1996 Fact Sheet: Restoring Herring Populations
Restoring Herring Populations on the Mattapoisett & Weweantic Rivers
BackgroundAnadromous fish species like alewives (Alosa pseudoharengus) and blueback herring (Alosa aestivalis) have declined dramatically during the past century in Buzzards Bay. Not only are these fish historically important as a fishery in Buzzards Bay, they are also an important food species for many fish, whales, and coastal birds such as the roseate tern (Sterna dougallii), a US endangered species whose largest colony in North America resides in Buzzards Bay.
Today, many of the herring runs in Buzzards Bay support only a fraction of their estimated maximum annual population. Reduced herring populations in any particular river or stream system can be caused by a number of factors including physical obstructions to migration, overfishing, poor water quality, or inadequate spawning habitat. Of these, physical constraints in the form of dams, roadway construction, and other water control structures are by far the greatest impediment to herring migration in Buzzards Bay rivers.
The Buzzards Bay NEP has invested considerable effort in helping to improve herring runs in the Bay's most productive river systems and continues to work closely with the Massachusetts Division of Marine Fisheries (DMF) to identify where anadromous fish improvements are needed and will provide the most benefit. Together the Project and DMF have identified two river systems in the Buzzards Bay watershed as priorities for herring restoration - the Mattapoisett and Weweantic.
The Mattapoisett RiverThe Mattapoisett River which begins at Snipatuit Pond in Rochester and flows 20 miles south to its discharge into Mattapoisett Harbor, has historically contained the Bay watershed's most productive and abundant herring populations. At its peak at the turn of the century, the river had an estimated annual sustainable yield of 3000 barrels, or approximately 1.4 million fish, with the total fish stock estimated at 1.8 and 1.9 million fish per year. During this century, the fish stock has drastically declined until the fishery was almost extinguished. Local efforts, starting in the mid 1980's, have allowed the herring fishery to begin a slow recovery and the total fish stocks for 1989, 1990, and 1991 were 43,000, 51,000, and 65,000 herring, respectively. Although the population is increasing, the total stock is still less than 3% of the former population.
In the summer of 1990, a one-mile long section of the river from the Snipatuit Road culvert to the mouth of Snipatuit Pond was dredged to allow easier fish passage. This project was jointly funded by the towns of Rochester, Marion, and Mattapoisett and Alewives Anonymous - a nonprofit group that has contributed greatly to the improvement of herring populations in the Buzzards Bay area. Also in the late 1980s DMF installed a fish ladder on the river leading into Snipatuit Pond. Despite these efforts, two major barriers on the river in the early 1990s were greatly inhibiting the ability of fish to reach their spawning grounds.
Near the river's headwater spawning area in Snipatuit Pond, five culverts beneath Snipatuit Pond Road were small in diameter (30") and submerged. Because herring typically migrate during daylight hours and lighted passages are required for migration, these long darkened culverts presented a significant obstacle to their upstream migration. The solution to the problem was the replacement of the small culverts with a single large box culvert, which would allow for more light to reach the interior of the culvert and eliminate the existing obstacle to migration. The Buzzards Bay NEP funded this project and construction was performed by the Rochester Highway Department.
Near the river's mouth at the Route 6 dam, additional problems were impeding fish passage on the Mattapoisett. The fishway at the dam restricted upstream passage of alewives as it was both too steep and too turbulent. In addition, water elevations at the dam which are controlled for municipal water supplies required better management during normal operating conditions and during herring run season (March through May). In order to accomplish these connected goals of improving the fish ladder and improving water management, the towns of Mattapoisett, Marion, Rochester, and Fairhaven joined together to seek funding for the project. Improvements to the dam structure was funded by the Commonwealth of Massachusetts with local support from each of the towns. Additional funds for the fishway were provided by the Buzzards Bay NEP. The new fish ladder is a Denil-type structure and was installed at the dam in December 1996.
The Weweantic RiverBeginning in the town of Wareham, the Weweantic River system is one of the Bay areas largest subwatersheds encompassing 55,438 acres in the towns of Wareham, Carver, Rochester, and Middleborough. Land use is dominated by cranberry production and the upper reaches of the Weweantic are intermingled with bog operations. The Weweantic River currently has no significant population of herring. The major spawning area on the river is Horseshoe Pond which is a relatively short distance from the farthest extent of tidal influence. The entrance into the Pond for migrating herring is obstructed by a dam which prevents the river system from sustaining its maximum herring population. According to estimates performed by the Massachusetts Division of Marine Fisheries, the river has an estimated possible annual production of approximately 100,000 fish per year.
In 1996, the Buzzards Bay NEP in cooperation with DMF and the Town of Wareham applied for and was awarded funding from the Massachusetts Department of Environmental Protection s.319 program to construct a Denil-type fish ladder in the Weweantic at Horseshoe Pond. The ladder was designed by fishway engineers at the US Fish and Wildlife Service to be installed in the dam structure and will remove the single most important impediment to fish migration in this system. As part of this project, DMF will stock Horseshoe Pond with 5000 herring to boost the population and an educational display will be created highlighting the herring restoration efforts in the Bay drainage area to be used on a rotating basis in town halls, libraries, and schools. Construction of this project will begin in the first part of 1997.
[See this additional information on the Historical Weweantic Run]