Agency Stops Seismic Tests; Worries About Dolphins With sick and dead dolphins turning up along Louisiana's coast, federal regulators are curbing an oil and natural gas exploration company from doing seismic tests known to disturb marine mammals. The U.S. Bureau of Ocean Energy Management has told Global Geophysical Services Inc. to not conduct deep-penetration seismic surveys off the Louisiana coast until May when the bottlenose dolphin calving season ends. The agency says the surveys are done with air-guns that can disrupt mother and calf bonding. The company says it laid off about 30 workers because of the restriction, which it called unnecessary. Environmental groups are suing BOEM over the use of underwater seismic equipment and say the restrictions should be extended to surveyors across the Gulf of Mexico.