The world’s oceans need protection, a globe-traveling National Geographic underwater photographer told a large audience at the Tabernacle last Saturday.

After 35 years of photographing the oceans, Brian Skerry, 49, said he is troubled by growing evidence of degradation of habitat and the waste and loss of sea life. “I think the oceans are dying a death of a thousand cuts,” he said.

The photographer gave more than a one-hour talk called Window to the Sea, sharing beautiful and illustrative pictures of the ocean bottom, coral reefs, sharks, small bait fish and large whales.

The audience of over 400 people oohed and ahhed as the pictures flashed up on the screen. But in addition to offering a vivid photography show, Mr. Skerry advocated for better management of the earth’s oceans.

“Unless you are diving, unless you know what is going on beneath, you don’t see all the problems,” he said. “[The ocean] is suffering from acidification, from overfishing, pollution . . . All of these things are combining. And most of this is out of view.”

He added: “As a journalist, I felt it was incumbent on me to tell these stories, not just show the pretty pictures but to show what is going on.”

The presentation by the photographer was not about shutter speeds or f-stops or how to take a picture underwater. Rather it was a direct account from a man who dives in the oceans, and who has seen the bottom from New Zealand to the cold waters of the Arctic. He spoke of talented scientists he had met, people who had taken on a mission to make a difference in their communities, of those who work and live by the sea. His story about the beauty and troubles of the ocean was illustrated with a collection of pictures of unique and different places. His remarks were infused with concern about the future and also hope that some action can be taken to change the current direction.

“Most of my work is both celebratory pictures of the ocean, but it is also about some of the issues, too,” Mr. Skerry said.

He showed wonderful tranquil pictures of schools of fish swimming together and of solitary, menacing sharks. He showed close-up shots of the eye of a right whale in the North Atlantic and another in the South Atlantic. He warned that in the last few years fishing effort on a wide variety of sharks may have a far greater impact on the balance of nature than earlier thought. He said fishermen are decimating some species. He showed a picture of the oceanic white-tip shark, a solitary animal once abundant in warm waters but sadly now scarce.

He showed the impact gill nets can have on large, rare fish. He expressed concern about the indiscriminate and devastating impact of long lines on marine mammals. He warned that the use of nonselective dragger nets with their destructive doors scraping on the bottom can cause widespread damage to bottom habitat. Mr. Skerry said there are other ways to catch fish without sacrificing valuable ocean bottom. To illustrate the story, he showed photographs of a shrimp fishing boat working in the waters off La Paz, Mexico, where the water quality is pristine. The photograph showed the dragger door sliding along the bottom leaving a disturbed path. “It is like clear cutting a forest,” Mr. Skerry said.

Mr. Skerry took the story a step further by showing the results of what the net caught. The commercial fisherman, after dragging for a time, only harvested five large shrimp, discarding many other fish killed in the effort.

“We’ve lost so much,” the photographer told the rapt audience.

He ended the talk on a positive note, featuring the marine sanctuary established at Goat Island in New Zealand. He spoke about Bill Ballantine, a mollusk scientist, who chose to set aside a wasteland beach and waterfront as a sanctuary because he believed that if man left it alone in 1972, it would flourish. “He had to fight everyone — sport fishermen, commercial fishermen and scientists,” Mr. Skerry said.

Mr. Ballantine’s efforts were so successful the sanctuary has become a model and subject of discussion among scientists around the world. The site had become a wasteland because fish like snapper were depleted. But once the snapper were left alone, they began to eat the sea urchins. The sea urchins ate the kelp. In a short time, the waters became abundant with all kinds of fish. The natural balance of underwater species returned. “This is probably a place that looks just as it did 100 years ago,” Mr. Skerry said.

He concluded: “When you take the fishing away, you are creating places where the ocean can come back to a level of equilibrium. Now there are 300,000 people who come to wade in the water [at Goat Island] and look at the fishes. The message is clear.”

He also said: “The ocean represents so much of our earth. Though we are terrestrial creatures, it is the ocean that gives us life. Four out of five breaths taken by a human comes from the ocean. The ocean produces the oxygen. Ninety-eight per cent of the earth’s biosphere is oceans. We often think that the oceans represent three quarters of the surface of the earth, but look at the volume where animals live and it is 98 per cent.”

Mr. Skerry came to the Vineyard to give the talk at the invitation of a Camp Ground resident. He lives in Uxbridge and said he grew up swimming from Cape Cod beaches. His first shoot for National Geographic was of the pirate ship Whydah 13 years ago.

His newest book, Ocean Soul, will be formally released in November and is available at