There are no quick fixes to managing the complex Atlantic bluefin tuna fishery.

These slow growing but lightning fast fish are highly migratory, which can distort regional stock assessments. Changing ocean water temperatures in the wake of climate change means that where these predators can find enough food to support their 500-pound bodies is also changing.

The age at which fish reach sexual maturity can vary up to six years, making it difficult to assess how stocks will rebound after overfishing. And the type of gear used to catch Atlantic bluefin tuna ranges from simple harpoons to multiple drifting longlines, a fact that divides the fishery into a dizzying array of subcategories.

“The only predictable thing about the management of Atlantic bluefin tuna is that it is very unpredictable,” said Walt Golet, assistant professor in the School of Marine Sciences at the University of Maine and researcher at the Gulf. of Maine Research Institute, or GMRI.

Golet pointed out, for example, a report on the 2020 stock assessment released in March 2021 by the National Oceanic and Atmospheric Administration which indicated that a reduction in quotas might be justified – meaning fishermen would be allowed to catch. less bluefin tuna. But in just four months since the report was released and after questions about its findings, the federal government has agreed to do another assessment. Separately, regulators and scientists are working on new assessment models that will allow them to target different rebuilding requirements, such as management for immediate maximum yield or management for long-term harvest, when drafting ” a fisheries management plan.

Golet’s research aims to understand the whereabouts of bluefin tuna caught in the Gulf of Maine before they arrived here. Atlantic bluefin tuna usually arrive here in early June and stay until September, although a few stay until early winter.

Golet is working with a network of fishermen to understand how bluefin tuna tap into North Atlantic habitats for food and growth. Fishermen provide data on the size of the fish, and when and where they were caught. In addition, Golet and his students take tissue samples for DNA analysis from a smaller number of fish and extract their otoliths, small bony structures in the fish’s head. Just as growth rings record information about the life of a tree, otoliths record information about the life of fish. Combined, DNA analysis and data from fishermen provide Golet’s team with a complete picture of where the fish were born, their overall health and eating habits.

This information is important for the management of the bluefin tuna fishery because Atlantic bluefin tuna stocks have always been controlled based on the origin of the fish, and research has already shown that Atlantic bluefin tuna East and Mediterranean is in better shape than those of the West Atlantic. But the DNA and otoliths studied by Golet indicate significant levels of mixing between eastern and western bluefin tuna, a finding that could further alter the way management parameters are set in the future.

Despite the challenges, regional, national and international regulators manage bluefin tuna fisheries, as eaters around the world have a great appetite for bluefin tuna, which is a popular substitute for sushi. Given the pressure of consumption, sustainable seafood guides like the Monterey Bay Aquarium’s Seafood Watch tell consumers to completely avoid bluefin tuna, no matter where it is caught, and instead opt for other types of tuna, such as skipjack and yellowfin.

So what should a sustainable seafood eater in Maine do when presented with locally caught Atlantic bluefin tuna?

“When caught by fishermen in Maine, this is a really special seasonal seafood product, and we are fortunate to have it,” says Kyle Foley, Senior Manager of the Sustainable Seafood Program at GMRI . His sentiment is echoed by some chiefs in Maine.

“The Atlantic bluefin tuna… has absolutely had a renaissance due to the strict regulation and control of the harvest,” said Jesse Souza, Executive Chef of Front & Main at Waterville. “This settlement brought our local bluefin tuna back and established it as a sustainable product that we can feel good to have in our kitchens and on our plates.” Souza buys her bluefin tuna from Harbor Fish in Portland and believes the fish should be treated simply in the kitchen to showcase its natural combination of fat, salinity, and melt-in-your-mouth texture.

Kirby Sholl, chef at Chaval in Portland, says he enjoys working with bluefin tuna because it can resist big flavors like chili peppers, soy sauce and wasabi. He knows that when he receives an order from fishmonger Browne Trading and puts it on the menu, it will sell, a point no chef can take lightly as restaurants struggle to recover from pandemic losses. But he also serves him because he trusts Maine fishermen, who have in the past signed up to measures – some mandatory, others voluntary – to protect future stocks of other popular seafood like cod. , halibut and lobster.

As the regulations currently stand, commercial vessels licensed to fish in the Gulf of Maine can take three bluefin tuna per fishing trip until the national quota for them is reached each year. Despite the low cap, fishermen in Maine are ready to fish for bluefin tuna as a single fish can sell for up to $ 15,000. The retail price of bluefin tuna in Portland is between $ 20 and $ 40 a pound.

Making sure that no big tuna is wasted is one way for consumers to make sure their choice is a sustainable act, said Jen Levin, president and CEO of Gulf of Maine Sashimi, a fish supplier in Portland. . In the height of the season, she plans to turn around three bluefin tuna per week into cuts of loin, belly and belly fat, which she sells to restaurants and directly to customers through the company’s website. Chefs can also order special cheeks and tails. So if you see Maine bluefin tuna on a restaurant menu, you can be sure you can eat it.

Christine Burns Rudalevige is a food writer, recipe developer, tester and cookery teacher in Brunswick, and the author of “Green Plate Special”, an Islandport Press cookbook based on these columns. She can be contacted at: [email protected]

Drizzle the tuna skewers on the grill with a spicy Asian-inspired marinade. Ben McCanna / Personal Photographer

Hot and sweet tuna skewers and melon salad

This recipe will work with any meaty fish, including bluefin and yellowfin tuna, shark, swordfish, and dogfish.

For 4 people

FOR KEBABS:
2 (3/4 pounds) raw tuna loin
3 tablespoons of olive oil
2 tablespoons of honey
2 tablespoons of soy sauce
1 tablespoon of grated ginger
1 tablespoon of Asian chili garlic sauce
1 teaspoon ground allspice
4 wooden skewers, soaked in water for an hour
1 tbsp sesame seeds, for garnish

FOR THE SALAD:
Zest and juice of 1 lime
1 tablespoon of soy sauce
1 tablespoon of fish sauce
1 teaspoon of honey
1 teaspoon of sesame oil
1 teaspoon minced fresh Fresno pepper
4 cups scoops of watermelon, honeydew and cantaloupe mixed together, in 1-inch pieces
1/4 cup cilantro leaves
1/4 cup chopped green onions
3 tablespoons pickled ginger, coarsely chopped

Cut each of the tuna loins into 8 pieces of similar size.

In a medium bowl, combine olive oil, honey, soy sauce, ginger, garlic, and chili sauce and allspice. Transfer half of the marinade to a small bowl and set aside. Toss the tuna pieces with the remaining marinade in the medium bowl. Place in the refrigerator to marinate for 30 minutes.

To cook the tuna, thread 4 pieces of marinated fish onto each skewer. Preheat a grill to medium-high heat. Place the skewers on the grill. Cook on the first side for 2 minutes. Turn the skewers to cook on each next side for 1 minute. A total cooking time of 5 minutes will make the tuna pieces perfect. Remove from the grill and brush with the reserved marinade and sprinkle with sesame seeds.

To make the salad, combine lime zest and juice, soy sauce, fish sauce, honey, sesame oil and chili. Add the melon, cilantro, green onions and pickled ginger. Toss to coat the melon with vinaigrette and serve with the tuna skewers.

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