Saturday, May 10, 2008

Plant Eating Fish

Thousands of plant-eating fish released in South Florida.
For thousands of grass carp making an overnight move to South Florida in March, the relocation offers a promising future-access to a lifetime's worth of food in canals along Florida's lower east coast maintained by the South Florida Water Management District (SFWMD). The sterile fish do not breed, so instead they can focus all their ener­gies on eating hydrilla, a rapidly growing invasive plant that slows water flow and can clog structures in SFWMD canals that must be kept clear for effec­tive flood control. District scientists released 19,500 hydrilla-eating fish into area canals. Since hydrilla was first introduced as an ornamental aquarium plant in the 1950s, the rapidly proliferat­ing plant has invaded most of Florida's ponds, rivers and waterways.

The plant can grow in under­water stands or surface mats and is easily trans­ferred by boat traffic. To combat hydrilla, the District has been stocking its canals with grass carp for nine years as part of a successful bio-control program that helps to reduce the need for more expensive chemical treatments.

This year, the District will invest about $150,000 to purchase 51,000 grass carp to stock canals from Fort Lauderdale to Homestead. In contrast, a single her­bicide treatment in the North New River Canal would cost $230,000 and provide only short-term hydrilla control. This grass carp species, native to Asia, is farm-raised in Arkansas.