On Fri, 9 Aug 1996, Martin Muller wrote:

> Kelly, why the emphasis on removing or avoiding carp? Are they competitors for
> food with duckling broods? Do they eat ducklings?

Carp root around in the substrate, eating the various foods that Martin
mentions. They relish Elodea (duckweed) and will eliminate this aquatic
plant fairly quickly. Their activities eliminate much of the aquatic
vegetation and cause high turbidity. Numbers of aquatic invertebrates plunge
to very low levels in ponds with carp. Most ducklings are unable to find
enough food (both vegetation and animal foods) to survive in ponds with carp.

It appears that a similar relationship may exist between carp and northern
leopard frogs. The north Potholes/upper Crab Creek vicinity is the only
place in Washington where northern leopard frogs are known to remain despite
a fairly extensive eastern Washington distribution in the past. Char Corkran
has observed breeding congregations of adults in aquatic vegetation-rich ponds
during early March. Upon her return in April, the water level had risen,
allowing carp to invade. Aquatic vegetation was reduced, most surfaces of
sticks and stalks were covered with carp spawn and there was no sign of
leopard frogs, leopard frog eggs, or leopard frog tadpoles.

Rotenone kills many forms of aquatic life in the ponds, but much of this life
returns fairly rapidly. So, if we can make sure that carp are not among the
fauna that rebound, we can derive long-term benefits to certain native species.

Kelly McAllister
Washington Department of Fish and Wildlife
Wildlife Diversity Division