Irish seafood chowder was my go-to pub lunch after mornings of walking the paths connecting the small cities and towns in western Ireland all of September. Piping hot bowls of the soup were widely available, generally filling and typically delicious. But I rarely got the same combination of seafood in the chowder twice.

Depending on the cook, all sorts and combinations of seafood “swam” in the creamy base, including flavorful Finnan Haddie (cold smoked haddock); flaky white fishes; pink Atlantic salmon; squid from Galway Bay; prawns pulled from the sea near Dublin; mussels from nearby Killary Fjord, sometimes still in their shells; or even small scallops, with their roe intact.

I took what I got, and I ate it all with enthusiasm. The assortment, though, had me wondering which seafood was wild caught and which was farmed. The odds were three to one in favor of the former, I learned. In 2022, according to Bord lascaigh Mhara, Ireland’s seafood market development agency, the value of the Irish seafood sector stood at €703 million (about $774 million), with the value of Irish aquacultural products comprising about 28 percent of that total.

Numbers aside, Irish fishing fleets face many of the same issues that Maine ones do. Both contend with depleted stocks and decreasing catch limits, warming waters and erratic weather patterns caused by climate change, and fluctuating fuel costs and stagnating catch prices due to geopolitical factors over which fishermen have no control.

And, as in Maine, the interest in sustainable aquaculture in Ireland is on the rise. The Irish seafood industry is exploring many possible ways to develop finfish, shellfish and seaweed aquaculture as a productive, environmentally sound and cost-effective way to sate Europe’s longstanding appetite for seafood.

One avenue under exploration is what’s known as integrated multi-trophic aquaculture (IMTA). In this type of set up, multiple species that live in different parts of the water column (called trophic levels) are farmed together, as a potential way to reduce pollution caused by salmon farming. Scientists want to see if by farming many species together, they can improve efficiency, reduce waste, and provide ecosystem services like bio-remediation, which is when one species naturally cleans up the biological mess created by another species.

In an IMTA system, plants, shellfish and invertebrates that grow on sunken long lines and suspended baskets consume food waste and feces from finfish (usually salmon) pens that sit just below the water’s surface. The fish farmers can then harvest and sell the salmon, and also the plants, shellfish and invertebrates.

After a particularly grueling hike up 2,507-foot Croagh Patrick, from where St. Patrick mythically drove the snakes out of Ireland (my husband’s bright idea), we worked with Google maps and around wandering herds of sheep to get a view of Lehanagh Pool, an open-water IMTA testing site (my brilliant idea). There, Irish scientists are trying to farm a whopping 10 sea species on a single site. As the sun shone orangey and dipped behind the hills of the Iorras Aithneach peninsula, the view of the IMTA site was backlit. It resembled a watery three-ringed circus with poles and nets that reached skyward like a trapeze apparatus.

The research site is one of several in Europe and South America that contribute to an aquaculture data collection and implementation effort called the Astral Project. Operated by scientists at the Irish Marine Institute, Lehanagh Pool sits a quarter mile from the rocky shore in Bertraghboy Bay. This protected area of the Irish coast has an aquacultural history that dates back to the 1950s and includes commercially farmed salmon and experimental farmed cod.

Marine Institute scientist Pauline O’Donohoe manages the non-commercial, experimental site, which holds the first multi-species license issued in Ireland. The scientists feed the Atlantic salmon and some lumpfish that swim in the pens; the latter are being tested to see if they can help control sea lice, a common problem at commercial salmon farms.

The extractive species at Lehanagh Pool, which filter out particulate waste from the water as food, are large great (or king) scallops, smaller variegated scallops, and native Ostrea edulis oysters. Minerals and carbon already dissolved into the water are extracted by several types of seaweed. If this were a commercial operation, all these species could be sold to consumers.

At the same time, benthic scavengers (or bottom feeders), in this case, sea cucumbers, remove particulates from the upper surface of the seafloor, such as uneaten food and waste from finfish. Again, were this a commercial IMTA, the sea cucumbers could be exported and sold to the Chinese market.

The only sea creature being raised at Lehanagh Pool that would not be raised to market size are the European lobsters. Their purpose within the system is to eat the finfish waste in the water column and to graze on the biofouling organisms that attach themselves to IMTA gear. But O’Donahoe said these lobsters could be released as juveniles to enhance stock.

Finally, spiny sea urchins are also farmed at the site, fed with the seaweed that is growing there, a process that again enhances the circularity of the project, O’Donahoe said, as the sea urchin flesh could be sold as uni.

Many environmentalists oppose salmon farms because the fish can escape from their pens and breed with wild populations. That concern is outside the scope of testing at this project, Astral Project lead scientist Elisa Ravagnan said.

For now, the Lehanagh Pool IMTA is still in the research phase. O’Donahoe and her team have so far spent three years collecting data about the growth of each species and the project’s environmental impacts. When enough data has been collected and analyzed, the scientists would next need to test whether the system can be implemented commercially, O’Donahoe said.

Back in Maine, scientist Nichole Price, who runs the Center for Seafood Solutions at Bigelow Laboratory for Ocean Sciences in Boothbay, said a growing body of evidence demonstrates that farmed seaweed is beneficial to the surrounding ocean. But Price was hesitant to predict just how much seaweed and how many filter feeders or benthic scavengers it would take to offset the waste stream of a salmon farm. It would need to be a significant amount, she said, which could make a commercial aquaculture operation less profitable.

In Maine, operators can get licenses to run an IMTA site as long as all of the species involved are approved during the lengthy licensing process. Bangs Island Mussels is one of a small handful of IMTA aquacultural operations in Maine waters. For over a decade, it has been raising both mussels and kelp in Casco Bay. For several years, it also had some scallops on lines.

“The beautiful thing about our form of IMTA is that our two species are regenerative. (Because we aren’t feeding) a species at the start of the system, the result is a net-net positive impact,” Bangs Island Mussels CEO Matt Moretti said.

The challenge of increasing the number of species that a single operation can farm is to do it in a way that takes into account the business’s limits of crew time, equipment, site space and water knowledge, Moretti said. For example, at Bang Island Mussels, the boat that harvests kelp in the spring is used the rest of the year for maintaining mussel rafts and changing nets.

Other than new species of seaweed, Moretti has no immediate plans to add species to the Bang Islands Mussels site. But, if he were, he thinks a benthic feeder would be particularly attractive.

“Regenerative IMTA allows us to maximize the good we do for the environment and maximize the nutritious food that we produce for our community,” Moretti said.

Irish Seafood Chowder

Irish and New England seafood chowders share a dairy base and the inclusion of potatoes. But the flavors differ, as do the fish and shellfish available on respective sides of the Atlantic Ocean. While New Englanders start with bacon or salt pork, the Irish generally get flavor from fresh smoked haddock (called finnan haddie), white wine, mustard and dill. This Irish seafood chowder recipe was adapted from one by Dublin chef Eric Matthews that was published in “The Irish Times.”

Serves 6 as a main course 

1 large potato, diced in ½-inch cubes
1 small, sweet potato, diced in ½-inch cubes
Kosher salt
4 tablespoons unsalted butter
4 shallots, peeled and sliced
1 large leek (white and light green parts only), sliced and washed
1/4 cup diced celery or fennel
2 garlic cloves, peeled and crushed
1 teaspoon dried kelp flakes
1 cup dry white wine (such as Sauvignon Blanc)
1 pound smoked haddock, cut into 1-inch pieces
2½ cups seafood stock
2 cups whole milk
1 cup heavy cream
¼ cup chopped fresh dill, more for garnish
2 tablespoons Dijon mustard
1/4 teaspoon white pepper
1-pound flaky white fish (such as cod, hake, halibut, pollock), cut into 1-inch pieces
1 pound mussels, beards removed and rinsed
1/2 pound fresh scallops, foot removed, and cut into quarters
Lemon wedges
Brown bread for serving

Place the white and sweet potatoes in a large, heavy-bottomed pot. Cover with cold water. Add 1 tablespoon salt. Place the pot over high heat, bring the water to a boil and cook until the potatoes are just tender, about 5 minutes. Drain the potatoes and set them aside.

Return the pot to the stove, this time over low heat. Add butter. When the butter has melted, add the shallots, leek, celery or fennel, garlic, kelp flakes, and 1/2 teaspoon salt. Stir well so that the vegetables are coated in the fat. Cook gently, stirring often, until the vegetables are translucent, 8-10 minutes.

Add the wine and increase the heat to medium-high so that the wine boils. Cook until the wine is reduced to about 1/4 cup, 4-5 minutes. Add half of the finnan haddie pieces, stir, and cook until the fish is opaque, about 4 minutes. Add the stock, milk, cream, dill, mustard and white pepper. Bring the mixture to a simmer and cook gently for 5 minutes. Transfer mixture to a blender (or use a stick blender) to puree the chowder base.

Return the base to the pot, add the remaining finnan haddie, flaky white fish, mussels, scallops, and reserved potatoes. Place the pot of chowder over low heat and cook until the fish is opaque, the mussels have opened, and the potatoes have warmed through, 5-6 minutes. Discard any mussels that have not opened. Taste the broth and adjust for salt.

Serve hot, garnished with fresh dill and lemon wedges, and alongside thick slices of brown bread.

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