There is more to Mill Brook than meets the eye. Wild brook trout to be exact, and a number of other species that continue to spawn and live in the ribbon of water that courses through Chilmark and West Tisbury on its way to Tisbury Great Pond.
In September 2012, a team led by Steve Hurley, southeast district fisheries manager for the state Division of Fisheries and Wildlife, conducted a survey of Mill Brook at multiple locations to officially document the existence of wild brook trout. Team members were armed with small electronic devices in backpacks that were used to generate an electrical charge and temporarily stun fish.
On Sunday, March 23, Mr. Hurley will visit the Vineyard to talk about the fisheries of Mill Brook, past, present and future, the results of the September 2012 fisheries survey that documented wild brook trout in the system, and the results of 2013 water temperature monitoring conducted along the four mile length of Mill Brook, funded by the Sea Run Brook Trout Coalition with a grant from the Edey Foundation. The presentation begins at 3 pm in the West Tisbury Public Safety Building on State Road opposite Conroy Apothecary.
In an official “Fisheries sampling report on Mill Brook and tributaries – West Tisbury,” dated September 18, 2012, Mr. Hurley described what his team found.
“A total of eight fish species were sampled in Mill Brook and two small tributaries (Witch Brook and an un-named tributary to Priester’s Pond). Reproducing wild brook trout were found in the upper reaches of Mill Brook and in the Witch Brook tributary as well as in an un-named tributary to Priester’s Pond. A single adult (apparently wild) brook trout was captured below a small impoundment (Berresford’s Pond) on the river. No brook trout were found in the sampling area below Old Mill Pond and above the Town Cove section of Tisbury Great Pond.”
In addition, Mr. Hurley reported, “Large numbers of American eels were captured in the lowest site surveyed on the river below the first dam (Old Mill Pond) above the brackish Tisbury Great Pond. American eel, anadromous and marine species have ready access to the Tisbury Great Pond during periodic man-made and natural openings of the pond to the sea but the openings may not coincide with peak migration times for elvers. American eels were present at the majority of sites sampled but abundance appears to be reduced compared to a brook with unimpeded access to marine waters. Passage of eels and other fishes may be impeded by the numerous dams along the main stem of Mill Brook.”
Brook trout occupy less than half of their original range in Massachusetts, according to DFW. These results reflect the condition of brook trout across their entire eastern United States range, according to an assessment released by Trout Unlimited and a coalition of state and federal agencies. These beautiful fish historically thrived in rivers and streams stretching from Maine to Georgia. The presence of brook trout in a watershed is considered an indicator that water quality is excellent. Declining brook trout populations can provide an early warning that the health of an entire stream, lake, or river is at risk, according to fisheries managers.
In his report, Mr. Hurley noted the observations of Dr. Jerome V.C. Smith, a medical doctor and former mayor of Boston, who, referring in 1833 to the brook trout of Mill Brook, remarked:
“In no place, however, do we remember to have seen them in such abundance as in Dukes County, upon Martha’s Vineyard… It was here in the month of November last, and of course in their spawning time; while returning home from a ramble among the heaths and hills of Chilmark and Tisbury, that crossing the principal brook of the island, our attention was attracted towards the agitated state of the water, and never do we recollect so fully to have realized the expression of its being ‘alive with fish’ as on this occasion.”
Mr. Hurley noted the modern challenges, including climate change, that now face the descendents of those brook trout. “Wild brook trout populations are persisting in Mill Brook watershed where suitable cold water habitat exists but their access to tidal areas is blocked by the numerous dams and barriers which do not allow the anadromous life history variant known locally as ‘salters’ or in Smiths early 1800s as ‘sea trout.’ The small stream coldwater habitats of Mill Brook are a habitat at risk due to climate change.
“Mill Brook has been highly modified with the presence of numerous impoundments that warm the waters of the brook, trap sediment, increase habitat fragmentation and reduce fish passage.”
The brook that feeds Mill Pond, the man-made water body next to the current town police station, is at the heart of a town tussle. One group would like to see the dam maintained and the pond dredged to maintain its historic scenic appeal. Another would like to see the watershed area returned to its natural pre-pond state.
In his report, Mr. Hurley listed six recommendations. These included:
* Establish stream temperature logging stations at multiple sites in the Mill Brook Watershed to assess present status and long-term trends.
* Consideration should be given to removing unneeded dams or culverts and updating road culverts to Massachusetts Stream crossing standards in the Mill Brook system to increase river connectivity and fish passage and improve cold water stream habitats.
* An inventory of dams and culverts in the Mill Brook watershed should be made with ownership status, condition, fish passage, etc.
* Landowners should be encouraged to increase riparian buffer zones to improve shading and woody structure in Mill Brook and its tributaries.
* Fisheries surveys should be conducted on the upper reaches of Mill Brook to further document the existence of brook trout in this area.