Winter on Casco Bay

“Quiet and Clear” on the Bay

“Where hillside oaks and beeches  Overlook the long, blue reaches,  Silver coves, and pebbled beaches  And green isles of Casco Bay.“  -John Greenleaf Whittier

“Where hillside oaks and beeches Overlook the long, blue reaches, Silver coves, and pebbled beaches And green isles of Casco Bay.“ -John Greenleaf Whittier

For weeks each fall, a whoosh like the sound of a hot air balloon rising filled the air, as workers at the marina next to Friends of Casco Bay’s office shrink-wrapped boat after boat for winter storage. Now, it is quiet along the waterfront around us. Except for a few hearty live-aboards and tanker tenders, ours is almost the only boat left in the water at Breakwater Marina.


This is the season our scientists relish. Every month of the year, Citizen Stewards Coordinator Peter Milholland and Research Associate Mike Doan sample at ten inshore and offshore stations, adding to an invaluable catalog of long-term water quality data. By January, Mike and Peter usually have to shovel snow off Baykeeper and break ice around the hull to get it out of the slip. Sometimes, like easing out a car stuck in mud, they have to rev the engine and rock the boat back and forth to break a path to open water.


“Quiet” and “clear” are the words our scientists use to describe winter on Casco Bay. The bell buoys are muted under a coating of ice. On many mornings, the air is colder than the ocean, creating a bank of sea smoke that wraps around lighthouses and islands, making them appear to float above the water. The only other vessels they encounter are commuter ferries, scallop draggers, Coast Guard buoy tenders, and oil tankers steaming into Portland, their bows caked with frozen sea spray.


Taking Extra Precautions on Winter Sampling Trips

Preparing for Profile“Winter procedures” for our monthly staff sampling trips begin in November and continue until April. Bundled up in worksuits lined with floatation gear, Peter and Mike head out early in the morning in order to complete their 75-mile circuit of the Bay before dark. They must call to check in with the office every hour; our radios are communally tuned to VHF 16. The office staff stays alert for a squawk from the radio that may signal an emergency out on the water. Our 26-foot Seaway has even been reinforced with extra layers of fiberglass around the bow and stern to withstand winter conditions.

At each station, the researchers sample for temperature, salinity, pH, dissolved oxygen, water clarity, chlorophyll, and nutrients. “It’s important to sample all year long,” explains Peter, “in order to understand the overall health of Casco Bay. Dissolved oxygen is a key indicator of environmental health. Oxygen levels are usually higher in the winter because cold water holds more dissolved gases than warm water. Water clarity is better, since there is so little phytoplankton production going on.” The temperature of the water ranges from about -2oC (28oF) (below the freezing temperature of fresh water) to +2oC (36oF). It isn’t until March that the water starts to warm up to 3o.

One of their first stops is Halfway Rock, located midway between Cape Elizabeth and Cape Small. Here in the depths of winter, when phytoplankton growth slows dramatically, they have been able to keep sight of the eight-inch secchi disk as it descends to a depth of nearly 15 meters (50 feet).


As the profile trip continues to our sites in eastern Casco Bay, the boat often has to break through ice, leaving a trail of broken ice in its wake. Peter likes to hear the tinkling sound that the ice shards make as they skitter across the crust of frozen Bay. When the ice is an inch or more thick, the boat’s wake sets up an undulating wave that reverberates across the unbroken ice.


Mike says that when all of Brunswick’s Middle Bay is frozen over in February, it brings to mind Ernest Shackleton and his Endurance locked in the pack ice in Antarctica. Closer to home in Casco Bay, local historians talk of the winter of 1917-1918, when soldiers stationed on the harbor islands could walk to the mainland across the frozen water.


The boat stops at each station for 20 minutes at a time. Hands and noses become numb before the scientists are done sampling. Casco Baykeeper Joe Payne recalls that when he’s out on the Bay sampling in winter, chances are a fisherman will approach the boat to make sure that it’s not dead in the water. Joe savors that special camaraderie among those who venture out on the Bay in winter.


Seals and Seabirds Aren’t Afraid of a Little Ice

IceAlthough there are few other humans around, there seem to be more harbor seals than ever. In Broad Sound, the scientists have seen dozens of seals, each one claiming its own individual ice floe. Joe has watched an eagle perched on a cake of ice as it fed on a fish pinned beneath its talons. Mike especially likes seeing ctenophores, or comb jellies, as their soft, gelatinous bodies pulse through the surface waters.


By the time the Baykeeper heads back toward port, the lights are already on in homes on Peaks Island. As the crew turns into the marina, the last rays of the setting sun momentarily blind them, a final reminder that nothing is easy on the water in winter. They arrive back in the office tired and chilled. They’re usually asleep by 8 p.m. on profile days. Yet, these stewards of the Bay maintain that it’s a privilege and a bonus to be able to experience this “magical and dramatic” time of year on Casco Bay.


Winter Birds of Casco Bay

by Jane Arbuckle, former Friends of Casco Bay board member

While many of Casco Bay’s nesting seabirds and ducks migrate south to warmer climes and more desirable food supplies as winter approaches, there are large numbers of birds that either stay year-round or migrate to the Bay for the winter. The promise of open water and available food draw them to this coastal haven.


Common EiderThe Common Eider (Somateria mollissima) is one of the birds most commonly seen here. Many eiders nest on the islands of Casco Bay, although most of the population nests further north. Large rafts of them can be seen in the winter, feeding largely on mussels. Eiders are large ducks, with females ranging in color from a rusty brown to brown to gray. The mature males are a distinctive black and white.


OldsquawThe Oldsquaw (Clangula hyemalis) is an active, noisy winter visitor. The male has a characteristically long tail and winter plumage that is largely white, with a dark breast and back. The female appears whiter than the male. They nest principally in northern Canada and Greenland.



BuffleheadThe Bufflehead (Bucephala albeola) is a small duck, just over half the size of an eider. The head is distinctively large and puffy, with a steep forehead and short bill. The male has a white breast, black back and head with a white patch on the head. The female bufflehead is browner, with an elongated white patch on either side of the head. These winter residents nest inland near fresh water.


Illustrations by Rosita Moore