Weed Control Alternatives

Grass Carp notes – Carlson 8-2-16

**Sources: Nancy Mueller, NYSFOLA “Diet for a Small Lake”**

CONS:

Grass Carp eat all weeds and are more effective against pond weeds. Milfoil is NOT the favorite food of grass carp.

A major concern is stocking rate (DEP permit needed); success seems to depend heavily on stocking and re-stocking rate.  After carp have cleaned out weeds, they will eat anything, which can result in algae blooms.  Advice is to start slow.

Carp can grow very big (75 lbs) and result in propeller incidents, etc.

PROS:

Grass carp can work, but results vary greatly among lakes.

A possible lake to visit is Song Lake in Cortland, NY.  It is a little smaller than LL. They have targeted milfoil. They have worked to overcome an overstocking problem but they are apparently satisfied with the results.  Contact: Tarki Heath, 315-696-5262 (NYSFOLA board member).

 OTHER COMMENTS:

Lakes without forested watershed (e.g. Loon Lake) get so much runoff that some form of weed control is needed.  In NY, mechanical harvesting is the most popular method as results are more certain, and less likely to raise concerns about second-order effects associated with other methods, such as: aquatic herbicides, aquatic insects, and suction. (Some companies are now marketing aquatic herbicides, but the ingredients not always disclosed, and the DEC does not have regulations for them.)

It may be hard to get a permit for muck suctioning. If one is curious, one can look up “Muck B-Gone”.  The academic community is suspicious.

Benthic barriers (aka “weed mats”)have fewer possible side-effects but are hard to distribute lake-wide. Weed mats now require a DEC permit.

Lake Salubria (Bath, NY) Experience with grass carp

Per:  Niki Brown (607-776-3751) past president of Lake Salubria Association from

phone conversations on 8/27/15 (resides at 6839 Lake Salubria Drive)

Pertinent Points

  1. Prior to stocking grass carp Lake Salubria only had a weed harvester 2-3 times/year.
  2. Bath has planned sewers for the lake, but residents rejected.
  3. 100% agreement from property owners is required to introduce grass carp.
  4. Only triploid (sterile) grass carp can be stocked.
  5. Lake Salubria was approved by the DEC for 500 fish.
  6. Initial stocking was 200 at $20/fish in April of 2009.
  7. 50 more were stocked in May of 2011.
  8. Life expectancy is expected to be around 10 years.
  9. Stocking was very successful.  No weeds now appear on the surface.
  10. Experience indicates that they love Milfoil.  They eat from inside a weed stand outward.
  11. The major results were seen after about 3 years.
  12. Lake Salubria is a big bass fishing lake.  There were some fisherman complaints as bass need weeds.
  13. Grass carp eat less as they grow older.
  14. Residents believe that lake property values have been improved.