A new report issued in the wake of an active sonar mitigation workshop held by the European Cetacean Society calls unequivocally for sonar training to be limited to relatively small dedicated areas. By contrast, the US Navy continues to insist that it needs access to nearly the entire eastern seaboard and most of the west coast as well, in order to have enough flexibility to train “realisically.” The ECS working group report, by an impressively diverse set of researchers ranging from NRDC’s Michael Jasny to Woods Hole scientist Peter Tyack, calls on the world’s navies to “commit without delay” to “minimum procedures” including:
- “Identify a limited number of locations to which (sonar) exercises can be confined,” and to “avoid important oceanographic features, such as canyons, steep walls, and seamounts, persistent upwellings, and bays…until such time as reliable extensive surveys and models are available for a given region”
- Use Passive Acoustic Monitoring, with observation times extended to increase the likelihood of beaked whales being found if present (2 hours minimum)
- Identify and avoid key biological hot spots; these avoidance restrictions should apply to all exercises, not just large-scale ones
- Limit activity to daylight hours whenever possible; require good visibility for some types of sonar use (e.g. brief tracking exercises and sonar research, development and evaluation) even if they are not easily applicable to others (e.g. multi-day free play exercises).
- “For beaked whales (and likely for other species and situations), a conservatively defined radius would extend to the isopleth where the risk of significant behavioural effects becomes more than negligible (acknowledging that this might be beyond the radius of visibility in some cases)”
This final point is nearly as game-changing as the first one. Setting the threshold for safety radii to assure that behavioral effects are “negligible” would create a much more precautionary standard than the current threshold of avoiding “significant” impacts. Likewise, acknowledgment that safety radii may need to be larger than can be visually observed is a proper reflection of current understanding of behavioral impacts, which commonly occur at relatively moderate sound levels for many species.
The “Technical Report on Effective Mitigation for Active Sonar and Beaked Whales” represents the shared expertise of 14 scientists, including some working for conservation groups (NRDC’s Michael Jasny and WDCS’s Sarah Dolman), several who have been relatively outspoken with their concerns about noise (Andrew Wright, Michel Andre), and notably, two fairly cautiously mainstream long-time acoustics researchers (UK’s Peter Evans and WHOI’s Peter Tyack).
Dolman, S.J., Aguilar de Soto, N., Notabartolo di Sciara, G., Andre, M., Evans, P.G.H., Frisch, H., Gannier, A., Gordon, J.C., Jasny, M., Johnson, M.A., Papanicolopulu, I., Panigada, S., Tyack, P.L. and Wright, A.J. 2009. Technical report on effective mitigation for active sonar and beaked whales. Report from the European Cetacean Society Conference Workshop: Beaked whales and active sonar: transiting from research to mitigation. Istanbul, Turkey. DOWNLOAD ECS REPORT HERE
SEE EUROPEAN CETACEAN SOCIETY RESOLUTION ON SONAR MITIGATION