The Navy, as planned, has released its final EIS governing mid-frequency active sonar training along the entire eastern seaboard, as well as a similar EIS for southern California sonar use.  While the documents consider formal Alternatives that would limit sonar training to specific areas—either permanently or seasonally, based on marine mammal breeding, feeding, and migration patterns—the Navy concludes that these restrictions would not make a significant difference in how many whales are affected, so they propose to continue training at will within their entire current Operation Areas (OPAREAS).  The Navy stresses the need to have the widest possible flexibility to train in areas of various depths, seafloor profiles, etc., and apparently feel that any areas set off limits would be sorely missed at some point.  It is somewhat surprising that the Alternatives that include restrictions designed to avoid areas with high densities of marine mammals do not lead to significantly fewer exposures to sonar signals; this leads to questions about how the exclusion areas were chosen, though the more likely explanation is that animal densities are relatively low everywhere, and the physical impacts being assessed by the Navy occur only at very close range (500m for temporary hearing loss, 10m for permanent hearing loss), while the behavioral effects are spread over very large areas (easily 50km and up to 130km from the ship).  The Navy’s proposed mitigation measures include the standard procedures they have been using for several years, including shut-downs when whales are within 200 yards and reducing sonar power when whales are within 1000 yards.  Given that similar safety measures have been challenged in the past (for specific training missions in Hawaii and California), with additional mitigation, including coastal zone restrictions and some other exclusions zones, being imposed, it seems likely that these proposals will face legal scrutiny.  In the recent Supreme Court case, the Navy did not appeal some territorial restrictions, but did appeal increased shut-down zones; this may indicate that they would negotiate a settlement that included some concession to those wanting more “off limits” areas.  However, it’s also quite possible that the Navy would resist a coastal exclusion, since one of their top concerns in sonar surveillance is near-shore (littoral) combat.  It is important to bear in mind that these EIS’s, and all the legal challenges to mid-frequency active sonar to date, address only sonar training missions; the Navy is free to do as it wishes during normal operations at sea, and indeed, hundreds of US ships use the system routinely around the world.   (Conversely, the Navy did negotiate restrictions in operational deployment of their more powerful Low-Frequency Active Sonar, which is only being used in specific parts the Pacific basin, rather than worldwide.)

Here is the Acoustic Ecology News Digest item for this report, with links to further information:

Navy Releases Final EISs for Sonar Training in Southern California, Entire East Coast – As planned, the Navy has released its final Environmental Impact Statements covering sonar training in coastal ranges and Operating Areas along the eastern seaboard and southern California. The documents consider alternatives including selecting specific areas for sonar training, both permanent and seasonally-shifting, to avoid concentrations of marine life, or designating specific areas of concern to always avoid. However, the “operationally” Preferred Alternative is to continue with the status quo of using sonar anywhere within the operational areas that the Navy deems useful for training purposes.

AFAST Operation Areas: Current status quo sonar training zones
Image from AFAST EIS Executive Summary

In the case of the Atlantic Fleet Active Sonar Training (AFAST) document, the analysis of how many marine mammals would be affected by sonar suggests that there is generally not a dramatic difference between the alternatives, in terms of how many animals would be close enough to suffer temporary hearing loss (the Navy predicts no mortalities under any scenario). A more significant, but still not especially dramatic, decrease in behavioral disruption is predicted under the alternatives that train in specific areas. Sources: The Virginian-Pilot, 10/12/08 [READ ARTICLE] AFAST EIS [DOWNLOAD PAGE] [READ EXECUTIVE SUMMARY]