximal segments of the femur decreased with increasing age in both sexes.

This study aimed at descriptive understanding of traditional methods involved in locating fishing points and navigating to them in the sea, and investigate associated cognitive activities. Participant observations and interviews were conducted for more than 30 fishermen who employed hand-line or long-line fishing methods near Toyoshima Island, Hiroshima Prefecture. The main findings were: (1) Fishermen readily perceived environmental cues when locating fishing points, which enabled them to navigate to a correct point on the sea. (2) Their memory of fishing points was not verbal, but visual, directly tied to the cue perception, and was constantly renewed during fishing activities. (3) They grasped configurations of various natural conditions (e.g., swiftness of the tide, surface structure of the sea bottom) through tactile information from the fishing line, and comprehended their surroundings with accumulated knowledge and inductive inferences. And (4) their cognitive processes of perception, memory, and understanding were functionally coordinated in the series of fishing work.

More than thirty years have elapsed since the major outbreak of Minamata disease. The purpose of this study is to examine the current health conditions among fishermen living along the coastal area of Yatsushiro Sea which received high exposure to methylmercury contamination. From 1988 to 1990 an interview survey was conducted on a random sample of 215 fishermen in two adjoining areas classified as contaminated: Minamata City of Kumamoto Prefecture and Izumi City of Kagoshima Prefecture. Completed responses were collected from 181 (129 males and 52 females). Health conditions were measured by four indicators: activities of daily living, presence of chronic diseases, subjective symptoms, and depressive symptoms. The associations between each health indicator and estimated intake levels of fish and/or shellfish during the heavy contamination period were examined. Residents in areas designated as contaminated can be categorized into three groups: 1) persons who are officially recognized as patients with Minamata disease, 2) persons applying for recognition as having Minamata disease but who have not been officially recognized, and 3) persons who have not applied for official recognition. In the analysis this recognition-related status was used as one of the controlling factors. Findings may be summarized as follows: 1. In both areas, a significant relationship was observed between subjective symptoms and estimated fish intake levels after controlling for sex and age. Judging from subjective symptoms, it appeared that the health level of recognized patients was lowest among the three recognition-related groups; and the health level of non-recognized persons was lower than that of the non-applicants. 2. Among Minamata City fishermen, the significant effect of fish intake levels on subjective symptoms disappeared after controlling for sex, age and recognition-related status. On the other hand, among Izumi City fishermen, a significant relationship between subjective symptoms and fish intake levels still remained by the same analysis. 3. The mental health level of the non-recognized as well as of recognized patients was comparatively lower than that of the non-applicant. However, within the limits of this study, the association between mental health and fish intake levels was not clear.

We report a comparative study of the Standardized Mortality Ratio (SMR) for circulatory system diseases and diet in a rural town and a fishing town in Kyoto Prefecture. SMR was assessed during the 5-year period from 1983 through 1987, and compared with the standard age- and sex-adjusted demographic and mortality statistics compiled by the National Census Bureau of Japan in 1985. A food frequency questionnaire in which the respondents evaluated their food consumption during the previous 1-year period was used to assess diet. The questionnaire was administered during February 1989 in the rural town and during February 1990 in the fishing town. In comparison with the standard statistics, SMR was higher in the rural town and lower in the fishing town. The inhabitants of the fishing town more frequently consumed low-fat and low-sodium foods, such as fish, potatoes, tofu, and green, yellow and other vegetables, and less frequently consumed high-fat and high-sodium foods, such as meat, fried food, pickles, than did the inhabitants of the rural town. The residents of the fishing town also consumed a greater variety of foods in one week. The two towns differ in geography and economic structure, and their inhabitants have different life-styles and eating habits. The lower SMR for circulatory system diseases in the fishing town may be related to the greater consumption of fish and vegetables with lower meat and salt intake, as well as the balanced of diet.

Based on our previous health survey among Ishigaki fishermen in 1979, this study aimed at clarifying the relations of their work histories to physical characteristics, physiological functions, blood conditions and hearing levels. Medical examination was conducted in 1987 on 118 fishermen inclusive of 33 followed-up fishermen, and in 1989 noise-level and noise-induced temporary threshold shift of hearing was measured for different fishing methods. The results were as follows; 1) Fishing history was not specifically associated with any physical characteristics. 2) High HDL cholesterol, which was observed among divers using diving apparatus, was considered to be a survival effect for divers, since HDL cholesterol is amplified by intensive muscle work. 3) Abnormalities of ECG except for a high R wave were notably observed among the divers, who once changed from unassisted diving to diving with apparatus and then to fishing lines. The main reason for switching jobs was claimed to be caisson disease, and it was suggested that diving with apparatus was related to a high risk of health hazards in the central nervous system and/or respiro-circulatory system. 4) Acoustic acuity greatly declined with aging, and which was commonly observed in groups with different work histories. By way of explanation, exposure to ship engine sounds during daily travelling was the most likely cause. It was also revealed that several hours' exposure to the engine sounds was needed to detect a temporary threshold shift of hearing before and after work.

Dietary and serum fatty acid composition and their relations were investigated in men aged 40-59 years from six geographical and occupational populations: fishermen, three farming populations, urban clerical and manual workers. 1. Mean dietary intake of saturated, monounsaturated and polyunsaturated fatty acids were higher in urban workers than in the other populations. Mean dietary intake of omega 3 polyunsaturated fatty acids was higher in fisherman than in other populations. There were no differences in dietary compositions of saturated, monounsaturated and polyunsaturated fatty acids among six populations. However, the proportion of dietary omega 3 polyunsaturated fatty acids to total fatty acids varied: 10% for fishermen, 7-8% for farming populations and 6% for urban workers. 2. There were no differences in serum compositions of saturated, monounsaturated and polyunsaturated fatty acids among six populations. However, the proportion of serum omega 3 polyunsaturated fatty acids to total fatty acids varied: 15% for fishermen, 9-10% for farming populations and 8-9% for urban workers. 3. Significant associations were observed between population means of the proportion of dietary and serum polyunsaturated fatty acids. Within each population, individual dietary intake of omega 3 polyunsaturated fatty acids was significantly associated with the proportion of serum omega 3 polyunsaturated fatty acids. Significant associations were also obtained for omega 6 polyunsaturated fatty acids. 4. Fishermen showed a higher population means of dietary and serum omega 3 polyunsaturated fatty acids and a higher incidence rate of cerebral infarction compared with the other populations. This result did not support the hypothesis that dietary and serum omega 3 polyunsaturated fatty acids contribute to prevent cerebral infarction.

Among spiny lobster fishermen on the Pacific coast of Miyazaki Prefecture, the authors found two cases with bronchial asthma due to occupational sensitization with red soft corals (Dendronephthytia nipponica). In this report are presented these two cases, and the results of further investigation from allergic viewpoint on 72 subjects of the same occupation. Among these fishermen, such symptoms as sneezing, nasal discharge, cough, asthmatic attacks, conjunctival hyperamia, and dermatitis on removal of catches (red soft corals) from a dragnet were seen during spiny lobster fishing season, from September to mid-April. These symptoms did not develop on days when no soft corals (marine coelenterate) were caught in the lobster net. From a survey conducted with questionnaires all subjects of fishermen had conjunctival and skin manifestations, 9% of them had bronchial asthma and 39% of them complained of symptoms of rhinitis on exposure to red soft corals. Intracutaneous test with red soft coral extract in the asthmatic fishermen showed strongly positive for immediate and delayed type reactions, whereas in ten asthmatics engaged in other occupation negative for delayed reaction and occasionally positive for immediate reaction. And in all of five healthy subjects the cutaneous reaction of both types were quite negative. These findings suggest that red soft corals are both allergenic and irritating to humans. The allergic reactions due to red soft corals are considered to be a kind of occupational allergy that has arisen from alterations in work condition.

A base-line survey was performed for 3,185 persons over 40 years of age in 1984 and 1985 in agricultural and piscatorial areas of Hokkaido with regards to their dietary habits and life style. Of them, 147 persons died prior to the recent follow-up survey of 1988. As a result of a case-control study of the dead with those of the followed-up group, a more frequent intake of instant noodles was indicated as significantly increasing the risk of death, even after adjusting for the health status at the base-line survey and other confounding variables (the adjusted relative risk = 1.44 per a frequency class, p = 0.049).

Six hundred and eighteen men and 993 women ranging in age from 30-69, living in Kamo Village, Shizuoka Prefecture, underwent baseline health examinations in 1964-1966. During the follow-up period of 20-years, 175 men and 170 women died. The most frequent cause of death was malignant neoplasms (57 men and 45 women), followed by stroke (47 men and 44 women) and heart disease (29 men and 37 women). The relationship of 22 cerebro-cardiovascular disease variables investigated in the baseline examination to stroke and heart disease mortalities, and, in addition, to cancer and all-cause mortalities were analyzed using Cox's proportional hazard model. In univariate analysis controlled for age and sex, systolic and diastolic blood pressures, albuminuria, hypertensive and sclerotic changes in fundus oculi, body mass index, atrial fibrillation, and use of antihypertensive drugs had significant positive relationships to stroke mortality. As for heart disease mortality, albuminuria, glucosuria, high R wave, and ST and/or T changes in ECG were positively and significantly related. Only Q.QS in ECG significantly correlated with cancer mortality. Variables showing significant relationship to all-cause mortality were systolic and diastolic blood pressures, albuminuria, glucosuria, hypertensive changes in fundus oculi, Q.QS, high R wave, ST and/or T changes, atrial fibrillation, use of antihypertensive drugs, and history of stroke. In multivariate analysis (step-wise) of all examination variables including age and sex, stroke mortality was significantly related to age, atrial fibrillation, use of antihypertensive drugs, and hypertensive changes in fundus oculi. Age, albuminuira, and ST changes in ECG were significantly related to heart disease mortality. Age, sex, and Q.QS in ECG were significantly related to cancer mortality. The relationship of age, sex, albuminuria, Q.QS, and ST changes in ECG to all-cause mortality was significant.

The intranasal pressure at the opening of the auditory tube was compared by Valsalva's method with that of normal adults under atmospheric pressure to find the auditory tubal function of divers often exposed to hyperbaric conditions. It was found that the mean auditory tube opening pressure was higher in professional divers than in normal adults who had never been exposed to hyperbaric pressure. There are two ways of accommodating human auditory tubal ventilation: active opening and passive opening--the former is predominant in adults, the latter in children. The function of professional divers resembles the child type. This finding suggested that they were frequently exposed to a hyperbaric environment, and their auditory tube might not be opened and closed with each swallowing movement under atmospheric pressure, or the auditory tube and the middle ear themselves have been changed into a condition whereby they no longer needed the opening with each swallowing movement might under atmospheric pressure. Moreover, divers take various postures while they are diving, and in rapid dive, they often take a head-down posture. It was obvious that the auditory tube opens less readily in the head-down position. This phenomenon appears to represent the effect of hydrostatic venous pressure in water.

Diving profiles of fishermen divers in the Izu Islands were investigated and recorded by DDR (Diving Data Recorder). Consumed air volume during diving work was also checked in each dive and the work load was measured by VO2 during diving. It was recognized that divers repeatedly experienced extreme descents and ascents, that were accompanied by increases of oxygen consumption. This suggested that the load of their work was far beyond that of sports divers. The particular diving method used, called the "Oikomi Gyoho method" is to repeatedly dive several times to catch fish. Each bottom (diving) time is rather short and the dept changes from deeper to shallower areas gradually. This profile is considered to be a safe diving method for the prevention of DCS (Decompression Sickness). However, stopping for decompression during ascent is sometimes required to prevent DCS according to analysis of the diving profiles. It is pointed out that the risk of DCS still remains with this diving method.