Dive Deeper

Right whales are in Maine waters. Here are the facts, how we know them, and why they matter.

Most Maine lobstermen have never seen a right whale, and many don’t even know someone who has. So it’s understandable if you’re skeptical. But with Congressional funding, DMR and other groups are now monitoring right whales in state and federal waters off the Maine coast, providing new and reliable data on where and when they are present.

Maine DMR, NMFS, and other organizations monitor right whales using aerial surveys (planes), vessel surveys, and underwater microphones that detect whale calls. You can see this work through online mapping tools. 

Visual observations obtained through aerial and vessel surveys are generally conducted monthly to increase our understanding of where and when right whales frequent Maine waters. Maine DMR has been collecting this information since 2022 through the DMR right whale research program generating Gulf of Maine-specific data to inform future management discussions. Whalemap.org is a real-time mapping tool that shows where whales have been recently detected through aerial and vessel surveys, acoustic gliders, and chance sighting reports. 

Passive acoustic monitoring devices listen for whale calls around the clock to detect whales that may not be seen through visual surveys. This provides another layer of data to improve our understanding of how right whales use the Gulf of Maine. The Passive Acoustic Cetacean Map allows users to explore when and where right whales (and other large whales) have been detected using passive acoustic listening technologies. Unlike WhaleMap, these data are not available in real time because many recordings are only collected from these devices every 4-6 months.

Ocean conditions in the Gulf of Maine have varied significantly in recent decades, reaching record warm temperatures, and then shifting back to cooler waters. Changes in water temperature affect ocean currents which in turn impacts where whale food becomes concentrated. Right whales are kind of like us—they follow their stomachs. When food shifts, whales shift with it. That means the places and times when whales are seen may not match what fishermen remember from years past. This is why ongoing monitoring and new data are so important.

NMFS’s updates its North Atlantic right whale population estimate annually. The most recent estimate, released in late 2025, places the population at 384 whales and marks the fourth consecutive year of modest growth. Less than 300 right whales remained in the early 1990s, but the population gradually recovered to 480 whales by 2011. The population then declined for nearly a decade, due in large part because of changing oceanographic conditions which shifted prey and whale distribution, affecting feeding opportunities and moving whales into areas where protections were not yet in place. Since reaching a low point around 2020, the population has slowly increased, and births now exceed deaths. There is cautious optimism that the population decline has ended. However, the population remains small and federal laws require measures to aid the recovery of species.

The Marine Mammal Protection Act (MMPA) and the Endangered Species Act (ESA) require the federal government to reduce human-caused death and injury to right whales. 

NMFS does not base management decisions solely on documented entanglements. NMFS calculates the risk of harm from fisheries based on gear type, where gear is fished, and where whales are likely to be. That’s why collecting timely and accurate data is so important to inform the development of new management measures.

What we don’t know

  • Whale monitoring is essential, but it cannot tell us everything. Surveys cannot cover every area, every day and are limited by weather, daylight, sea conditions and whether whales are visible at the surface. Acoustic monitoring devices can detect whales only when they are calling within range.
  • Not all entanglements are observed. Even when an entangled whale is seen, gear markings may not be visible or recoverable, making it difficult to determine where the gear came from or identify the fishery involved. In some cases, the precise cause of death also cannot be determined. 
  • Although right whale data will continue to improve, uncertainty remains about where right whales occur and how their distribution is changing.
  • Scientific uncertainty cuts both ways. It’s a reason for caution, but it also underscores the importance of collecting and using Maine-specific data.
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