Analysis of diving behavior of Adelie penguins using acceleration data logger

Acceleration data loggers were attached to five adult Adelie penguins at Hukuro Cove, Lutzow-Holm Bay in austral summer 1997/1998. The loggers recorded time series data of speed, depth, surging acceleration and swaying acceleration in flush memories inside. From time series analyses, the frequency of 2- to 3-Hz was found in the surging acceleration during descent in a straight line. The cycle seemed to correspond to wingbeat frequency of the Adelie penguin. The relation between wingbeat frequency and diving depth was that the frequency ranged from 1.5-Hz to 3.0-Hz when the penguins dive in water shallower than 30-m and was over 2.5-Hz in water deeper than 50-m. The acceleration data logger is a powerful tool to estimate kinematic parameters of free-range marine animals

Local knowledge of the Mekong giant catfish at the Sirikit Dam Reservoir, Northern Thailand

December 13-14, 2006, Siam City Hotel, Bangkok, ThailandSome 103, 276 hatchery-reared Mekong giant catfish have been released into the Sirikid dam reservoir from 1984 to 2006. Local knowledge of the catfish was assessed from two fishermen at the reservoir in December 2006 and March 2007. Both fishermen used a gill net to capture the Mekong giant catfish. The experience of one fisherman suggests that the catfish might move around the old channel in the reservoir. The Mekong giant catfish captured in this reservoir by the other fisherman varied from 40 to more than 100 kg in weight. This suggests that the Mekong giant catfish might have grown greatly in the Sirikit dam reservoir and have been a fishery resource around the Sirikid dam reservoir basin

Preliminary result of the relationship between the breathing frequency and dynamic body acceleration

March 5-6, 2009, Bangkok, ThailandIn this study, the relationship between the breathing frequency and the dynamic body acceleration (DBA) of one hatchery-reared loggerhead turtle Carretta carretta was examined using acceleration data loggers. Two acceleration data loggers (M190L-D2GT, W1000-3MPD3GT, Little Leonard, Japan) were attached on the lower-beak and carapace of a hatchery-reared loggerhead turtle, respectively. Breathing was successfully detected from the angle and depth of the beak-attached data logger and DBA, which has been used as an index of activity levels (Wilson et al., 2006), was calculated from the forward acceleration of the carapace-attached logger. There was a positive correlation between the DBA in the previous dive and the breathing frequency; the relationship was exponential. The result suggests that the number of breaths increased exponentially after a more active dive

Deep neural networks based automated extraction of dugong feeding trails from UAV images in the intertidal seagrass beds

Dugongs (Dugong dugon) are seagrass specialists distributed in shallow coastal waters in tropical and subtropical seas. The area and distribution of the dugongs’ feeding trails, which are unvegetated winding tracks left after feeding, have been used as an indicator of their feeding ground utilization. However, current ground-based measurements of these trails require a large amount of time and effort. Here, we developed effective methods to observe the dugongs’ feeding trails using unmanned aerial vehicle (UAV) images (1) by extracting the dugong feeding trails using deep neural networks. Furthermore, we demonstrated two applications as follows; (2) extraction of the daily new feeding trails with deep neural networks and (3) estimation the direction of the feeding trails. We obtained aerial photographs from the intertidal seagrass bed at Talibong Island, Trang Province, Thailand. The F1 scores, which are a measure of binary classification model’s accuracy taking false positives and false negatives into account, for the method (1) were 89.5% and 87.7% for the images with ground sampling resolutions of 1 cm/pixel and 0.5 cm/pixel, respectively, while the F1 score for the method (2) was 61.9%. The F1 score for the method (1) was high enough to perform scientific studies on the dugong. However, the method (2) should be improved, and there remains a need for manual correction. The mean area of the extracted daily new feeding trails from September 12–27, 2019, was 187.8 m2 per day (n = 9). Total 63.9% of the feeding trails was estimated to have direction within a range of 112.5° and 157.5°. These proposed new methods will reduce the time and efforts required for future feeding trail observations and contribute to future assessments of the dugongs’ seagrass habitat use

Hatchery-reared F2 Mekong giant catfish spent their time above hypoxic water in the Mae Peum reservoir, Thailand

March 5-6, 2009, Bangkok, ThailandJuvenile and young hatchery-reared Mekong giant catfish Pangasianodon gigas have been released into reservoirs throughout Thailand. For the sustainable reservoir fishery of the giant catfish, new science-based fishery management measures are expected in Thailand, such as the establishment of protected areas. Therefore, the habitat use and movement patterns of the hatchery-reared giant catfish have been investigated in the Mae Peum reservoir from 2003 to 2005. Our results suggest that the hatchery-reared fish spent their time in shallow depths above hypoxic water in the reservoir. The fish which have been reared in a fish pond may recognize and avoid hypoxic conditions

Study on behavioral characteristics of wild and hatchery-reared red tilefish

Organized by Graduate School of Informatics, Kyoto University ; JSPS Bangkok Liaison Office ; Japanese Society of Bio-logging Science ; Informatics Research Center for Development of Knowledge Society InfrastructureDecember 13-15, 2004, Imperial Tara Hotel, Bangkok, ThailandThe diel activity of red tilefish Branchiostegus japonicus was studied using two different methods : analysis of biotelemetry records and video observation. We have acquired the biotelemetry tracking records of the red tilefish which were released in Maizuru Bay and tracked from January 2003 to February 2004. The records ware compared to the time of sunrise and sunset, the duration of sunshine, and the lunar cycle, which may influence on light conditions. Whilst the fish showed diel activity, the fish changed their behaviors along with the time of sunrise and sunset; the fish probably moved out of their burrows in the daytime and retreated into the burrows at night. We could not find a clear relationship between the behavior and the other two factors. In the laboratory, the behavior of one hatchery-reared individual was recorded by video for five days in the experimental tank where the light condition changed periodically over 24 hours. The fish was more active in the light periods (550 lx) compared to in the dark periods (0 lx). Since the results from the two methods probably compliment one another, further experiments using the two methods will reveal the detailed behavior of red tilefish

Development of detection device for dugong calls

December 15-17, 2007, Royal Phuket City Hotel, Phuket, ThailandAn acoustical approach for research on marine mammals has been a very active research method in recent years. Dugong (Dugong dugon) is one of the highly endangered species, which are strictly-marine herbivorous and mainly inhabit coastal areas. In order to detect dugong calls from recorded data, several algorithms have been adapted by researchers in the analyzing process. However, the number of misses in the detection is still non-zero. The sound of snapping shrimp recorded in a wide range (2-300 kHz) is one of the main background noises that makes the detection of dugong calls difficult in warm shallow waters. Impulse elimination was employed in the system to get rid of the snapping shrimp noise. In order to improve the performance of the detection system by increasing the detection rate and decreasing the number of misses, two new algorithms were tested in the experiment. The experimental results for the new algorithms including impulse elimination and the cepstrum method are presented in this paper

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