Brook trout are spectacular fish, no matter where you find them. Long revered among fly fishermen, these colorful members of the char family serve as indicators of a healthy ecosystem, as they require cold, clean, well-oxygenated water in which to thrive.
Most people associate “brookies” with northern New England and Canada, but the fish also inhabit more southern parts of the region, including southeastern Massachusetts. In the coastal town of Wareham, a population of native brook trout have inhabited Red Brook—part of the Trustees of Reservation’s Lyman Reserve—since the glaciers retreated from New England some 12,000 years ago. The small brook—in many places just five feet wide—originates in Plymouth’s spring-fed White Pond and flows into Buttermilk Bay, on Wareham’s eastern border and adjacent to the Cape Cod Canal.
The fascinating thing about the trout that live in Red Brook is that many of them spend their winters in salt water before returning to fresh water for the late spring, summer, and fall. These so-called “salter” brook trout have adapted to tolerate both fresh and marine waters, and move freely between the two zones depending on the presence of predators, food, and water temperature.
Biologist Steve Hurley (now retired) of the Massachusetts Division of Fisheries & Wildlife (MassWildlife) studied the salters of Red Brook for many years. Each June, he and a team of volunteers monitored the trout population using a process that involves “electrofishing” with a large battery pack attached to a metal wand. The device issues bursts of electricity through the surrounding water, temporarily stunning the trout and other fish, which are then scooped up in nets as they float downstream and transferred to coolers. For such an apparently delicate creature, they recover remarkably quickly from this treatment.
Once ashore, the team records the length and weight of each fish then implants them with a tiny PIT tag. These tags allow researchers to monitor the seasonal movements of the trout as they swim past receivers placed along the waterway. In past years, some of the larger trout were implanted with acoustic tags that could be picked up by receivers placed in Buttermilk Bay and the channel leading to the Cape Cod Canal. Data showed that at least some of the larger Red Brook fish spent part of winter in this relatively deep, marine water.
How large do the Red Brook trout grow? Past electrofishing studies have yielded fish up to 15 inches long, although most fish in the brook measure less than six inches. Undoubtedly, bigger fish exist. Records taken from the early 1800’s show that salter brook trout caught in southeastern Massachusetts routinely attained weights of two pounds!
What do the trout in Red Brook eat? Pretty much anything they can fit in their mouths. Common prey items include small eels, mummichogs (killifish), grass shrimp, juvenile herring, earthworms, insects, and invertebrates.
Red Brook itself has seen so many manmade alterations and other human-induced environmental problems over the last two centuries that it’s a miracle a wild population of brook trout has managed to survive. In the 19th and 20th centuries, much of the brook’s upstream portion was rechanneled to accommodate this agriculture, destroying critical trout habitat such as undercut banks and deep pools. To make matters worse, the use of pesticides by the cranberry growers reduced the natural supply of insects the trout depend on for food, while excess nutrients emanating from septic systems and fertilizers can create algae blooms that rob the water of oxygen. Also, over the years, most of the large shade trees were removed from the brook’s banks, leaving the fish vulnerable to predation and causing water temperatures to rise beyond the trout’s comfort level. The introduction of invasive species such as large- and smallmouth bass, which prey on juvenile trout, further threatened the fishery. As biologist Steve Hurley has said, brook trout populations often face death by a thousand cuts.
Fortunately, groups such as Trout Unlimited, the Sea Run Brook Trout Coalition, and the Trustees of Reservations, in concert with state agencies, have stepped in to protect Red Brook’s trout by restoring and enhancing the waterway through a series of measures, most carried out by dedicated volunteers. These have included 1) removing concrete flumes that affect natural steam flow and inhibit fish migration; 2) rechanneling the river to create a more sinuous, natural flow that creates undercut banks and pools where the trout can hide and remain cool; 3) adding logs and other debris to create deep pockets and eddies that provide the trout with shelter and shade; 4) and planting shade trees along the banks to provide protection from predators and direct sunlight. Limiting fishing pressure was yet another boon for the trout. While recreational fishing is allowed in Red Brook, anglers may only use artificial lures, and all fish must be released.
Of course, Red Brook isn’t the only estuarine system in southeastern Massachusetts that supports wild brook trout. At least four Cape Cod rivers also host salters, including the Mashpee, the Quashnet, the Coonamessett, and the Childs.
Today, the brook trout found in all the above systems continue to be threatened by climate change, groundwater loss, excess notification, and habitat fragmentation. And the fight to protect them is ongoing and ever-changing. However, as the Red Brook population of salters shows, victories can be won through the hard work and combined efforts of many different groups and individuals who care about the environment and the animals that depend on clean, healthy ecosystems.
