Herring Commission co-hosts conference on Aquatic Invasive Plants 3-23-18
Herring Commission co-hosts conference on Aquatic Invasive Plants
SouthCoast Today
Posted Mar 23, 2018 at 4:23 PM
Updated Mar 23, 2018 at 4:23 PM
LAKEVILLE — On March 7, the Middleborough-Lakeville Herring Fishery Commission and the River Herring Network, spearheaded by Abigail Archer of Woods Hole Sea Grant, jointly hosted a workshop on invasive aquatic plants at the Lakeville Public Library, according to Commission spokesperson Warden David Cavanaugh.
An enthusiastic group of concerned scientists, environmental agency representatives, volunteer advocates, local officials and fish wardens from around the state heard presentations about the statewide spread of invasive aquatic plants, control methods and permit requirements on the federal and state level, meant to ensure eradication methods will not cause other environmental damage.
Middleborough and Lakeville were represented by Lakeville Selectman John Powderly, members of the Lakeville Conservation Commission and Open Space committee, Middleborough Selectman Allin Frawley and Capital Planning Committee member Neil Rosenthal, and members of the Middleborough-Lakeville Herring Fishery Commission. Katherine Desrosiers represented State Representative Keiko Orrall's office.
According to local fish wardens and outdoor enthusiasts, evidence of a growing patch of an aquatic invasive plant called milfoil was especially apparent last summer on the Nemasket River, after appearing in the area several years earlier. The plants exist from below the Assawompsett dam to Bridge Street and are especially thick below the Vaughn Street bridge. Discussion at the workshop increasingly focused on how best to address the issue of invasive plants.
Invasive aquatic plants and animals are not a new problem, but a rapidly growing one according to experts, likely fueled by inadvertent introduction by human activity according to workshop participant David Wong of the Massachusetts Department of Environmental Protection. Climate changes, especially droughts and run off of nutrients from fertilizers and septic systems, as well as sediment from culverts and flooded areas, contribute to the problem. Cavanaugh explains that invasive plants are of concern to the Herring Fishery Commission because of potential blockage to the passage of newly hatched River Herring swimming downstream to the ocean and decaying plants removing oxygen from the water. The Commission worried that a fish kill of young herring observed last summer might have been caused by blockage or oxygen depletion.
Among the highlights of the workshop, Dr. Donald Padgett from Bridgewater State University reviewed what is known about invasive plants including fanwort, water chestnut and milfoil, the latter the primary problem in the Nemasket, where its entangling branches and stems create dense mats in the river. He also described a new invasive, the small Asian Clam, seen in the Assawompset Pond Complex and the river. These clams may alter water chemistry in a way that could negatively affect herring. Brad Chase and John Sheppard of the Massachusetts Division of Marine Fisheries, who study many aspects of river herring biology and population dynamics, cautioned that methods to eradicate invasive plants need to consider the movement of herring during the spawning season, which can extend further into the year than once believed, according to recent studies. Keith Gazaille of Solitude Lake Management, an engineering firm that contracts, among other projects, to control invasive plants, reviewed accepted control methods, including mechanical raking, biological controls such as certain weevils, and herbicides which he noted are now specific to particular plants and can be used in lower doses than previously; although a concern is that herbicides may negatively affect other species.
The workshop also explored methods to prevent the growth of unwanted vegetation including the longer range problem of sediment accumulation, which has been a concern of the Herring Fishery Commission for years, according to Cavanaugh. Michelle Craddock of the Massachusetts Division of Ecological Restoration talked about streamflow dynamics, which can affect both sedimentation and invasive plants, and which suggest that evening out streamflow where possible is a good strategy to avoid seeding in invasives on drier bottom in droughts, and helping to maintain passage of herring. Laeldon Langley of the Department of Environmental Protection reviewed permitting considerations of various control methods, a significant concern to both towns, Mr. Langley to acknowledge these processes to be comprehensive and layered, should the Army Corps of Engineers be involved, as well as the DEP. The workshop was recorded by Lake CAM and will air in both Middleborough and Lakeville, if feasible, given the length of the program.
