Aquaculture methods used off the coast of Puerto Rico, in which deepwater cages raise species of fish in the open ocean, provide alternatives to some of the destructive techniques of industrial fishing.
Skerry also traveled to New Zealand and photographed the success story of a marine reserve called Goat Island. In the 1970s, a species of fish called the New Zealand Snapper was on the brink of extinction, so the government set aside an area that was untouchable to fishermen and even scientists. A few decades later, the ecosystem is thriving, and hundreds of thousands of tourists visit every year.
"I saw a great abundance, great diversity, healthy ecosystems, lots of fish," Skerry said. "So I felt there was some hope."
After traveling the globe and studying the seas, and swimming with the Bluefin tuna, Skerry knows the oceans are in a serious state. But giving those on land a window into the world undersea, he said, is a step in helping people understand what's at stake.
"If we could communicate the bad news to people, and then show them some solutions, then maybe, maybe there would be some hope in the end."