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 "no-take" zones, which means that no fishing is allowed. Less than 1% of US MPAs are no-take. Ship transit can also be restricted or banned, either as a preventive measure or to avoid direct disturbance to individual 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. Most MPAs have been located in territorial waters, where the appropriate government can enforce them. However, MPAs have been established in exclusive economic zones and in international waters. For example, Italy, France and Monaco in 1999 jointly established a cetacean sanctuary in the Ligurian Sea named the Pelagos Sanctuary for Mediterranean Marine Mammals. This sanctuary includes both national and international waters. Both the CBD and IUCN recommended a variety of management systems for use in a protected area system. They advocated that MPAs be seen as one of many "nodes" in a network of protected areas. The following are the most common management systems: Seasonal and temporary management—Activities, most critically fishing, are restricted seasonally or temporarily, e.g., to protect spawning/nursing grounds or to let a rapidly reducing species recover. Multiple-use MPAs—These are the most common and arguably the most effective. These areas employ two or more protections. The most important sections get the highest protection, such as a no take zone and are surrounded with areas of lesser protections. Multiple-use MPAs can make use of very diverse fisheries regulations to balance fisheries extraction with nature protection. Community involvement and related approaches—Community-managed MPAs empower local communities to operate partially or completely independent of the governmental jurisdictions they occupy. Empowering communities to manage resources can lower conflict levels and enlist the support of diverse groups that rely on the resource such as subsistence and commercial fishers, scientists, recreation, tourism businesses, youths and others. Mistrust between fishermen and regulating authorities is of central importance there, and needs to be addressed. Recent evidence from regions like Scandinavia, Spain, Portugal or Canada reveals success stories based on the tested cooperation between marine scientists and fishermen in jointly managing coastal marine reserves. Marine Protected Area Networks Marine Protected Area Networks or MPA networks have been defined