Toshiharu Kakihara

Three‐dimensional underwater shape measurement of tuna longline using ultrasonic positioning system and ORBCOMM buoy

The installation depth of the hook in longline fishing gear has previously been measured with micro depth loggers. Research that assumes the catenary shape of longline fishing gear by a simulation based on these data has been done. However, it was not known whether the branch line was tangled with the main line or flowed with the current. In this research, an ultrasonic positioning system generally used to investigate the underwater behavior of marine organisms, and a buoy with a communications satellite, have been used, and the 3-dimensional underwater shape of tuna longline fishing gear was measured. It was possible to monitor changes in fishing gear in real time. The possibility of high precision measurement was suggested with future technical improvement.

Short-range homing in a site-specific fish: search and directed movements

SUMMARY Sedentary and territorial rockfish of the genus Sebastes exhibit distinctive homing ability and can travel back to an original location after displacements of metres or even kilometres. However, little is known about the behavioural and sensory mechanisms involved in homing. Although our previous study demonstrated that nocturnal black rockfish Sebastes cheni predominantly use their olfactory sense for homing from an unfamiliar area, the possibility of using landmarks in a familiar area cannot be discounted; i.e. site-specific fish are likely to use three-dimensional spatial memory for navigation and orientation. Using high-resolution acoustic telemetry, we investigated whether S. cheni exhibit distinctive homing paths. Results show that all of the eight rockfish increased their effort within a small area of an unfamiliar region around the release site just after displacement, suggesting that the rockfish probably searched for the homeward direction. The rockfish showed the search movement in the upstream and/or downstream direction, which did not lead home. Finally, after returning to their familiar area, the rockfish exhibited more directed movements with faster speeds at a shallower depth, which was similar to the depth utilised in daily life as well as that of the fish capture.

Development of automatic system for monitoring fishing effort in conger-eel tube fishery using radio frequency identification and global positioning system

In this study, we developed a new automatic system, comprised of a radio frequency identification (RFID) system and global positioning system (GPS), for monitoring fishing effort, and effectiveness of effort, in fisheries using many pieces of fishing gear, such as hooks of longlines. The outline of this system is as follows. A single RFID tag with an identification (ID) number is attached to each piece of fishing gear. The RFID tag on the fishing gear passes the antenna of the RFID reader before being shot into the sea and after being hauled up from the sea. Data on the time and geographic location are measured by the GPS and recorded along with the ID number in a personal computer (PC). When a fish is caught, it is brought close to the fish-sorting table. Then, the second antenna of the RFID reader set at the side checks for a catch in the gear. The advantage of this system is that the fishing operation data can be collected without interfering with the fishermen’s usual work. The prototype of the system was tested at a conger-eel tube fishery in Tokyo Bay and was able to record data on the time, the location and the catch of individual conger-eel tubes successfully.

Receiving Distance of the Stationary Ultrasonic Biotelemetry Receiver in the Temperate Ocean

The investigation by the ultrasonic biotelemetry currently performed in Asia is shallow ocean space where water temperature is high. Furthermore, there is also much underwater noise, such as Pistol shrimp (Alpheus lobidens), in this ocean space. Therefore, differing from the receiving range that a maker recommends is assumed. Then, the maximum detection distance of VR2 was measured in the tank. From that result, the simulation that shows the detection range of this receiver quantitatively was performed. Moreover, the receiving range was measured in real ocean space, and change by oceanic condition was verified. Consequently, receiving distance brought a result shorter than a makers simulation. Also, the receiving distance was sharply changed by wind and weather.

Development of The Tuna Fish Catch Information Management System using RFID and a Communications Satellite

We presents a new information management system to verify tuna fish chain-of-custody from fishing vessel to the market, which consists of a radio frequency identification (RFID) system, a personal computer (PC), and a low orbital communications satellite (ORBCOMM) system. An RFID tag implanted into tuna fish body records fishing condition data, i.e., fishing time and position (latitude & longitude), vessel name, course and ground speed, and biological data of caught fish, i.e., species name, sex, and body length and weight. Data in the RFID tag are readable and rewritable through the RFID reader antenna without the need for direct contact with the object. The same data and the RFID tag ID number are simultaneously transmitted to an information control base through the ORBCOMM system. Managers of tuna fisheries and fish markets can read the data from the RFID tag in the fish body, and request for data verification from the data storage center over the Internet.

Construction of automatic fishery investigation system using GPS and RFID

We tried to develop a new automatic fishery investigation system comprising an RFID system and DGPS. This new system will be able to obtain a detailed fishery operation data, such as the fishing gear positions and fish caught at each point. The greatest merit of the new system is that fishing operation data can be collected without disturbing the usual operation. The reason to develop this system was that it relieve the investigation cost which were hands, expenditures and times. As the latest global trend, marine resources must be properly managed based on the total allowable catch (TAC) and total allowable effort (TAE), the necessity for fishing investigation will increase. The new automatic fishery investigation system will repay to the needs

Monitoring behavioral characteristics of the rockfish Sebastescheni inhabitinga seawall using LBL acoustic positioning system

Many members of the genus Sebastes exhibit homing behavior. Specifically, these species will return to the site where they have been captured after being released. In addition, Sebastes spp. exhibit site fidelity and diel migration in their home territories and foraging areas. The aim of this study was to use a high-precision ultrasonic biotelemetry system to accurately clarify the horizontal distribution patterns and the diurnal vertical movements of Sebastescheni inhabiting a seawall. Field experiments were conducted in Uraga Bay, Japan. The small bay is enclosed by seawalls and the sea floor of the area is smooth and approximately 10m deep. In 2011, experimental fish was captured using a hook and line and a transmitter with built-in a depth sensor was implanted into the peritoneal cavity of each fish. To reduce anomalous readings, the locality data were filtered using swimming speed, HDOP and excluded landing. Movement patterns were then monitored using a radio-linked acoustic positioning system after release at a site 40 m distant from the capture site. Tagged fish were observed to return to the site where they were captured, remaining in a relatively small area for the duration of the monitoring period. Tagged fish utilized three core areas in their home range, one was used during the day and the others were used between sunset and sunrise. Tagged fish remained at approximately 5m below the surface during the daytime, exhibiting more extensive vertical movements at night.

Development of a digital 3‐D SBL underwater positioning system combined with GNSS compass

A highly digitized underwater positioning system using the SBL method was developed. This system can measure highly accurate three‐dimensional positions of marine organisms equipped with an ultrasonic transmitter (pinger). This system is combined with a GNSS (GPS) compass that measures the bearing, the location (latitude and longitude), and the commotion (rolling angle and pitching angle) of a boat or a buoy. Then the pinger positions are compensated for the commotion and are translated into the underwater absolute positions. The four arbitrary frequencies of the pingers are received by four wideband hydrophones. The received signals are immediately AD converted in high speed and processed by the quadrature detection and the digital filtering with a bandwidth of 3 kHz using FPGA. Finally, the receiving time differences are measured by the cross correlation, realizing a resolution of 0.01 ms. A position measurement experiment was performed in a water tank (length 15 m, width 10 m, depth 10 m), changing the...