David Horner lives for lobster.

For half a century, day after day, he has taken his boat and headed into the cold waters of the North Atlantic off the coast of the US state of Maine, hauling the crustaceans from the ocean and bringing them ashore. From there, they are loaded onto trucks, sent to processing facilities and shipped to restaurants around the world.

Horner has voted for United States President Donald Trump three times and stands by his vote. He supports the president’s rollback of environmental regulations affecting commercial fishing operations like his own.

While he supports Trump on one policy, however, he’s disappointed in another – the president’s antagonistic approach to Canada, which borders Maine and is deeply entwined with the state’s lobster industry.

“I never heard anything about all this Canadian animosity in the campaign. I don’t know where that came from,” Horner told Al Jazeera. “As far as taking on Canada in this huge hostile trade war, I’m totally against it.”

Horner has watched the price of bait climb along with the cost of the diesel needed to power his boat.

Far beyond Maine’s rocky coastline, tensions involving the US, Iran, Russia and Ukraine have helped drive up global diesel prices, which hit record highs in September. Before the US and Israel began their war on Iran, diesel averaged $3.08 per gallon (3.8 litres) and has now more than doubled to $6.29.

Horner’s business is just one small fish in a very big pond. Maine’s lobster fisheries brought in $461m in 2025, underpinning a seafood economy that is dependent on the crustacean.

But that industry was put on edge when Trump announced sweeping tariffs on Canadian goods, prompting retaliation from Ottawa.

In August, Trump imposed tariffs on $20bn worth of Canadian goods while alleging unfair treatment of US products. Canada responded with retaliatory tariffs, but lifted the levies on seafood later that month.

Maine’s peak lobster season runs from late summer into early autumn, when catches surge and local processors can struggle to keep up. To handle the volume, much of the catch is sent to Canada for processing into lobster tails, meat and bisque before some of it returns to the US for sale. An estimated 60 percent of Maine’s lobster catch is processed in Canada.

“As soon as those tariffs went out, the screaming, literally and figuratively, in Maine and Canada was quite loud,” Justin Snyder, who works in the Maine lobster industry and is also a Democratic strategist, told Al Jazeera.

While seafood was ultimately exempted from the US-Canadian trade war, the tariff threat raised fears in the industry and put pressure on Susan Collins, the Republican senator who is in a close midterm election race with Democrat Troy Jackson.

A political divide

The race for the US Senate seat is tight. Jackson, the former president of the Maine State Senate, holds a very slight advantage.

A recent CNN poll suggested Jackson was leading by four percentage points, and a Marist poll indicated he was leading by two points, which is within the margin of error.

Collins has built a reputation in the Senate for voicing concerns about Trump’s policies and rhetoric but supporting his agenda when it comes time to vote. Collins has voted in line with Trump’s position on 92 percent of Senate votes during his second term, which began in January 2025.

However, Collins has broken with Trump on tariffs on several occasions. In April 2025, she voted to overturn tariffs on Canadian goods. Later that month, she supported a resolution to end Trump’s sweeping global tariffs, and in August, she pushed back against the White House over tariffs affecting seafood.

Beyond tariffs on Canadian goods and other imports, levies on foreign steel and aluminium have added costs for Maine’s lobster industry, which relies on the metals to manufacture the traps used by fishermen.

Jackson has been an outspoken critic of Trump’s tariffs, arguing that Collins has not done enough to challenge the president’s trade measures.

During their most recent debate, Collins touted her efforts to secure tariff exemptions for products such as road salt. Jackson pushed back, saying, “We can’t eat road salt.”

Trump removed 50 percent tariffs on some Canadian goods, including certain machinery and packaging products, on October 30, ahead of Tuesday’s midterm elections. At the same time, his administration extended the tariffs to other Canadian goods, including certain waste products.

“The Canada tariffs are just the dumbest thing in the world. I don’t think there’s anybody up here, Republican or Democrat, who can imagine why we’re involved in this thing,” Maine Republican strategist Lance Dutson told Al Jazeera.

“I don’t think that’s something people are going to point to Susan Collins on, though. I think she’s made it pretty obvious that she’s worked to try to mitigate those things.”

Treacherous trade relationships

Beyond the immediate costs to Maine businesses, the tariffs risk undermining the competitiveness of US exporters over the longer term.

Trade tensions between Canada and the US have led to Ottawa deepening ties with other countries like China, a move that potentially puts US exporters at a disadvantage.

“Our competitors, namely Canada, are now trading for the most part with those countries tariff-free or with very low tariffs. If we can’t compete with that, we have fewer markets to sell to, which puts downward pressure on the prices paid to fishermen,” Snyder, the Democratic strategist, said.

In China, one of the globe’s biggest markets for lobster, Canadian lobsters face a 7 percent tariff, a significantly lower burden than the 17 percent levied on Maine lobsters.

“They have friendlier trade relations with some of these countries as the US has become antagonistic toward some of its trade partners, giving them a competitive advantage,” Snyder added.

Climate change is also putting pressure on the industry because lobsters thrive in colder waters and are migratory.

Maine remains a major lobster-producing region, but warming waters could keep them moving farther north, making Canadian waters more abundant in the years to come and putting pressure on Maine’s industry.

Jackson has alleged Collins has not done enough to address the underlying causes of heightened prices for Mainers in the lobster industry and beyond, including tariffs.

“Troy spent most of his life working along the Canadian border, so he knows how important this relationship is to Maine’s economy, and he sees Trump’s tariffs for what they are: a tax on Maine families and small businesses,” a spokesperson for Jackson said in a statement provided to Al Jazeera.

The Collins campaign did not respond to Al Jazeera’s request for comment.

On the lobster boat, rising costs have made it harder to know whether a day at sea will pay off for Horner.

He plans to vote for Collins, but his support for Trump has grown increasingly complicated. That’s because of high fuel costs and tariffs affecting the cost of goods he uses regularly, leaving his interests at odds with a president who, in other ways, he has seen largely as an ally.

“I wish I could forget about everything else. I would be OK with him,” Horner said. “The high diesel fuel is the biggest enemy of the fishing industry.”