Barton Seaver apologized, but he had to cut our interview short. He and his wife, Carrie Anne, had reservations that evening for Bistro Bis, just the latest restaurant he wanted to visit before leaving his hometown and the city where he made his name.

Barton Seaver, back in his sustainable chef days at Hook in Georgetown. (Marvin Joseph/The Washington Post)

In two weeks, Seaver will be saying goodbye to Washington to lead the Healthy and Sustainable Food Program at the Center for Health and the Global
Environment within the Harvard School of Public Health. Yes, as a job title, it's rather daunting. Then again, so is his job: to improve public and environmental health by weaning us off unsustainable and mercury-laden seafood.

Seaver will be moving into a full-time position at the school to expand his role in seafood conservation and public health. The chef and author of "For Cod and Country" had already been working with the Center for Health and Global Environment to develop guidelines that will assist hospitals, universities and other large institutions in purchasing sustainable seafood. He's also paired with the center and National Geographic, where he's been a fellow since 2010, to create the Seafood Decision Guide, which provides consumer information on fish that are sustainable, high in mercury and/or rich with omega-3 fatty acids.

"We have just found an opportunity to expand beyond the work that the center was already doing with food," Seaver says during a phone conversation.  He says he will not only serve as a seafood resource for Harvard students, but will also work closely with three institutions on their sustainable seafood purchases, with the goal of creating a "blueprint," which other large-scale companies can adopt and adapt for themselves.

"So any institution, any food-service operator anywhere, can pick up this packet and create their own goals" about sustainable seafood, Seaver says, "then move through the whole process."

Why go after hospitals and universities and the like? As Seaver noted in a recent news release, it's all about volume and influence: "Hospitals, like other large institutions, can shift food systems away from conventional methods by leveraging their enormous purchasing power and increasing demand for more sustainably managed produce, meat and seafood,” he said.

If that weren't enough, last fall Seaver became the first-ever "sustainability fellow in residence" at Boston’s New England Aquarium. So how will his aquarium gig differ from the ones he has with Harvard and Nat Geo?

"In very important ways that are hard to describe," Seaver deadpans. Essentially, he says, his sustainability fellowship at the aquarium will focus on the fishing industry and supply chain, looking for ways to improve the practices of producing and distributing fish. His work with Harvard and National Geographic will focus mostly on consumers and other end users.

Amid all his sustainability work, Seaver has not lost touch with his first love: cooking. His second cookbook, the grill-oriented "Where There's Smoke," is due out in April from Sterling Epicure. The volume, of course, comes with more sustainability and healthful-eating messages. The forthcoming release made me wonder if the former Hook chef misses working in restaurants, which he last did at the now-shuttered Blue Ridge in Glover Park, where he earned Chef of the Year honors in 2009 from Esquire despite lackluster reviews from local critics.

"My passions have evolved so much to the point that I would be doing myself a disservice if I were in a restaurant," Seaver says, "and I would be doing the restaurant a disservice, since my attention would not be there.”

But he says he will miss his hometown: "There are a lot of things about D.C. that we'll miss terribly, like Vace's onion pizza for one," Seaver says. "And any article of food touched by Frank Ruta” at Palena.