Environmental Challenges

While currently abundant in the Gulf of Maine, the American lobster faces an uncertain future due to rapidly changing ocean conditions. The collapse of the Southern New England fishery serves as a warning of what warming can do to even a well-managed stock.

Warming Waters

The Gulf of Maine has been warming faster than 99% of the global ocean, according to research published in Science. Sea surface temperatures in the Gulf have risen at approximately 0.03°C per year since 2004, a rate roughly seven times the global ocean average. This warming is driven by shifts in the Gulf Stream and the Atlantic Multidecadal Oscillation.

• Metabolic Stress: Lobsters function optimally in waters between 12–18°C. Above 20°C (68°F), their metabolism accelerates, increasing oxygen demand at precisely the time warmer water holds less dissolved oxygen.
• Range Shift: Southern New England landings collapsed from 21.8 million pounds in 1997 to just 1.7 million pounds in 2023—a 92% decline (ASMFC 2025 Benchmark Assessment). Meanwhile, the population shifted north: Maine landings surged to a peak of 132 million pounds in 2016. This northward migration continues toward Canadian waters.
• Reproductive Disruption: Warmer water alters the timing of egg hatching and larval settlement. If larvae emerge before their planktonic food sources peak, survival drops significantly.

Epizootic Shell Disease

Epizootic Shell Disease (ESD) is a bacterial infection that erodes the chitin structure of the lobster's carapace, creating pitted lesions that can penetrate the shell completely. The disease is caused by chitinolytic bacteria, with Aquimarina species identified as key pathogens.

• Temperature Link: Shell disease prevalence is strongly correlated with water temperatures above 20°C. In Long Island Sound, disease rates reached 30% or more in some survey years.
• Sex Bias: Female lobsters are disproportionately affected because they molt less frequently while carrying eggs (up to 2 years between molts), giving bacteria more time to colonize the shell.
• Economic Impact: Severely diseased lobsters are unmarketable. Biologically, infected females may produce fewer eggs or die before reproducing, reducing future stock recruitment.

Ocean Acidification

The ocean has absorbed roughly 30% of human-produced CO₂ since the Industrial Revolution, lowering surface pH by approximately 0.1 units (a 26% increase in acidity). The Gulf of Maine is particularly vulnerable because cold water absorbs more CO₂ and because freshwater runoff from rivers further reduces alkalinity.

• Shell Formation: Lower pH reduces the availability of carbonate ions that lobsters need to build calcium-carbonate shells. Larval and juvenile lobsters are most vulnerable during their rapid growth phases.
• Sensory Impacts: Research suggests that altered ocean pH may diminish lobsters' chemosensory ability—their capacity to detect food, mates, and predators through dissolved chemical signals.
• Food Web Effects: Acidification also harms the calcifying organisms lobsters eat, including sea urchins, mussels, and small gastropods, potentially reducing food availability.

Right Whale Entanglement

The North Atlantic right whale (Eubalaena glacialis) is critically endangered, with an estimated population of fewer than 360 individuals. Vertical buoy lines used in lobster and crab trap fisheries pose an entanglement risk. While right whale deaths from lobster gear are exceedingly rare relative to the scale of the fishery, a single mortality can have outsized effects on such a small population.

This issue led Monterey Bay Aquarium's Seafood Watch to place American lobster on its “Avoid” list in 2022 and prompted the suspension of the fishery's Marine Stewardship Council (MSC) certification. Federal regulations now require weak links, seasonal closures, and gear modifications, with ongoing research into ropeless fishing technology.