Study on marine animal behavior by micro-data tag

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To investigate behavior of marine animals, we developed the micro-data loggers which is deployed on the back of the animals to measure dive depth, ambient temperature, salinity, swim velocity, acceleration movement, heart rate and light level.We conducted the field experiment on harbor porpoises, auklets, cormorants, king penguins, loggerhead turtles and chum salmons. Those data loggers used in these studies were 14mm and 19mm in diameter and, 75mm in length. Two or three sensors were equipped on a single data logger to measure several parameters simultaneously in the same time scale.Although detailed processing and analysis of data is still under going, we could obtained several unique findings from preliminary analysis as followings.1. Harbor porpoises dived continuously without taking any extended surface time. While their continuous diving, they had two type of dive profiles, shallow and deep. They also maintained low metabolic rate during diving (18ml O_2/m).2. Auklet, 500g body mass, dived for 2-3 minutes and reached 50m depth. This dive duration was far exceeded it's calculated aerobic dive limit. From the results we hypothesized that auklet, smaller diving birds developed physiological dive adaptation to diminish effect of increased lactic acids.3. Chum salmons showed frequent vertical movement ranging 0-150m, and sometimes avoid the warm temperature waters by swimming deeper waters. It also showed that fresh water zone was no longer barrier when they went up to the river from sea water.