P.V. Haner A.G. Maule J.W. Beeman 1998 <p><span>A miniature pressure-sensitive radio transmitter (tag) was evaluated and field tested as a tool for determining the depths of juvenile salmonids. The tag had an effective radiated power of −19.7 decibels (1 mW reference), dimensions of 23 mm × 7 mm, and a weight of 2.2 g in air. The pulse rate of the tag increased with pressure, resulting in an expected tag life of approximately 11 d at the water surface and 7.5 d at 10.5 m. The tags were accurate to within 16 mm with 95% of observations within ±0.32 m of the true depth. The resolution of the tags was 0.2 m. Errors in indicated depth resulting from differences between the calibration and operating temperatures were minimized by means of a correction factor. Tags surgically implanted in juvenile steelhead </span><i>Oncorhynchus mykiss</i><span> indicated a depth 0.2 m less than the same tags in water. This difference was not affected by pressure or temperature and was rectified by adjusting data from tags in fish. A test tag in a Columbia River reservoir was detected from distances of 1,133 m at a depth of 2 m and 148 m at a depth of 14 m. Results ind</span></p> application/pdf 10.1577/1548-8675(1998)018<0458:EOANMP>2.0.CO;2 en American Fisheries Society Evaluation of a new miniature pressure-sensitive radio transmitter article