Milfoil Eradication in Hosmer
Luc caught a big one - big milfoil that is!
Craftsbury's Milfoil Eradication Team has been on the water surveying since the end of April and scuba diving to hand pull this noxious aquatic weed since mid-May. (Water temperatures were as low as 50 degrees when we started diving. Brr!) But now the water temperature is a comfortable 76 degrees at the surface, and a manageable 60 degrees at the bottom.
We were lucky both of us have been diving right from the start in mid-May. This early start has really helped to get the jump on milfoil growth compared with last year’s relatively late start in June. We have harvested 52 cubic feet to date this year compared with 54 cubic feet at this time last year.
Even though the total amount of milfoil collected to date is nearly the same as last year, we feel that the residual amount of milfoil biomass remaining in the lake at this time is considerably less. This change may be a consequence of employing two divers and more hours under water than the last two years (112 hours to date in 2011, 102 hours to this date in 2010, and 37 hours to this date in 2009).
Another indicator of the amount of residual milfoil in the lake could be the cubic feet of milfoil we have been able to collect per hour of scuba time spent collecting. In 2009 we collected at the rate of 0.86 ft3 per hour, in 2010 we collected 0.52 ft3 per hour, and in 2011 we have only been able to collect at the rate of 0.46 ft3 per hour. This year's plan was to keep the milfoil population in the lake at as low a level as possible by hitting it hard and early so that it wouldn't get out of control and grow faster than we could find and pull it. These numbers seem to verify the merit of our strategy.
Most of the milfoil harvested this season, so far, has come from the North Bay, the small bays on both sides of the Lake and the relatively shallow central channel near Rob and Linda Libby's, and Hosmer Point's Bay. Only a few small handfuls have been found to date so far in the South East Bay and none in the South Bay near the Center.
One concern we have this year is the increasing amount of floating, detached milfoil stalks in the Central Channel. This appears to be a result of turbulence created by boat motors, as the problem doesn't seem to be as acute in the bays closed to motor boats. Fragmentation of milfoil plants in the presence of turbulence is one of this species’ most efficient reproductive strategies, so this can be a challenge.
Want to help in the effort to keep Big Hosmer open for all users? We welcome volunteers in our effort to control milfoil on the lake. Contact John Brodhead if you are interested.