Sunday, July 1, 2007

Carp: Lake's friend, weed's enemy

(First appeared in OrlandoSentinel July 1, 2007)

I was dubious. I doubted they could do it. Fortunately, I was proven wrong.

In the past five years, my husband and I watched our pristine lake become more and more clogged with floating vegetation. In 2005, anxious for answers, I contacted the Florida Fish and Wildlife Conservation Commission, which sent out a biologist to survey the situation. Travis Connaway, a biological specialist who knew his stuff, arrived a few weeks later. Within minutes, Connaway made his assessment. Large stands of bladderwort had enveloped the lake.

Bladderwort is an invasive, free-floating plant common in many of Florida's lakes and waterways. Not one of the more noxious weeds such as the dreaded hydrilla, it can nonetheless cause problems. Because it grows so prolifically, bladderwort can render a lake unsuitable for swimming or boating. That's how bad it had become in our lake. We couldn't enjoy a relaxing dip without becoming entangled in itchy strands of weedy growth. Yuck!

To solve the problem, Connaway offered us three options. Method No. 1 was to hire a company to come out with a mechanical device to rid the lake of weeds.

This would be expensive, and Ralph and I had our doubts as to how successful it would be. We had already tried pulling out floating clumps of weeds by the armful each time we went for a swim. Occasionally we extracted massive piles of soggy weeds from the lake, piling them on our boat before transferring them to shore. If anything, that process seemed to increase the weed population, because bits and pieces inevitably broke off, floating away to start new plants. Hardly the win-win solution we were after.

Method No. 2 involved herbicides -- dousing the lake with chemical compounds supposedly targeted to specific aquatic weeds.

Yeah, sure. I'm not a proponent of herbicides anywhere else on our property, so why would I consider dumping huge amounts of chemicals into the very water we swim in? What if the herbicides killed other things besides the unwanted bladderwort, such as beneficial vegetation, frogs, turtles, fish and other wildlife? In total agreement, Ralph and I would rather live with a weed-congested lake than a chemically "pure" one.

Method No. 3 sounded like the only truly applicable option, but would it really work? It involved fish -- triploid grass carp, to be specific -- deposited in the lake to act as living, swimming weed-eating machines.

According to Connaway, the carp, which can be purchased only with a permit from licensed suppliers, consume great quantities of vegetation. In fact, that's all they eat. These sterile swimmers -- they have been genetically altered in the hatchery to prevent reproduction -- live for about 10 years, chowing down on aquatic vegetation like aquatic cows that entire time.

At maturity, they grow to be about 3 feet long and about 40 pounds. That's big!

Ralph and I talked it over and decided on the carp. Unfortunately, I procrastinated. It took another whole year of watching the lake fill up with yet more weeds before I was truly motivated to remedy the situation.With permit in hand, I contacted a local hatchery and ordered our fish. The permit said we could stock up to 110 fish in a lake our size, but being frugal and somewhat wary, we decided to start out with just 75 and see how it went.

On the allotted day, I drove to the fish farm to pick up our purchase. The fish -- 10- to 12-inch youngsters -- were scooped out of holding tanks by hatchery workers and placed inside water-filled plastic bags packaged in cardboard boxes. The boxes were then transferred to the back of my van, and I drove off $600 poorer but with visions of a soon-to-be weed-free lake in my mind. About an hour later, I was home with most of the family on hand to help release the fish into the lake.

That was 13 months ago. Today our lake is the picture of good health. Although the water level has decidedly dropped because of the prolonged drought, the bladderwort infestation has almost vanished. A few rogue weeds still drift by on occasion, and there's a patch about 50 feet by 30 feet in the small end of the lake where a large mass of bladderwort remains, but, in large part, the fish have done their job.

What I can't understand is where they are. I'm out in my boat almost daily, and when I'm not rowing, I'm often swimming or simply looking out at the lake. I see birds and turtles and the occasional gator, but where are our carp? They must be there, because the weeds are seriously reduced, but I never see them.

When I called the biologist to ask that question, he assured me they were somewhere in the lake.

"You should see them in schools, making ripples in the water," he said.

I haven't. But I guess it doesn't matter. Wherever they are, they're probably doing their thing, contentedly chewing up water weeds. I'm happy just knowing we found a satisfactory solution to our problem that was safe for the environment and in sync with nature.

Now, if I can just find a similarly suitable solution to the wild morning glories I foolishly added to my landscape a few years ago . . .

1 comment:

  1. Our neighborhood lake is being taken over by Bladderwort. Are you still successful?