This story was originally published by bioGraphic and appears here as part of the Climate Desk collaboration
The Gulf of Maine is home to one of the most valuable fisheries in the United States. Every year, American lobsters (Homarus americanus) from the gulf fuel a multibillion-dollar industry, buoying fishing communities across New England and across the border into Atlantic Canada. The Gulf of Maine is also heating up faster than almost any other marine environment on Earth.
In the gulf, rising water temperatures and shifting currents have already triggered shocking declines in other mainstay catches, such as northern shrimp, and put surprising new species in fish traps. Now, ongoing research led by Joshua Carloni, a marine biologist with the New Hampshire Fish and Game Department, shows a potentially dire situation brewing for the area’s most valuable species—the lobster.
Right now, lobsters seem to be thriving in the Gulf of Maine. The adult population is near its record high, and commercial landings have been largely growing for decades. But since 2012, scientists studying the crustaceans have struggled to answer a worrying question: Where are all the young lobsters?
In 2012, divers off the New Hampshire coast armed with underwater vacuums suctioned parts of the seafloor for an annual survey of juvenile lobsters. They scarcely found any—and almost every survey since has turned up similarly dismal results. “It kind of had everybody scratching their heads as to what was going on,” Carloni says.
Digging into the state’s 30-year record of lobster abundance across various life stages, Carloni and his colleagues found that the problem is stemming from a specific phase of lobster life. Like butterflies, lobsters go through metamorphosis. But unlike butterflies, lobsters metamorphose several times. One of the most important transformations is when developing larvae give up living as free-floating plankton and settle on the seafloor to grow into adults.
Based on New Hampshire’s lobster population surveys, Carloni and his colleagues knew there were lots of adult lobsters in the Gulf of Maine, and those adult lobsters were birthing lots of planktonic larvae. But the larvae haven’t been settling—they aren’t growing into adults.
Now, in a series of scientific papers published over the past several years, Carloni and his colleagues explain what’s hollowing out the American lobster population.
The scientists looked at everything they could. Despite the Gulf of Maine’s prevalent warming, rising temperatures couldn’t directly explain the lack of juvenile lobsters. Neither could recent changes in the wind or the currents. Nothing seemed to be eating the larval lobsters in huge numbers, either.
But when Carloni and his colleagues looked at the relationship between juvenile lobsters and a certain single-celled zooplankton—a sesame seed-sized copepod known as Calanus finmarchicus—they had their answer loud and clear.
Rich in protein and fat, C. finmarchicus is a superfood for larval lobsters. Historically, lobster hatching season in the Gulf of Maine started around June and peaked in July. C. finmarchicus goes through its own seasonal cycle, too, with a new crop emerging every April and generally disappearing by early autumn. The overlap means the highly nutritious copepods have been in the right place at the right time to fuel the little lobsters’ transformation from plankton to bottom dwellers.
But in recent years, Carloni and his colleagues say, warming temperatures have been making American lobsters hatch earlier in the year. C. finmarchicus’s seasonal cycle has been thrown off, too: They’re spawning at the same time they used to but are vanishing sooner. “The entire season of Calanus has been truncated,” Carloni says. “They’re coming out and then disappearing early.”
Combined with an ongoing decline in C. finmarchicus abundance, which has dropped by about 70 percent during the lobster larval season since the late 1990s, the result of this mismatch is that by the time larval lobsters are ready to feast, the copepods are already gone. The seasonal cycle powering the Gulf of Maine’s lobster population has slipped out of sync.
For an ecosystem to function, certain things need to line up. Flowers must be open when bees are active; phytoplankton must bloom when migrating seabirds are at their hungriest. If not, serious consequences can follow.
The idea that mismatches in timing between predator and prey might explain the shifting abundance of some species was first proposed by fisheries scientists in the 1960s. More recently, concerns about climate change have given the match/mismatch hypothesis—as this mechanism is now known—more weight.
Sam Wilson, an ecologist at Simon Fraser University in British Columbia, says that as the timing of seasons shift, lobsters and zooplankton aren’t the only species experiencing a disconnect in their life cycles. Scientists have used the match/mismatch hypothesis to explain changes in everything from the chick rearing of seabirds in the North Sea to the reproductive success of solitary bees.
In her own work, Wilson is studying how changing environmental conditions are affecting when juvenile salmon begin their perilous migration out to the Pacific Ocean, and what kinds of consequences the new timing might have. As with the Gulf of Maine’s lobsters, Wilson says it’s not guaranteed the salmon will find their prey.
The changes hitting C. finmarchicus in the Gulf of Maine, specifically, might also explain other recent observations. In a paper published last year, for instance, U.S.-based scientists linked declines in the copepod’s population to changes in the feeding patterns and habits of the highly endangered North Atlantic right whale (Eubalaena glacialis).
Heather Kharouba, a biologist at the University of Ottawa in Ontario, has been studying the match/mismatch hypothesis for a decade. She says that while a wave of early studies sparked alarm within the scientific community that climate change would throw ecosystems into temporal chaos, more recent analyses suggest there is not enough evidence to believe things are going to get completely out of whack. Still, she adds, “there are systems where there is reason to be concerned.”
And one of those systems appears to be that of juvenile lobsters in the Gulf of Maine.
When Joshua Carloni and his colleagues first stumbled on the idea that mismatched seasonal cycles could explain the curious absence of juvenile lobsters in their seafloor surveys, they had based their analysis on data collected exclusively along the New Hampshire coast. Since then, follow-up work has shown that the relationship holds across the broader Gulf of Maine. “Everything seems to be pointing in the same direction,” Carloni says. C. finmarchicus “is driving this.”
What all of this means for the American lobster, the communities that depend on it, and one of the most valuable fisheries in North America is harder to say. But something does seem off.
In 2021, Carloni says, the population of older juvenile lobsters—let’s call them tweens—began to decline. By 2023, the number of tweens had dropped by 39 percent; fishermen were starting to notice. In 2024, declining lobster landings prompted the Atlantic States Marine Fisheries Commission to seek additional protection for the American lobster population by allowing fishermen to keep only large lobsters. (This month, regulators opted to abandon the rule after months of protest from fishermen, who said it was unnecessary and potentially ruinous for the industry.)
And while the number of adult lobsters in the Gulf of Maine has dropped slightly from its peak in 2018, the population is still near its record high, Carloni says. “It’s not panic time.”
American lobsters can live to the ripe old age of 100 years or more. They reach sexual maturity at 10 years old, and each spring a large female can bring 100,000 little larvae into the warming North Atlantic. There’s still time for things to turn around.
But in a changing climate, few things are as reliable as unpredictability. Ocean temperatures are rising in baffling ways, sea ice is becoming less consistent—and in the Gulf of Maine, the pieces of the ecological puzzle are not fitting together as they once did.
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