The Gulf of Maine includes vital, vulnerable pockets of diversity like the Cashes Ledge area. Photo: Brian Skerry
The ocean is where much of my curiosity stems from. Growing up on the coast of Maine, some of my fondest memories are of afternoons crouched over rocky tidepools watching periwinkle snails move with a slow precision. Or kayaking through the salt marsh looking down to see baby fish darting in and out of sight as a heron stands attentively on the banks nearby.
These lucky encounters shaped my understanding of how special and unique this marine environment is. These are also the moments that led me down a path of observing patterns, seeking explanations, and often leaving with more questions than answers. My early exposure to the ocean sparked an interest in understanding changes in the Gulf of Maine, and how these changes impact the people and marine communities that depend on this unique body of water. What I am seeing today worries me.
What is Happening Beneath the Surface?
The Gulf of Maine is one of the most productive ecosystems in the world, home to over 650 fish species, 270 marine plants, 1,400 invertebrates, and 32 species of marine mammals. Despite this immense variety, the rich biodiversity that exists there is in danger. Climate change and other human-induced changes are causing species abundance and make-up to shift in ways that could threaten the health of ecosystems and fisheries’ success. As environmental protections are being gutted by the federal government – including expanding offshore oil drilling and opening marine national monuments to commercial fishing – the health of our ocean is in a precarious position.
The Gulf of Maine is warming nearly three times faster than the global average. Below the surface, New England’s waters are teeming with marine organisms that are experiencing dramatic changes of all kinds. At the base of the food web, photosynthesis by phytoplankton – microscopic marine organisms – has declined by 65% since the early 2000s.
Tiny floating phytoplankton still rapidly grow and accumulate into “blooms” twice a year, but warming has shifted the timing of these events. Phytoplankton feeds zooplankton, slightly larger critters including copepods that serve as a critical energy source for all sorts of fish and marine mammals – from herring to North Atlantic right whales. When the timing of phytoplankton blooms shifts, it affects food availability across the food web. As a result, these changes in timing and productivity at the lowest levels of the food web have implications for the feeding and migration patterns of many marine species throughout the Gulf of Maine ecosystem.
Changes Further up the Food Web
Ecologically and commercially important species, such as lobster and northern shrimp, are in decline or are shifting northward. Meanwhile, species historically not found in the region, such as longfin squid and black sea bass, are detected increasingly often. As new species move into the region, delicate predator-prey interactions change.
For example, the makeup of prey fish in the region has shifted with warming oceans and increased fishing. Since the 1960s, Atlantic herring in the Gulf of Maine have declined, while butterfish have increased. These changes have consequences further up the food web. Atlantic puffins, for example, have historically relied on Atlantic herring to feed their chicks. As herring populations have declined, successfully re-established puffin colonies in the Gulf of Maine have needed to adapt to changing prey, which poses risks to the continued recovery of colonies in the region.
Changing ocean conditions have also affected kelp and eelgrass – species that provide important habitat to lobster, bivalves, and fish such as cunner and pollock. Between 2001 and 2018, average kelp cover declined by 10-30% in the Gulf of Maine region, varying by region. Surveys of eelgrass beds in Casco Bay showed that eelgrass had declined by over 54% between 2018 and 2022. Another survey conducted in midcoast Maine showed a 60% decline in eelgrass abundance between 2005 and 2024.
Why Marine Biodiversity Matters
Biodiversity and climate resiliency go hand in hand. Healthy, diverse ecosystems are more resilient to extreme conditions and changes in the climate, such as warming waters and shifts in ocean chemistry. They also play a critical role in absorbing excess carbon from the atmosphere, protecting coastlines from storms, and supporting commercially and culturally important fisheries. Monitoring and understanding the changes that are occurring in the Gulf of Maine is critical to crafting appropriate conservation responses.
That’s why CLF is working tirelessly to protect important habitat areas, such as Cashes Ledge, which is home to vibrant kelp forests and a diverse array of marine invertebrates and fish species. Protecting diverse and abundant marine communities is critical to building healthy and resilient ecosystems. These areas provide refuge for young fish, support stable food chains, and encourage genetic diversity in marine species – possibly including genetic variations that will be more resilient to changing oceanic conditions.
A Vibrant New England Depends on a Healthy Ocean
So much of what makes New England unique is tied to our ocean. From seafood served in coastal towns to reestablished puffin colonies in Muscongus Bay, many of the economies, identities, and traditions in the region rely on healthy, vibrant marine ecosystems.
The future of biodiversity in the Gulf of Maine will largely depend on what we do today to curb climate change and push forward conservation measures. The Trump administration is recklessly stripping and defunding climate solutions and environmental protections, even attempting to open up the Atlantic to oil and gas drilling. It’s more important than ever to track the changes that have already occurred, manage the shifts that are still to come, and advocate for meaningful, science-based management and conservation.
Ellie Batchelder is a University of Victoria graduate student working as a intern for the Ocean program this summer.
