<Tr> <Td> </Td> <Td> This article contains weasel words: vague phrasing that often accompanies biased or unverifiable information . Such statements should be clarified or removed . (July 2015) </Td> </Tr> <P> Along the mediterranean regions of the Arabian Sea, including the Persian Gulf, the Red Sea, the Gulf of Kutch, the Gulf of Suez, the Gulf of Aqaba, the Gulf of Aden, and the Gulf of Oman, dolphins and finless porpoises are the most common marine mammals in the waters, while larger whales and orcas are rarer today . Historically, whales had been abundant in the gulf before commercial hunts wiped them out . Whales were reduced even further by illegal mass hunts by the Soviet Union and Japan in the 1960s and 1970s . Along with Bryde's whales, these once common residents can still can be seen in deeper marginal seas such as Gulf of Aden, Israel coasts, and in the Strait of Hormuz . Other species such as the critically endangered Arabian humpback whale, (also historically common in Gulf of Aden and increasingly sighted in the Red Sea since 2006, including in the Gulf of Aqaba), omura's whale, minke whale, and orca also swim into the gulf, while many other large species such as blue whale, sei, and sperm whales were once migrants into the Gulf of Oman and off the coasts in deeper waters, and still migrate into the Red Sea, but mainly in deeper waters of outer seas . In 2017, waters of the Persian Gulf along Abu Dhabi were revealed to hold the world's largest population of Indo - Pacific humpbacked dolphins . </P> <P> One of the more unusual marine mammals living in the Persian Gulf is the dugong (Dugong dugon). Also called "sea cows", for their grazing habits and mild manner resembling livestock, dugongs have a life expectancy similar to that of humans and they can grow up to 3 metres (9.8 feet) in length . These gentle mammals feed on sea grass and are closer relatives of certain land mammals than are dolphins and whales . Their simple grass diet is negatively affected by new developments along the Persian Gulf coastline, particularly the construction of artificial islands by Arab states and pollution from oil spills caused during the "Persian Gulf war" and various other natural and artificial causes . Uncontrolled hunting has also had a negative impact on the survival of dugongs . After Australian waters, which are estimated to contain some 80,000 dugong inhabitants, the waters off Qatar, Bahrain, UAE, and Saudi Arabia make the Persian Gulf the second most important habitat for the species, hosting some 7,500 remaining dugongs . However, the current number of dugongs is dwindling and it is not clear how many are currently alive or what their reproductive trend is . Unfortunately, ambitious and uncalculated construction schemes, political unrest, ever - present international conflict, the most lucrative world supply of oil, and the lack of cooperation between Arab states and Iran, have had a negative impact on the survival of many marine species, including dugongs . </P> <P> The Persian Gulf is also home to many migratory and local birds . There is great variation in color, size, and type of the bird species that call the gulf home . One bird in particular, the kalbaensis subspecies of the collared kingfishers is at the brink of extinction due to real state development by cities such as Dubai and countries such as Oman . Estimates from 2006 showed that only three viable nesting sites were available for this ancient bird, one located 80 miles (129 km) from Dubai, and two smaller sites in Oman, all of which are in the process of becoming real estate developments . Such expansion would prove devastating and could cause this species to become extinct . Unfortunately for the kingfisher, a U.N. plan to protect the mangroves as a biological reserve was blatantly ignored by the emirate of Sharjah, which allowed the dredging of a channel that bisects the wetland and construction of an adjacent concrete walkway . Environmental watchdogs in Arabia are few, and those that do advocate the wildlife are often silenced or ignored by developers of real estate, most of whom have royal family connections and huge energy profits to invest . The end result has been sacrifice of a beautiful yet delicate ecology that has been in harmony for hundreds of years, for structures that are erected only a few years, yet will have a lasting detrimental effect . </P>

What has happened to the coastline of the persian gulf over time