Editor 's note : Ted Danson is an Emmy Award-winning actor , a founding board member of Oceana , the world 's largest international organization dedicated solely to ocean conservation , and narrator of a new film , `` End of the Line . '' For more information about Oceana , read here . Ted Danson says a `` closed '' sign on a beach led him on a 20-year quest to save the world 's oceans . ( CNN ) -- Today , Monday , June 8 , we recognize the first U.N.-sanctioned World Oceans Day . The event comes after years of pressure from conservation groups and thousands of activists who clamored for everyone to know and understand what 's happening in our oceans . I became an ocean activist in 1987 . It was the fifth year of `` Cheers '' and my family moved into a neighborhood that was on the water , in Santa Monica , California . One day I took my daughters to the beach to go swimming , but it was `` closed '' and I could n't answer my daughter 's question why . That 's really how it started . That and `` Cheers '' was paying me a lot of money and I felt I had better be responsible with it . So , I started to get involved . It turned out in our new neighborhood there was a fight to keep Occidental Petroleum from drilling 60 oil wells on Will Rogers State Beach in Los Angeles . They wanted to slant drill into the Santa Monica Bay . The fight was led by a man named Robert Sulnick and we became great friends and found a way to beat them . We enjoyed ourselves so much that we wanted to continue this work . So Robert Sulnick and I , full of passion and naiveté , started American Oceans Campaign , which ultimately became a part of Oceana . And , here I am , still at it , 20 years later -- because our oceans are in trouble . Watch Danson talk about his commitment to save the world 's oceans » . The U.N. reports that 75 percent of seafood species are maxed out or overexploited and catches of nearly a third of these species are less than 10 percent of what they once were . Ninety percent of the big fish -- sharks , tuna , swordfish -- are already gone , according to a 2003 study in Nature . The chemistry of the oceans is changing as they absorb 11 billion metric tons of carbon dioxide a year , and scientists say the acidifying waters will make it impossible for coral reefs , the nurseries of the sea , to grow . At the current rate of acidification , corals , sea snails and other calcium-carbonate-requiring life forms could begin to dissolve by the middle of the century , with potentially catastrophic results . Shellfish and fish will be in deep trouble as well . This is all happening on our watch . My friend Charles Clover , then a reporter for the U.K. 's Telegraph , wrote an incredible book about all of this called `` The End of the Line '' that lays out , in devastating detail , how this has happened . The book is now a film , released today , and I 'm honored to serve as the narrator . The movie describes how marine scientist Daniel Pauly ( a fellow Oceana board member ) discovered China had been falsifying its fish catch data , and that instead of increasing , global fish catch had actually peaked in the late 1980s at about 80 million tons a year and had been falling ever since , despite better and faster technology and billions of dollars in government subsidies . The film also describes how we are about to fish one of the most magnificent fish in the ocean , the bluefin tuna , into extinction . It 's not the only one we 're eating into oblivion . Cod , once a staple in the working man 's lunch of fish and chips , is increasingly a delicacy . Unable to catch once-prized species , fishermen are selling creatures that you would never have considered eating , like the once-disdained skates that replace scallops on European tables . Even jellyfish are becoming a commercially viable species . World Oceans Day is an opportunity to bring these underwater challenges to light . And it 's a chance to explain how we can restore our oceans to their former glory . Ocean conservation is rewarding because you absolutely can make a difference . You leave a fish population alone for a while , and it rebounds . The oceans are incredibly resilient . We have the opportunity right now to protect the oceans and the life they harbor for future generations . By protecting important habitats like corals from destructive fishing techniques , and setting science-based quotas on seafood species , the battle is halfway won . Fish species will recover , and the marine mammals , sea turtles and seabirds that rely on them for sustenance have a fighting chance . In addition , we must commit to renewable energy sources to end the excessive carbon dioxide emissions that are acidifying the oceans and making them inhospitable to life . The ocean does represent a source of energy , and it 's not offshore oil and gas drilling -- it 's offshore wind . Europe is a leader in developing offshore wind power , and it 's time for the United States to catch up . Today , on World Oceans Day , do n't just go green . Go blue . The opinions expressed in this commentary are solely those of Ted Danson .
Ted Danson : June 8 is the first U.N.-recognized World Oceans Day . He says oceans are in trouble with 75 percent of seafood species in danger . Saving oceans is doable if we allow fish species to rebound , Danson says .