| Autor: |
Joseph E. Blue, Edmund R. Gerstein, Steven E. Forsythe |
| Rok vydání: |
2002 |
| Předmět: |
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| Zdroj: |
The Journal of the Acoustical Society of America. 112:2430-2430 |
| ISSN: |
0001-4966 |
| DOI: |
10.1121/1.4779972 |
| Popis: |
Ship collisions with whales and other marine animals occur near the surface. Here Snells law applies and can play a crucial role in the survival and behavioral ecology of marine mammals. In this study we investigated some theoretical constructs of near surface sound propagation that can render whales vulnerable to collisions. Empirical measurements support predictions and demonstrate that propeller noise directly ahead of many large vessels can become indistinguishable from the ambient noise. Large acoustic shadows in front of approaching ships and the confluence of near surface acoustic propagation effects seriously challenge the whales’ ability to detect and locate approaching ships. At the surface, ship noise profiles are loudest at the stern and off the port and starboard sides while remaining remarkably quiet at the bow. Whales with calves swimming near the surface alerted to ship sounds may seek refuge by actively swimming into the quieter shadow zones directly ahead of vessels. Once here, hydrodynamic forces could overcome calves and adults. While this behavioral scenario has not been investigated, acoustic measurements reveal a disturbing paradox, suggesting the circumstance is plausible. Further investigations may result in directional acoustic solutions that light‐up these acoustic shadows and can alert whales in time to avoid injury. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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