We analyzed heartbeat variability over time to quantify the physical load on swimming carp. First, heart rates before and after forced swimming were calculated from R-R intervals as an estimate of metabolic rate. Heartbeat intervals were continuously measured, and an autoregressive (AR) model was used with the interval data of heartbeat to express the degree of physical exhaustion and the recovery after exercise. A new parameter ARAV (autoregressive absolute variability), indicating heartbeat variability was defined by the parameters of the AR model. ARAV indicates both regularity and fluctuation of the heartbeat variability. Variable intervals gave relatively high ARAV. In contrast, stable heartbeat intervals corresponded to small ARAV. After moderate exercise, heart rates increased, and recovered almost completely after 60 minutes resting from cessation of forced swimming ; ARAV was relatively high during and after swimmmg. But after exhausting exercise, ARAV was reduced to almost zero. Both heart rate and ARAV were quantitative indicators of the physical load on fish.

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In order to observe of fish behavior to the set net, a radio transmission system for underwater video image was constructed and tested. This system consists of a transmitting station on the sea and a receiving station on the land. The transmitting station is composed of an underwater video camera, a video transmitter, a transmitting antema, lead-acid batteries, a cellular phone and a sound sensor for remote control of power supply. The underwater video image is transmitted to the receiving station with microwave of l.2 GHz. The receiving station is composed of a receiving antenna, a video receiver, a monitor and a VCR. The maximum transmission distance of the system was measured with about 7 km on the sea. The test run of the radio transmission system for underwater video image was conducted on the set net fishing ground in Tateyama Bay, Chiba Prefecture. The underwater video camera was installed in front of a funnel net to observe the fish behavior to the final trap of the set net. The transmitting station was moored near the final trap and the receiving station was set up in the Banda Marine Laboratory of Tokyo University of Fisheries where is l.5 km away from the set net. The test run lasted for 23 days in November, 2002. A total of 60 hours of the underwater video image were recorded and the fish behavior of 18 species were observed clearly during the test run. The inshore fish such as rudderfish Kyphosus vaigiensis, filefish Stephanolepis cirrhifer and blackfish Girella punctata frequently swam in and out the final trap through the funnel net. In contrast, yellowtail Seriola quinqueradiata did not escape from the final trap except for only one fish.

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Construction of artificial habitats has recently received attention as a technique for environmental remediation. In order to collect fundamental information that is required to develop efficient artificial habitats for remediation, an artificial habitat with experimental units (including plates of various densities), was set-up on the sea floor of the shore of Awaji Island, Japan. We observed the transition in the composition and biomass of the benthic community that inhabited the artificial habitat over three years. The artificial habitat was inhabited by 85 sessile and 218 mobile species. The number of species and biomass differed among the experimental units. Initially, the number of species was large ; and the biomass per surface area of the plates increased as the density of the plates decreased. The temporal changes in the biomass of the species were classified into four pattems, namely 'initial increase', 'later increase' , 'seasonal fluctuation' and 'irregular fluctuation'. Although the composition of the benthic communities that formed on the experimental units differed in the early stage, the proportion of large and camivorous species was high and the communities were similar in every experimental unit by the end of the experiment. We concluded that the climax community was hardly affected by the density or surface area of the plates in the artificial habitat within the context of the experiment.

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'NaLA', a system for detemining fishing net configuration and loading, has being developed for general, practical use with computer-aided fishing net design systems. This study tested the validity and accuracy of the simulation model through actual flume tank tests, and compares the results of the trawl simulation software DynamiT with those of NaLA to evaluate the accuracy and perfomance of NaLA. Close agreement between experimental and theoretical values was obtained for net shape configuration and tension loads. NaLA can determine the equilibrium state of the net configuration at an early stage, while the DynamiT mesh bars and towing lines bend and the net shape is unstable when the loading is of the order of kilograms, although the reason for this is not clear. Therefore, the calculations used in NaLA are more appropriate for general and practical applications.

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The buoy built-in GPS receiver for ORBCOMM system was developed recently. The ORBCOMM system is a kind of remote monitoring system using the communication satellite. Using this system, the drifting position of buoy is able to be monitored on real time mostly. But the system performance is not evaluated sufficiently in actual sea condition. In this paper, we explained the concept of this new satellite monitoring system, and the results of verification experiments on positioning accuracy and GPS data communication delay time conducted at sea. And, a proposal of a small single GPS receiver added to the buoy in order to improve the positionig accuracy is made and the experimental results is also discussed.

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The performance of biodegradable plastics in seawater at various locations was examined. The seawater was sampled in the pier of Tokyo University of Fisheries, the mouth of Tama river, the mouth of Edo river, the mouth of Kyuedo river, Sagami bay and the offing in Boso peninsula. In this study, we used two samples of biodegradable plastics, polycaprolactone (PCL), and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) [p (3HB/V)]. The biodegradability of their films in seawater was assessed by monitoring the time-dependent changes in the biochemical oxygen demand (BOD). The films were rapidly degraded in seawater sampled in Tokyo bay and BOD-biodegradability of their films was 42 and 92% for 7 and 23days respectively. BOD-biodegradability of films in seawater sampled in other area was Iower than that sampled in Tokyo bay. The study using the scaming electron microscope showed the films decomposed by the microorganism. The PCL-degrading microorganisms were isolated from the seawater and designated R-1, R-2 and R-3. Physiological and phylogenetic characters of these microorganisms were examined. These results show that strain R-1 was identified as Pseudomonas studomons, and strains R-2 and R-3 belong to the genus Pseudomonas. Biodegradation of PCL monofilament fiber by isolated bacteria, strain R-1 was investigated. Tensile strength of PCL monofilament was rapidly reduced to 50% for 2 days.

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In Japan, the accident rate among fishery workers is eight times higher than that for workers in all other industries. The trawl fishery, which had one of the highest rates of work accidents in the fishing industry, was chosen as the subject of the present study. The ergonomic conditions of the working environment onboard trawlers were examined by analyzing the motion of workers. To evaluate the relative position between the worker and fishing implements, we analyzed the moving line and the working position during fishing operations. The posture of workers was measured to calculate a value for the pain index number. The moving line of the worker walking on the net was observed, and it became clear that the range of movement for the workers was wide. Walking on the net is a dangerous behavior under heavy rolling motion because workers are easily thrown overboard. Various unnatural postures related to 'inclination' were observed during fish selection and putting fish into boxes. The working posture during selection was evaluated by the pain index number. For workers on an 80-GT trawler, the pain index number attained five because fish was placed directly on the floor. If the trawler was equipped with a belt conveyer, the worker would select the fish in a standing position. We proposed an index to reduce work accidents at the fishery.

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A earth monitoring system which consists of a zero-phase-sequence current transformer (ZCT), current relay (OCG) and three condensers was constructed in order to detect the accident point for the lower ground fault resistance on the electrical machinery, apparatus and lines. It was installed on a a.c. 100V feeder panel in the research and training vessel Umitaka maru, while measurement was carried out to evaluate the performance of the device. As a result, the following issues were clarified. 100mA in the ground fault current was measured by this device, and then the alam of a 'lower ground fault resistance' was confimed on the data-logger when the ground fault resistance was Iowered to 0.6kΩ. In this case, the decrease of 20 mA in the ground fault current was confirmed when the condenser was not comected to the feeder. However, the detection of the lower ground fault resistance while not comected to the condenser was still possible.

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A prevention apparatus of dissolved oxygen deficiency in closed basin such as pond, lake and dam is proposed, and the possibility of the practical application of this equipment is indicated. This equipment is consisted of a vertical rotating shaft, eight radiation partition plates and two parallel disks. The horizontal radiation jet is formed by rotating the disks at the near water surface and is induced the vertical circulation flow in the cIosed basin. As the result, the dissoIved oxygen deficiency at the bottom will be restrained.

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