Marine mammals remain at risk to sonar

THE ISSUE The federal government is poised to approve rules for the Navy's continued use of low-frequency sonar.

THOUGH not much is known about how sonar affects marine mammals, there are strong indications the sounds do harm whales and other species. Until more research can be done, the Navy has an obligation to limit the effects of its sonar devices and to develop methods and technology to prevent damage to ocean creatures.

The National Oceanic and Atmospheric Administration has given preliminary approval of rules that allow the Navy to use low-frequency active sonar under certain conditions for the next five years, saying monitoring shows it is unlikely marine mammals will be injured.

The NOAA says there has been "no documented evidence" that this type of sonar has damaged marine mammals. The equivocal conclusion reflects the impossibility of knowing for sure because the low-frequency sonar sends sounds over long distances and "evidence" is difficult to substantiate in the wide expanses and depths of the oceans.

The NOAA is correct to require the Navy continue to use protective measures when marine mammals are in areas where the sonar is employed and to shut down operations when they are within a mile of the sound source. The Navy should also collect data to help researchers understand sonar effects so that systems can be designed to mitigate harm.

Low-frequency active sonar is operational on only two ships the Navy uses in the Pacific and is not allowed to be turned on near the Hawaiian Islands. While that is of some comfort, marine animals note no human-set boundaries in their habitats and until more research is conducted they will remain at risk.