[NJSquatch]

What is a Triploid Grass Carp? http://www.dec.ny.gov/outdoor/7973.html

In 1983, US grass carp producers began production of a sterile (triploid) form of grass carp, mitigating the reproductive concerns associated with the diploid fish. Triploid grass carp are created through shocking grass carp eggs immediately after fertilization with either hot or cold water. This temperature shock results in the retention of an extra chromosome set, rendering the fish incapable of producing viable young. With the exception of this extra chromosome set, triploid grass carp are identical to their diploid counterparts. They can live 10 years and grow to 25 pounds.

Triploid grass carp have distinct feeding preferences, preferring tender, succulent plant species over those that are tough and fibrous. Triploid grass carp will not control emergent species such as cattail or bulrush or floating leaved species such as water shield or water lily. Even among preferred submergent plant species, selectivity and consumption rate varies widely according to a vast array of factors including water temperature, dissolved oxygen and presence or absence of attached algae.

Triploid grass carp are extremely potent plant consumers. If overstocked, they are capable of eradicating all plants from a pond for periods exceeding 10 years. Besides the obvious impact such complete plant removal will have on vegetation-dependent fish and wildlife, total devegetation of a pond can also result in the development of severe algae blooms, foul smells and an overall decline in water clarity. To minimize or prevent such adverse impacts, plant populations should be maintained at approximately 20-30% of the pond's surface area.

Due to various factors that impact triploid grass carp feeding, it is impossible to precisely predict the exact number of fish to stock to achieve the 20-30% plant coverage target. The only way to prevent excessive plant control is through use of an incremental approach. This approach involves the stocking of triploid grass carp at the stocking rates suggested below, followed by a two-year waiting period for the fish to achieve maximal control. Then, if needed, more fish are added in small increments at two-year intervals until plant populations are reduced to the 20-30% threshold.

Recommended Initial Triploid Grass Carp Stocking Rates
Average Plant Density / Stocking Rate (# of fish per acre)
Low Plant Density / 5 fish per acre
Medium Plant Density / 10 fish per acre
High Plant Density / 15 fish per acre

Lake hopatcong is around 2,500 acres with approximately 30-40% of that area being less than 15' where the weeds will grow.