Photo: Greg Nichols

In the past few decades, overfishing—coupled with climate change and pollution—has crushed our oceans' delicate ecosystems. In 2010 the United Nations estimated that 85 percent of the world's fish were overexploited or being fished at maximum levels. Which raises the question: What's a sushi lover to do?

She could start by heading to Portland, Oregon, where Kristofor Lofgren, 30, is pioneering a guilt-free way to indulge in omega-3s. At Lofgren's acclaimed restaurant, Bamboo Sushi, you won't find overfished sushi-roll staples like bluefin tuna or unagi—but you might find sustainably caught Tasmanian ocean trout, horse mackerel, or even cod sperm. An inventive "Bamboo charcuterie plate" features "blood sausage" made from local Pacific albacore tuna. Lofgren's meticulous sourcing from only healthy populations has earned his restaurant the first Marine Stewardship Council certification in the United States.

In his view, sustainability is more than a gimmick."Fish caught with care, in a more artisanal fashion"—e.g., using low-tech traditional methods like rods or a small net—"taste better," he says. "In a massive net, all the fish are struggling and stressed-out," conditions that raise the fishes' cortisol levels, which can make their meat tougher. Lofgren's hope is to lure customers with his sushi, then hook them through education. To that end, he's offering a whole shark on the menu—for adoption (the price: a $4,000 minimum donation to the University of Miami's marine conservation program, after which the restaurant will fly you to Florida to personally tag your toothy pet). "Being sustainable doesn't just mean sticking to seafood that's caught ethically and not overfished," Lofgren says. "Our goal is to turn our customers into ambassadors."