It’s no secret. One glance at the shimmering sardine on the cover of Andy Sharpless’s new book The Perfect Protein reveals that the answer is simple: “We need to eat fish and lots of it . . . .”

It’s not a new message. “We all know fish are good for your brain, your heart and your nerves,” said Mr. Sharpless. “If you substitute fish for red meat, you get a reduction in obesity, heart disease, cancer. It’s interesting how our own biology is so tuned up to benefit from fish.”

But here’s the catch, he added. “It’s not just any fish.”

On Tuesday evening, Mr. Sharpless gave a reading at the Bunch of Grapes Bookstore in Vineyard Haven. In addition to being a writer, Mr. Sharpless is the CEO of Oceana, an international conservation organization dedicated to protecting the oceans.

During his talk Mr. Sharpless outlined a healthier, sustainable and more economically efficient way of approaching the maritime production industry. His book, cowritten with Suzannah Evans, provides a clear and digestible expose on why fish are so great, why they should be protected, the inefficiencies of the process in place today and how readers can help revolutionize the way we approach fish consumption.

With the predicted population of our Earth expected to reach nine billion by 2050, the growing demand for food products puts an enormous strain on the agricultural sector of the world economy. Only 29 per cent of the Earth is land, and an even smaller portion of that land is arable.

“Agriculture, much more than urbanization and even timbering, is the fundamental driver of deforestation and biodiversity loss on the planet. Cattle and all other forms of livestock are fed enormous amounts of grain . . . Wild fish on the other hand don’t eat any grain,” Mr. Sharpless said. The earth’s aquatic surface is still an abundant source of wild protein.

However, increased consumption does not imply that less care should be taken regarding the fishing and marine product industry. We have to both protect marine life and biodiversity while keeping up with an increase in demand for food and protein in our staggeringly rising population, Mr. Sharpless said.

“Think of it as an investment. You put money in the bank to get interest and increase its net worth, which you then use later. It’s the same concept with fish. We have to save fish, to eat fish.”

So how does one reconcile the well-advertised hazards of overfishing with Mr. Sharpless’s omega-rich diet? Wild fish populations have been in decline over the past 10 years due to three primary factors: overfishing, bycatch and destruction of habitat. “But not eating fish isn’t the way to respond to overfishing,” he said. “Building an abundant ocean is easier and more achievable than people realize. The truth is, we’ve been misled by some of the most charismatic creatures in the ocean. When we think of fish we think of tunas, sharks, Atlantic salmon, but these are just the lions and tigers of the ocean world.”

Instead of buying a piece of swordfish, readers are encouraged to seek smaller specimen of fish, such as anchovies, sardines, mussels and clams.

“What people don’t realize is that we are grinding up small “reduction fish such as anchovies, mackerel and sardines into feed for salmon and other farmed animals even though these overlooked fish are delicious and packed with health-boosting omega-3 fatty acids, and could feed millions inexpensively.”

According to Mr. Sharpless, if only 25 coastal nations, including the United States, take three simple steps to improve their seafood supply industries, the world’s oceans will experience a rise in levels of biodiversity and an increase in the number of fish available for public consumption. The steps are stop overfishing, control bycatch and protect fishing nurseries. By improving how the marine industry is managed, we reap subsidiary benefits that affect personal health, take pressure off of the agricultural industry and even reduce carbon emissions, he said.

“It seems self-evident when you think about it, yet so few people are aware of the potential fish have as a sustainable protein. That’s why I wrote this book . . . to inform and provide a practical guideline to get our mission going.”

He also provides tips for the consumer. “I’d summarize them like this: look for wild and local fish as well as farmed mussels and clams. Other farmed varieties of fish on the other hand, your salmon, tuna, and swordfish, are not so great. And unfortunately there’s no sustainable way to eat shrimp, wild or farmed. I know its tragic, I love them too.”

The book includes recipes from 21 world-renowned chefs. The author’s personal favorite is “Eric Ripert’s Clams with Spicy Sausage. I’m not the best cook so I didn’t know whether I could manage it, but I definitely surprised myself.”