Dear MARMAM subscribers, Increasingly various ocean enterprises are introducing high frequency communication signals into marine habitats in the 20kHz to 100kHz range. These signals are used for many tasks including navigation beacons, locating/orienting signals, current profilers, tidal altimeters, and multi-nodal communication networks for autonomous equipment monitoring and control. These frequencies overlap odontocete bio-sonar frequencies and depending on the task and required broadcast reach, signals from some of this equipment exceeds regulatory noise exposure thresholds for marine mammals. Unfortunately much of the long-term acoustical monitoring of marine environments is performed at a sample rates well below the broadcast frequencies of concern and thus these signals are going unnoticed. But we do have some spectrograms that have been sampled at a higher rate - 92kHz and above where continuous high frequency signals are quite apparent - and persistent. We have some good ideas about where these technologies can be found, and a rough idea on how fast these technologies are proliferating globally. But due to the cost associated with marine reconnaissance we don't have a lot of empirical data. We are seeking recordings or spectrograms that would help us characterize/quantify the development and proliferation of signals that overlap this bioacoustic niche. Thanks in advance for your assistance. Michael Stocker http://www.planetwhale.com/img/618ocr_logo_041510_v51297800494.jpg Michael Stocker, Director Ocean Conservation Research P.O. Box 559 Lagunitas, CA 94938 Mobile: 415-488-0553 Email: <mailto:mstocker@ocr.org> mstocker@ocr.org <http://www.ocr.org/> http://www.ocr.org
