Typical restrictions in MPAs include ones on fishing, oil and gas mining and tourism. Other restrictions may limit the use of ultrasonic devices like SONAR (which may confuse the guidance system of cetaceans), development, construction and the like. Some fishing restrictions include what are called "no-take" zones, which means that no fishing is allowed. Less than 1% of MPAs are no-take in the United States. Ship transit can also be regulated or banned, either as a preventive measure or to avoid direct disturbance to certain species. The degree to which environmental regulations affect shipping varies according to whether MPAs are located in territorial waters, exclusive economic zones, or the high seas. The law of the sea regulates these limits.