Takafumi Arimoto

Tokyo University of Marine Science and Technology · Department of Marine Biosciences

The effect of fatigue on swimming performance was examined by measuring the swimming endurance time and heart rate of the jack mackerel Trachurus japonicus [15.7 ± 0.8 cm fork length (FL), n = 15] during forced exercise in a flume tank at fixed swimming speeds of 4, 5 and 6 FL/s. Electrocardiographic (ECG) monitoring during the experimental process...

An electrophysiological approach on swimming performance for jack mackerel (Trachurus japonicus) was conducted for the purpose of understanding the capture process of mobile fishing gear. The physiological condition of jack mackerel (18.3±1.2 cm fork length (FL), n = 24) was simultaneously monitored using electrocardiography (ECG) and electromyogra...

Fish consumption will continue to increase worldwide with the global demand of healthy seafood, through the increasing trend of fisheries production, especially in developing countries. In order to understand the developmental trend of fisheries production in Asian countries, the yearly production per capita of capture fisheries and aquaculture was...

The heart rate of jack mackerel [16.5–21.2 cm fork length (FL), n = 24] was examined through forced swimming exercise in a flume tank by 10-min step-ups of speed levels in 1.5–6.0 FL/s range at different temperatures of 10, 15, and 22 °C. Electrocardiograph (ECG) monitoring was conducted by comparing the heartbeat pattern in still water without flo...

The muscle contraction time of fish can be the good index for swimming capability to estimate the maximum swimming speed, by defining the maximum tail beating performance. The muscle contraction time of jack mackerel, Thachurus japonicus (18.0 – 19.4 cm of fork length (FL), n = 15) was measured with newly developed portable systemand compared with...

The behavior of Japanese common squid Todarodes pacifcus in the laboratory tank was observed with an acoustic camera (DIDSON) under light and dark conditions to understand their behavioral response to light. To examine the effect of switching the light on and off observations were conducted under four different lighting patterns consisting of combi...

In the jigging fishery for neon flying squid Ommastrephes bartramii, the catch loss due to hooked squid falling off caused by tentacle breakage should be reduced. For this purpose, the jig motion was monitored with an acceleration data logger to examine the upward jig speed for the squid to be hooked by tentacles or other arms. Only the ratio of ho...

Swimming performance of jack mackerel Trachurus japonicus (18.2 ± 0.8 cm fork length (FL), n = 185) was examined in a flume tank by measuring the stride length at low and high tail beat frequencies with electromyogram monitoring and a muscle twitch experiment. Stride length was analyzed by monitoring the tail beat frequency according to the swimmin...

In squid jigging operations for neon flying squid (Ommastrephes bartramii), 30–40% of hooked squid are estimated to fall off (i.e., become detached) from the jigs during the drum-hauling process, caused by breakage/severance of the hooked tentacle(s). Reducing fall-off events can lead to higher productivity and more efficient use of the squid resou...

The retinal structure and visual acuity in Japanese flounderParalichthys olivaceus at different stages of development were examined by light microscopy. The resolving power of the retina, the visual axis and the best visual field were estimated based on the distribution of cone cells in the retina. The visual system of the larvae appears poorly dev...

Concern about the impact of fishing on ecosystems and fisheries production is increasing (1, 2). Strategies to reduce these impacts while addressing the growing need for food security (3) include increasing selectivity (1, 2): capturing species, sexes, and sizes in proportions that differ from their occurrence in the ecosystem. Increasing evidence...

The Japanese type of set-net, Otoshi-ami, was introduced to Thailand in 2003 with the aim of assessing its feasibility as a sustainable coastal fisheries management tool for the empowerment of coastal fishers’ communities. All preparations for constructing and installing the set-net in the coastal waters off Mae Rumpheung beach, Rayong Province, Th...

Codend selectivity for the jack mackerel Trachurus japonicus and the whitefin jack Kaiwarinus equula were evaluated based on data from trouser trawl experiments carried out in the East China Sea, using a test codend of 60 mm diamond mesh and a control codend made of minnow net with a square mesh of 9 mm bar length. Between-haul variations in parame...

The conventional selectivity paradigm is briefly reviewed and its performance examined from an ecosystem perspective. It is stressed that the overall (cumulative) selectivity of the harvest process in an ecosystem is the result of nested selection by fishers and fisheries of: (i) habitats; (ii) species assemblages; (iii) populations and (iv) indivi...

The heart rate of kuruma shrimp Marsupenaeus japonicus during exercise was examined in a flume tank based on swimming endurance trials in a speed range of 17.7-33.9 cm/s, and by electro-cardiogram (ECG) monitoring. With increased swimming speed, endurance time was shown to decrease, showing a sustained speed of 23.9 cm/s by swimming curve analysis....

The effect of temperature on the swimming performance of jack mackerel Trachurus japonicus was examined in a flume tank by measuring the swimming endurance time and heart rate. The lower swimming performance was observed at 10°C (the lowest temperature tested), manifesting as the shortest endurance time and the slowest maximum sustained speed. ECG...

Absract For the purpose to empower the coastal fishing community, it is important to formulate a development model for the sustainable resource management through the introduction of appropriate tools for the local fishers working together as the group. In Japan, the set-net fisheries have been traditionally controlled under the community-based man...

The species of flatheads, including Platycephalus bassensis (Cuvier, 1829) and Neoplatycephalus richardsoni (Castelnau, 1872), are common shallow-water (30–160 m depth) teleosts and a valuable component of Australia's largest commercial fishing sector. In this study the behavioural responses of these species to a demersal trawl towed at 1.29 m s−1...

To understand the mechanism of the behavioral response in the capture process of how fish recognize fishing gear and then how they can avoid the gear, the visual acuity of Pacific saury Cololabis saira was investigated by histological examination of the retina of individuals in the size range of 75–365 mm fork length (FL). The contour map of cone d...

Laboratory experiments were firstly conducted to determine the possibility of modification of the collapsible pot for blue swimming crab Portunus pelagicus by designing appropriate escape vents in terms of shape, position, and size to improve size selectivity by reducing the catch of immature crabs. In laboratory observations, nearly square-shaped...

The swimming performance of Platycephalus bassensis at steady speed was assessed with an emphasis on hydrodynamics. The minimum swimming speed to maintain hydrostatic equilibrium for P. bassensis of 0·271 m total length (LT) was calculated to be 1·06 LT s−1. At this speed, the required lift to support the mass of the fish was equivalent to 6·6% of...

The crayfish-shaped artificial bait for octopus drift line is manufactured, into which is made to insert ordinary bait. The effects of the artificial bait are confirmed through the analysis of octopus` behavior in the laboratory in comparison with the existing bait of pig-fat skin, and the investigation of the octopus catch on the sea, and in addit...

The behavioural response of the jack mackerel Trachurus japonicus when encountering a netting panel was shown to be influenced by swimming speed and the diagonal mesh-size ratio (vertical:horizontal).

The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bassensis) was assessed by video observation of fish swimming in a tank and measurement of muscle contraction time. Knowledge of the maximum swimming speed is important because it influences the ability or otherwise of fish to escape from various parts of...

Abstract  Fishing gear usage in small-scale coastal fisheries of Pelabuhanratu Bay, Indonesia was explained by two approaches: temporal fishing gear allocation analysis and adaptive responses of fishers to external factors, especially climate and abundance of target species. Gear usage, with the exception of hand lines and seine nets, was more inte...

To develop mitigation measures for reduction in incidental catch of seabirds in tuna longline fisheries, the hook sinking speed in ten types of branch lines used by Japanese tuna longline vessels was investigated. Also, to improve sinking speed of the hook, two new techniques were tested: material of 10 m line close to the hook was altered from pol...

The size selectivity of a trammel net for herded oval squid Sepioteuthis lessoniana in Tateyama Bay, Chiba Prefecture, was estimated by comparison between the mantle length frequency distributions of oval squid caught by a trammel net and by a set net. The measured mesh sizes of the inner net of the trammel net and of the final section of the set n...

In order to understand the capture characteristics of a trammel net for herded oval squid Sepioteuthis lessoniana, fishing method and catch composition were surveyed in Tateyama Bay, Chiba Prefecture, in 2002 and 2003. A trammel net with an inner mesh size of 85 mm and an outer mesh size of 360 mm was used in the fishing operation. The trammel net...

1 tality. However, improving the gear selectivity without reducing damage and stress incurred dur-ing capture and escape may not be the most appro-priate way of protecting immature fish. In most cases, mechanical selection through fishing gear modification has been carried out without research into the survival of fish after escape (Chopin et al. 1...

The change in visual acuity and retinal adaptation according to light intensity was investigated for red sea bream Pagrus major. Visual acuity was estimated by a behavioral training method as 0.24 in 500 lx, 0.19 in 100 lx, 0.15 in 10 lx and 0.10 in 1-0.1 lx. Retinal adaptation was examined by a histological method in fish exposed to the same light...

The heart rate change during swimming exercise and recovery for carp Cyprinus carpio was measured by electrocardiogram observation. Heart rate increased significantly during exercise at higher speeds of 2-5 BL/s. The maximum value was 2.7 times the control value, while the rate of increase was not proportional to the swimming speed. The heart rate...

The cross sectional pattern of the underwater illuminance for the coastal squid jigging boat was calculated with a formula based on the line light source model which consists of the spatial luminous distribution of fishing lamp and the surface reflectance of light by Fresnel's law. The calculated pattern of the contour map of the cross sectional un...

: For the purpose of promoting the academic cooperation in Asia, the Japan Society for the Promotion of Science (JSPS) offers the Core University Program in fisheries science. This program was initiated by Indonesia in 1995, and followed by Philippines in 1998, Thailand in 2000, and Korea in 2001. Each Core University designated in Japan and its co...

Swimming performance of white-spotted conger was examined by forcing the fish to swim at various given flow speeds in the small-size swimming channel. Maximum sustained speed was estimated at around 1.1 BL/s for fish of 23.5-33.0 cm TL at 18.3 degrees C. The beating frequency of tail tip increased linearly related to the increase of swimming speed....

In order to determine the accumulation performance of differing set-net designs, catch analysis was conducted upon small scale set-nets of both the single-trap and double-trap type. Total catch per haul was significantly higher after the design change to the double-trap net. The ratio of catch per intermittent haul to successive haul was defined as...

The development of visual acuity in yellowtail were investigated by histological examination of the retina for 43 individuals (BL 15-392 mm). The lens diameter increased from 0.5 mm to 7.1 mm proportionally with the growth of body length. The cone density was found to fit in an exponentially declining curve, where it steeply decreases in the range...

The survival of Japanese whiting Sillago japonica and by-catch species captured by a sweeping trammel net was examined to assess the effects of differing species, captured conditions, and body lengths on survival, in Tateyama Bay, Chiba Prefecture, Japan. All the live samples were kept in laboratory tanks for 4 days of successive survival observati...

To determine the mesh selectivity of a sweeping trammel net for Japanese whiting Sillago japonica, experimental fishing operations using three different inner net mesh lengths (27.5, 31.0 and 33.5 mm) were carried out in Tateyama Bay, Chiba Prefecture, Japan from August to November 1996 and from April to May 1997. The length mode of captured fish i...

Visual axis of red sea bream Pagrus major was analyzed from the laboratory experiment on the feeding behavior in the dome-shaped tank. Feeding time was measured for the food presented at random on the inside wall of the dome, for 33 different directions of equal distance from the starting gate. The fish was observed to approach the food directly to...

To investigate the stress response of Japanese whiting Sillago japonica associated with the capture process of sweeping trammel net, plasma cortisol levels of the fish were measured as a stress index. The result revealed that the plasma cortisol levels increased from just after capture to 24 hours, then tended to decrease in 72 hours by keeping the...

Developmental changes in the visual acuity of red sea bream were investigated by histological examination of the retina for 61 individuals from juvenile to adult stage (BL 23-609mm). The highest cone density could be located in the dorso-temporal area of the retina. The visual acuity depends both on the eye lens diameter and the cone density on the...

The relationship between the distribution of Japanese common squid beneath a boat and under water irradiance of fishing lights was investigated during nighttime jigging operations off the Oki Islands, Shimane Prefecture in November 1995. The downward spectral irradiance under fishing lights of a power of 300kW (metal-halide type; white) was continu...

The spectral distribution patterns of downward irradiance were studied in the squid jigging grounds of the Sea of Japan to examine fishing light transmittance according to the optical characteristics in areas and seasons. The optical water types in the summer season in the Sea of Japan can be classified into oceanic type IB-II for Shakotan peninsul...

Line source model of fishing lamps for under-surface illuminance around the Coastal squid jigging boat was calculated with a formula based on the line source model of fishing lamps, the spacial luminous distribution of HID lamp and the surface reflectance by Fresnel's law. Calculated patterns of illuminance around the boat showed a good fit to the...

The stimulating effect of strobe light on jack mackerel Trachurus japonicus was examined for the heart rate change under different flash frequencies. Heart rate change was clearly observed to increase during strobe flashing, with a tendency of sudden decrease immediately after ending of the stimulus. The observation was repeated three times for eac...

In order to identify the relationship between the hauling interval and the catch quality and quantity of the small scale set-net, experimental operations was conducted in the fishing grouns of Tateyama Bay, Chiba prefecture in August, 1995. The experimental protocol of the bag net hauling procedure was designed to vary in different hauling interval...

The stimulating effect of strobe light on jack mackerel Trachurus japonicus was examined for the heart rate change under different flash frequencies. Heart rate change was clearly observed to increase during strobe flashing, with a tendency of sudden decrease immediately after ending of the stimulus. The observation was repeated three times for eac...

Fisheries management policy to increase escapement of non-target species and sizes of fish from fishing gears is generally based on the assumption that injury and stress received during the capture-escape process do not result in a significant level of mortality after escape. However, there has been little research to validate this assumption. To i...

The discarding of non-target species and sizes of fish by commercial fishing vessels is a common practice in many fisheries around the world. Efforts to reduce discarding in North Sea fisheries were initiated over 100 years ago, and were the precursor to development of mesh-selectivity research for many European countries. In most cases mechanical...

The spectral distribution of downward irradiance in the sea around a squid jigging boat (<30Gt) was investigated with special reference to the type and total kW output of fishing lamps, in the fishing ground of Toyama Bay and off Tsushima Island in June and November 1994, respectively. The downward irradiance distributions in the waters shallower t...

In order to understand the capture process of trolling gear, the fish response towards a trolling line was observed by a towed underwater video camera. Fishing tackle consisted of a main line, a depressor board, a leader line, and a lure. The underwater video camera was mounted on the depressor board to observe and record the sequence of responses...

The capture of immature fish in many commercial fisheries is controlled by restricting the use of fishing gears or elements of fishing gears that prevent the escape of immature fish. Improving the selective characteristics of fishing gear is based on the assumption that fish escaping are not seriously damaged and able to make a complete recovery. I...

In order to identify the entrapping time of fish into the set-net, experimental operations were conducted at a small scale set-net fishing area in Tateyama Bay, Chiba prefecture. The bag net was hauled up 6 times per day at 03:00, 07:00, 11:00, 15:00, 19:00 and 23:00 hours at 4 hour intervals. A total of 60 hauls at 6 different times of day were ma...

The swimming endurance was measured in a flume tank at 20°C water temperature for 14.5--21 cm long jack mackerel Trachurus japonicus. The endurance time (E. s) decreased drastically as the speed (U. BL/s) increased. An equation log E= -0.35 U+5.63 was derived. The maximum sustained speed of 6.2 BL/s was recorded for a 14.5 cm fish. Swimming at 10.8...

The migrating behaviour of fish schools such as jack mackerel Trachurus japonicus, spotted mackerel Scomber australasicus, and Japanese anchovy Engraulis japonicus was investigated in set-net fishing grounds by means of sonar image records. The spotted mackerel and Japanese anchovy schools moved at an average speed of 18-19cm/s, while the jack mack...

The retinal adaptations were examined for the walleye pollock Theragra chalcogramma taken at different times of day and night from different depths of trawling in the north Pacific. Even in the daytime, some retina sampled from depths of 150 to 200m showed a tendency towards dark adaptation. This suggests the inactive response of the walleye polloc...

In order to examine the functions of the red and white muscle of jack mackerel Trachurus japonicus during swimming locomotion, the fish was dissected to observe muscle distribution along the body. The electrical activity of the lateral muscle was analyzed using an electrophysiological technique. The ratio of red muscle to total muscle in a transver...

Fish behaviour surveys in the Nayaura set-net fishing ground off Mie prefecture were carried out in relation to the fish leading effect of the natural bank.The topography of the fishing ground was surveyed by a side-scan-sonar and characterized by a long bank surrounded by large and small rocky reefs, which extend parallel to the leadernet from the...

The herding effect of an air bubble curtain was examined for jack mackerel Trachurus japonicus in a 2m wide annular trough set in an outdoor tank of 7m diameter. Sixteen air pipes were radially arranged on the bottom at the same interval. The bubbling position can be alternated in order by the valve switches which are connected to the air blower. G...

In order to develop a new method for the control of fish behaviour, the authors observed the response of fishes to an air bubble curtain by laboratory experiments. An annular trough set up in a small scale test tank was intercepted by the air bubble curtain, which was rotated along the trough. The response toward the air bubble curtain of Japanese...

The muscle twitch contraction time of Walleye pollock Theragra chalcogramma was measured in relation to fish size and muscle temperature, on board a Northern trawler in the Okhotsk Sea. The contraction time was defined as the time period from the electric pulse of 2ms wide and 5-20V, to the peak of muscle twitch contraction. The scale effect was ob...

Sustained swimming of bluefin tuna was analysed from video recordings made of a captive patrolling fish school [lengths (L) 1.7–3.3 m, body mass (M) 54–433 kg]. Speeds ranged from 0.6 to 1.2 L s−1 (86–260 km day−1) while stride length during steady speed swimming varied between 0.54 and 0.93 L. Maximum swimming speed was estimated by measuring twit...

An experiment was conducted to measure the tail beat frequency of jack mackerel Trachurus japonicus of 5.88 to 15.60 cm in fork length, at the different swimming speeds in a small water channel observed with VTR system. The tail beat frequency increased in proportion with the swimming speeds from 5.5 to 54.0 cm/s. The equations for estimating the s...

Behavioural studies of fish towards the slope are conducted in relation to a set-net. Ten individuals of crucian carp Carassrus auratus are tested in an experimentai tank which consists of a flat and a sloped area in Experiment I and the sides of a trap box attached to the slope in Ex-perimentII. In equal conditions of illumination in Exp. I, the d...

Effects of immersion time in coastal set-lines have been studied through six pairs of simultaneous operations conducted on the same ground of Sagami Bay. Using ordinary fishing methods the first operations were conducted around sunrise, and the second ones were set after sunrise and hauled in the afternoon, overlapping the two sets so as to elongat...

An experimental fishing was conducted at Sagami Bay in 1977, to study the catching mechanism of a bottom long-line. Twelve experiments were made, each having a different immersion time of the gear, and the relationships between the catch and immersion time were determined. During the short period of time that followed the setting of the long-line,...

ABSTRAK Secara umum ada dua jenis lampu yang digunakan untuk mengumpulkan ikan yang ditangkap oleh bagan, yaitu lampu petromaks dan lampu listrik. Lampu petromaks banyak digunakan pada bagan ukuran kecil (seperti bagan rakit di Pelabuhan Ratu), sedangkan lampu listrik digunakan pada bagan dengan ukuran yang lebih besar (di Selat Makassar dan Teluk...