Trout in Mill Brook an Indicator of a Struggling Ecosystem
The Mill Brook in West Tisbury on Martha's Vineyard used to run "thick with fish," but that's no longer the case. As its waters warm from pollution and climate change, the trout, which require cool water temperatures, are becoming less and less numerous. Environmentalists say the trout are indicator of a challenged ecosystem.
One of the first signs of spring at the Mill Pond is the appearance of what West Tisbury residents call the "trout truck." It’s a truck driven by employees of the Massachusetts Division of Marine Fisheries that travels from Sandwich to Martha's Vineyard to stock this pond with hundreds of brook trout, a colorful fish about a foot long, with an iridescent head and a red belly. These hatchery trout are released in the pond every year primarily for fishermen to catch.
But once upon a time, the fish didn’t need to be trucked in to Mill Pond. Brook trout used to be a common species here, but Steve Hurley, the Southeast District Manager for the Massachusetts Division of Fisheries and Wildlife, said that over the years, the warming water temperatures have caused many of the native trout to die off.
"The trouble that’s happened is that river’s been dammed. They created these small mill ponds and that warms the water up. And basically the temperatures became too warm for the trout," Hurley said.
However, one of the biggest issues to removing the dam at Mill Pond is that it's historic, and is a symbol of the town of West Tisbury. The dam is a relic of the town’s roots as a place for grinding grain, as the water flowing over it used to power a mill. Today, the pond provides a scenic backdrop as people drive along West Tisbury Road. There are picnic tables off to the side, and mute swans paddle along the edges.
Conservationist and West Tisbury resident Prudy Burt described the scene. "We are standing at the sluice way of the Mill Pond dam in West Tisbury on the mill brook," she said. "The Edgartown West Tisbury road is right behind us."
Burt said that because the pond is barricaded by the dam, water temperatures can reach upwards of 90 degrees in the summer. But it wasn’t always like this.
"There are historical references to Mill Brook by a man named Jerome Smith, who was here in 1833. What he describes is a Mill Brook that was so full of fish, that he used the phrase, 'Never in our lives had we seen the term the waters being alive with fish as evidenced in what we saw at Mill Brook,'" Burt said.
"That’s not the case now. Historically there were herring present in the system, American eel, white perch."
She pointed out that all those fish are becoming increasingly rare to find in the pond. She said she'd like for the system to be a place where the waters were once again teeming with fish, but the dam keeps many spawning fish out, and it also keeps water flow to a minimum, which in turn allows it to heat up more quickly.
One of the main barriers to removing the dam at Mill Pond has been a question of aesthetics. Sean Conley of the West Tisbury historic preservation district said the pond is iconic to the town.
"It's sort of considered the jewel of West Tisbury, and it’s one of the few ponds that’s actually visible from the road, from a public area," Conley said.
If the dam were removed, the pond would drain into a thin stream and its edges would become more overgrown.
"We’ll end up with a skinny little brook and not the magnificent pond we have now," Conley said. "You’d end up with a brook that’s overgrown like the Mill Brook is just above it, barely visible from the road, and not really enjoyable."
Prudy Burt said she understood the concerns of people who want to preserve the aesthetics, but she said that the entire scene as it is is artificial. She also added that accepting the pond’s return to its more natural state as a stream doesn’t automatically mean it has to be unsightly.
"Instead of two-and-a-half acre Mill Pond, we have two-and-a-half acre Mill Brook Park, with a stream flowing freely through it," Burt said. "We could have a quiet space for bikers to sit on benches by the brook and watch our fish. It could look like anything we the town want it to."
In the past few weeks, West Tisbury's town meeting has voted to invest $40,000 into implementing what they say are changes to better the environment at Mill Pond. The town is still working to figure out what steps will be taken first.