As wild populations falter, aquaculture will be essential if we want to eat seafood in the decades to come. So it's more important than ever to find ways to do it like Michael Passmore does—better, cleaner and more efficiently.

Carolyn Jung
September 17, 2019
California has lost as much as 90% of its wetlands, areas that improve water quality and provide essential habitats. The lakes Michael Passmore (shown here) dug on his fish farm not only hold sturgeon and other fish, they are home to a wide range of plants and wildlife, including nesting osprey and eagles.
Marc Olivier Le Blanc

The dust settles as Michael Passmore brakes to a stop on a dirt road that cuts through his 84-acre fish ranch on the edge of Northern California's Sierra foothills. He bounds over to an aboveground pool where 50 sturgeon swim, each about 6 feet long and 100 pounds. The fish are part of Passmore Ranch's brood stock—mature fish used for breeding. After inspecting them, he steps into a corrugated steel gazebo that encloses a hatchery. Baby fish 2 inches long shimmy in tubs of recirculating water. When they get bigger Passmore will transfer them to one of seven 6-foot-deep lakes he dug that dot his property. The fish will remain there until they reach market size and are sold to some of the finest restaurants in the country.

In 2005, Passmore couldn't find a single loan to develop the farm. After all, he had no farming experience. But that didn't stop the now-47-year-old former Marine. Through a decade of scorching summers and dank winters, he and his wife lived on the property in an RV as he built infrastructure, installed electricity and moved 300,000 cubic yards of dirt. "In the beginning, I hauled our water in, we ran a generator a few hours a day, and I hauled our septic out," Passmore says. "It was not for the faint of heart.''

Related: Jellyfish, Anyone? How Warming Oceans Will Change What We Eat

Humans consumed an estimated 333 billion pounds of fish in 2016, according to a United Nations report. And each year that amount is increasing, at an even faster rate than the population is growing. Meanwhile the global catch of wild seafood has stayed relatively flat since the 1980s. This is in large part due to the fact that over a third of wild fish populations are overfished and more than half are fished at their maximum sustainable level. Seafood raised on farms, aka aquaculture, is filling the gap between the increasing demand and the limited supply of wild fish. And aquaculture is set to be our largest source of seafood in 2020. A 2018 report from the Food and Agriculture Organization of the United Nations shows that global fish production reached 171 million metric tons in 2016, with 47% coming from aquaculture. By 2020, aquaculture will be producing more fish than all wild fisheries (including fish for nonfood use).

But there's an ugly side of aquaculture—questionable practices have led to problems like coastal habitat destruction, polluted waterways and unwanted escaped species. (See "Aquaculture: 3 Ways," below, for more on different methods of farming seafood.) But the industry is making considerable strides. "There are now good examples for most farmed species out there,'' says Ryan Bigelow, senior program manager for the Monterey Bay Aquarium's Seafood Watch program.

Passmore Ranch is one such model of a better way to cultivate fish. Sturgeon, catfish and carp are raised in its landlocked lakes and tanks, eliminating the risk of escapees invading other bodies of water. A water-treatment system removes waste (mostly uneaten food and fish feces) and allows the water to be used up to seven times. "Our goal is to utilize each drop of water as many times as possible," Passmore says. And, perhaps most important, the ranch's feed is largely plant-based: only 15% of it is fishmeal from scraps left over from processing wild and farmed fish. Usually fishmeal comes from wild fish, typically small species but ones that are essential nonetheless because they form the foundation of the marine food web.

Unfortunately, Passmore's operation is not a universal solution for farming fish sustainably. Take bluefin tuna, one of the most overfished species in the world. Bluefin typically live 15 to 30 years, average 61/2 feet long and weigh in at about 550 pounds. Some are farmed in marine net pens, but imagine the scale of an operation needed to raise them in ponds or tanks. Not only that, while Passmore's fish are healthy on their mostly plant-based diet, farm-raised bluefin need an average of 20 pounds of feed, mostly wild fish, to gain just 1 pound.

According to Ethan Lucas, project director for FishWise, a Santa Cruz-based nonprofit that works with businesses to foster marine conservation, Passmore really stands out from the pack. FishWise has partnered with Passmore since 2010 because "They are being innovative and finding ways to produce species that are popular or niche and creating a demand for them," says Lucas. "It is seafood raised with environmental stewardship in mind.''

Chefs at more than 400 restaurants across the country, including the likes of Thomas Keller and Alex Guarnaschelli, feature Passmore's fish on their menus. Joey Elenterio, owner of French Fries & Caviar Consulting, is a fan of Passmore's catfish in particular. "Often, we think of catfish as a muddy-tasting fish. His is so clean and distinct. He won me over," Elenterio says. "Ever since I tried it, I've been a believer in Passmore Ranch."

Walking around the farm, it's clear that Passmore is passionate about his operation. He's planning to add a 4,000-square-foot caviar-production facility in the months to come. Eventually, he wants to plant vineyards and orchards and to build an aquaponics system to grow vegetables that will be fertilized by the nutrient-rich water from the fish lakes. "Folks ask me all the time what I'd do if this all went up in flames," Passmore says. "I'd build it all over again."

Read more: 5 of the Healthiest Fish to Eat (and 5 to Avoid)

Aquaculture: 3 Ways

by Clare Leschin-Hoar

Marine Pen

What it is: A cage, usually made of wire or synthetic material like nylon, that corrals fish in the ocean.

Species: Salmon, yellowtail, branzino (European sea bass)

Benefits: New net-pen farms are sited in locations with strong currents and rocky bottoms so waste is more easily dispersed. To combat sea lice—tiny parasites that harm farmed and nearby wild salmon—fish farmers are using small fish called lumpsuckers (which nibble sea lice off salmon), warm-water baths and even lasers. The result: fewer pesticides are needed. And vaccinations, lower stocking densities, fish stocks bred for better disease resistance, and adding probiotics to the fishes' diets have reduced reliance on antibiotics.

Future outlook: Integrated systems might include a marine pen stocked with salmon, surrounded by ropes of mussels and sheets of seaweed, both which can absorb excess nitrogen and phosphorus from fish feed.

Tank System

What it is: Connected tanks, typically indoors, with filtered water continuously flowing from one tank to another; also known as a recirculating aquaculture system.

Species: Sturgeon, striped bass, steelhead trout, salmon, yellowtail, turbot, Arctic char, branzino and tilapia

Benefits: Self-containment means fish can't escape, plus pollution and habitat destruction are minimized. As much as 98% of the waste—like uneaten food pellets and fish feces—can be captured. Depending on the type of treatment system, water can be reused up to 1,000 times.

Although these systems are energy-intensive, they can be located close to an urban populations so the fish won't have to travel as far to our plates, offsetting some of its carbon footprint.

Future outlook: By 2030, up to 40% of the world's aquaculture products may be grown in tanks.

Pond

What it is: A natural or man-made fresh- or saltwater pond.

Species: Shrimp, tilapia, catfish, pangasius, black and striped bass, silver carp and white sturgeon

Benefits: Older ponds were designed to be open to rivers, estuaries or coastal zones for easy access to fresh water. But today's improved ponds use "closed system" designs that prevent both pollution discharges and farm-raised species from escaping. Advances in water filtration remove waste and chemicals (like fertilizers or antibiotics), and recirculating systems allow farmers to reuse water. Adjacent treatment or settlement ponds safely keep waste out of nearby water sources.

Future outlook: Pond aquaculture had been one of the leading causes of coastal mangrove loss. Mangrove trees are important because they trap carbon and reduce flooding and erosion. Countries including Ecuador, India, Indonesia, Thailand and Vietnam have recently enacted stronger laws to protect them from further devastation.

Click through for more stories about the Future of Food.

October 2019 EatingWell
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