THE ULTRASONIC TRACKING OF MEKONG GIANT CATFISH PANGASLANODON GIGAS IN MEKONG RIVER

Southeast Asia Sea Turtle Associative ResearchBangkok, Thailand, 16-19 December 2002The Mekong giant catfish Pangasianodon gigas is endemic to the Mekong River, measuring up to 3 m in length and weighing in excess of 300 kg. The number of the wild catfish in the Mekong River has decreased due to the development of the Mekong River these days. Therefore, ecological researches are urgently needed to conserve the catfish. However, there was no method to monitor the movement of the catfish continuously in the Mekong River. The objective of this study was to test a feasibility of coded ultrasonic tracking system to monitor the contineous movement of the catfish in such a large river, the Mekong River. We released ten cultured catfish in the Mekong River. The catfish tended to move downstream or stayed around the release point just after the release. Four of ten catfish moved upstream for 60 km in 2-3 days although one fish moved downstream for 40 km. This tracking system that we tested could be a feasible system to monitor the continuous movement of the catfish in such a large river, the Mekong River

Growth rates, relative growth and a potential aging method using vertebral centra in Silurus biwaensis(Siluriformes: Siluridae)

Relative growth and relationship between age and growth in Silurus biwaensis were examined on the basis of the body size data of the catfish collected from Lake Biwa and the reared catfish which were hatched from artificially inseminated eggs. Although it had been reported that the proportion of head length to body length increased with growth in S. biwaensis, such a relationship was not found for 218 catfish that were examined in this study. On the other hand, the proportion of head length to head width significantly decreased with SL in females. This result indicated that the narrow head shape peculiar to S. biwaensis becomes slightly squarer in bigger females. The three catfish reared from the hatching grew to 196-410mm SL for 2.7 years (73-152mm/yr). This growth rate was in contrast with that of a tagged adult male, which grew only 50mm from 460mm SL to 510mm SL in the lake for two years (25mm/yr). These results suggested that the growth of the adults might extremely slow down after the fast growth at the immature stage. This study also reported that the number of transparent zones in vertebral centra of S. biwaensis increased with growth. The vertebral centrum may possibly be utilized as an age indicator for this species and the other kinds of Silurid

Characteristics of patients hospitalised in an emergency department observation unit in Japan

In Japan, transporting elderly patients to emergency departments has recently posed serious problems, including a longer average time from patients’ initial emergency calls to their arrival at hospitals. To manage emergency departments more efficiently, many hospitals in the United States and some other developed countries, including Japan, introduced emergency department observation units (EDOU). However, because the usefulness of EDOUs in managing elderly patients remains uncertain, we analysed data of patients admitted to a Japanese university hospital’s EDOU to gauge its efficacy. We followed 1,426 patients admitted to the hospital’s EDOU from 1 January 2011 to 31 December 2014. The average age of patients who stayed in the EDOU increased, whereas the average length of time that they spent there decreased. Although the percentage of patients older than 65 years increased slightly, from 36.42% (2011–2012) to 37.73% (2013–2014), the proportion of those patients between the two periods did not significantly change (P = .61). Moreover, their average length of stay was 2.16 ± 0.91 days, whereas patients younger than 65 years stayed for significantly less time (1.92 ± 0.82 days). By condition, approximately 36% of patients older than 65 years presented with non-neurosurgical trauma, approximately 59% presented with other forms of trauma, but proportions of both categories of trauma were significantly smaller in patients younger than 65 years (nonneurosurgical trauma, 23%; all trauma, 47%). Most elderly patients with limb trauma prepped for surgery were transferred to other hospitals after a few days. Results suggest that the EDOU at the university hospital has served to as a buffer for regional emergency medical systems in Japan, especially given the continued ageing of the Japanese population

Biotelemetry study on marine lives using codec ultrasonic transmitter

Southeast Asia Sea Turtle Cooperative Research (SEASTAR2000)ORGANISED BY KYOTO UNIVERSITY, JAPAN ; THE UNEVERSITY OF TOKYO, JAPAN ; PHUKET MARINE BIOLOGICAL CENTER, THAILAND ; SEA TURTLE CONSERVATION STATION, THAILAND ; MARINE FISHERIES DIVISION, DEPARTMENT OF FISHERIES, THAILANDPHUKET, Thailand 11-13, December 2001lnformatics Research Center for Development of Knowledge Society IntrastructureWe employed coded ultrasonic transmitters (V8SC-6L, Vemco Ltd., Canada) in order to track many fishes simultaneously. We were able to track up to 256 different fishes using the transmitters on the same frequency. In this study, we used one VR28 tracking system (Vemco Ltd., Canada) and two VR1 tracking systems (Vemco Ltd., Canada) together to track black rockfishes that inhabited the seawall of the Kansai International Airport. Many tagged black rockfishes were identified at the same place respectively for a long time using the transmitters. These results show that the combination of the VR28 receiver system and the VR1 receiver system is a powerful tool to provide us the useful data including position of the tagged fish and the time of fish attendance in certain areas

Growth rates, relative growth and a potential aging method using vertebral centra in Silurus biwaensis(Siluriformes: Siluridae)

Relative growth and relationship between age and growth in Silurus biwaensis were examined on the basis of the body size data of the catfish collected from Lake Biwa and the reared catfish which were hatched from artificially inseminated eggs. Although it had been reported that the proportion of head length to body length increased with growth in S. biwaensis, such a relationship was not found for 218 catfish that were examined in this study. On the other hand, the proportion of head length to head width significantly decreased with SL in females. This result indicated that the narrow head shape peculiar to S. biwaensis becomes slightly squarer in bigger females. The three catfish reared from the hatching grew to 196-410mm SL for 2.7 years (73-152mm/yr). This growth rate was in contrast with that of a tagged adult male, which grew only 50mm from 460mm SL to 510mm SL in the lake for two years (25mm/yr). These results suggested that the growth of the adults might extremely slow down after the fast growth at the immature stage. This study also reported that the number of transparent zones in vertebral centra of S. biwaensis increased with growth. The vertebral centrum may possibly be utilized as an age indicator for this species and the other kinds of Silurid

Comparison of cerebral activation between motor execution and motor imagery of self-feeding activity

Motor imagery is defined as an act wherein an individual contemplates a mental action of motor execution without apparent action. Mental practice executed by repetitive motor imagery can improve motor performance without simultaneous sensory input or overt output. We aimed to investigate cerebral hemodynamics during motor imagery and motor execution of a self-feeding activity using chopsticks. This study included 21 healthy right-handed volunteers. The self-feeding activity task comprised either motor imagery or motor execution of eating sliced cucumber pickles with chopsticks to examine eight regions of interest: pre-supplementary motor area, supplementary motor area, bilateral prefrontal cortex, premotor area, and sensorimotor cortex. The mean oxyhemoglobin levels were detected using near-infrared spectroscopy to reflect cerebral activation. The mean oxyhemoglobin levels during motor execution were significantly higher in the left sensorimotor cortex than in the supplementary motor area and the left premotor area. Moreover, significantly higher oxyhemoglobin levels were detected in the supplementary motor area and the left premotor area during motor imagery, compared to motor execution. Supplementary motor area and premotor area had important roles in the motor imagery of self-feeding activity. Moreover, the activation levels of the supplementary motor area and the premotor area during motor execution and motor imagery are likely affected by intentional cognitive processes. Levels of cerebral activation differed in some areas during motor execution and motor imagery of a self-feeding activity. This study was approved by the Ethical Review Committee of Nagasaki University (approval No. 18110801) on December 10, 2018

Evidence of homing of black rockfish Sebastes inermis using biotelemetry

The black rockfish Sebastes inermis is one of the most important fishery species along the coast from southern Hokkaido to Kyushu, Japan and is often found in rocks and Zostera areas. We conducted biotelemetry using coded ultrasonic transmitters to clarify the movement of the black rockfish that inhabited the seawall of the Kansai International Airport. We released 25 black rockfish at two points. One was the airport seawall and the other was side shallows off the Sensyu district. Seventeen black rockfish returned to their capture site after release. We used the V-test to determine whether the direction of movement was random or orientated. The black rockfish moved at random along the seawall within some hours after release (P> 0.05). Four hours after release, they moved to their home site intentionally (P< 0.0025)

Role of olfaction and vision in homing behaviour of black rockfish Sebastes inermis

How fish find their original habitat and natal home remains an unsolved riddle of animal behaviour. Despite extensive efforts to study the homing behaviour of diadromous fish, relatively little attention has been paid to that of non-diadromous marine fish. Among these, most rockfish of the genus Sebastes exhibit homing ability and/or a strong fidelity to their habitats. However, how these rockfish detect the homeward direction has not been clarified. The goal of the present research was to investigate the sensory mechanisms involved in the homing behaviour of the black rockfish Sebastes inermis, using acoustic telemetry. Vision-blocked or olfactory-ablated rockfish were released in natural waters and their homing behaviours compared with those of intact or control individuals. Blind rockfish showed homing from both inside and outside their habitat. The time taken by blind fish to reach their home habitat was not significantly different from that of the control fish. In contrast, most olfactory-ablated fish did not successfully reach their original habitat. Our results indicate that black rockfish predominantly use the olfactory sense in their homing behaviour