Sir

Your News story “Push to protect whales leaves seafloor research high and dry” (Nature 428, 681; 200410.1038/428681a) reports that the Lamont-Doherty Earth Observatory survey of the 65-million-year-old Chicxulub meteorite crater, coordinated by the US National Science Foundation (NSF), was cancelled because of concerns that the airguns used could harm marine mammals.

As a science adviser for Seaflow — a conservationist organization with a mission to reduce harmful underwater noise (see http://www.seaflow.org) — I am concerned that the only instrument we have to protect the ocean environment resides in legislation protecting marine mammals.

Lamont-Doherty did apply for marine mammal ‘incidental harassment authorization’, and received authorization from the National Marine Fisheries Service to deploy the airguns under the rules of the US Marine Mammal Protection Act. The Chicxulub survey was ultimately blocked by a Mexican environmental agency that was worried about marine mammals, but I believe that there are other good reasons to refrain from seismic airgun research until we know what effects the blasts have on the marine environment.

What is not included in US law, or even in the discussion, is the impact that airgun explosions have on fish populations.

There is evidence that seismic airguns can damage fish ears (R. D. McCauley et al. J. Acoust. Soc. Am. 113, 638–642; 2003). We also know that fisheries are compromised by airgun operations. The Chicxulub survey was to take place in 3,000 km2 of tropical waters at depths of 50–100 m. To ignore the probable impact that this study would have had on fish populations reveals an added dimension to the short-sightedness of the programme.

Although halting the survey may have been costly in the short term, it may make more sense to spend NSF money looking at the impacts of anthropogenic noise on fish. Once the biological research is more complete, geologists can do their research using methods that will not compromise the biota, raise the ire of fishermen and conservationists, or force action by environmental protection agencies.