Cell analyser used to control fish stocks

It uses the 'electrical sensing zone' method (also known as the Coulter Principle) to determine the size, number, concentration and mass of a wide variety of organic and inorganic materials.

The grass carp, a large herbivorous minnow from lowland rivers of eastern Asia, is used as an inexpensive, long-term method to control the over-growth of submerged aquatic plants.

Grass carp, like most fish, are diploid.

They possess two sets of chromosomes (one from each parent) and are capable of sexual reproduction.

The potential of the diploid grass carp to naturally reproduce, and eventually over-populate ponds, caused considerable controversy over its use as a biological control agent.

This risk eventually led to the development of a method for the production of non-reproductive, triploid grass carp, that have three sets of chromosomes and are incapable of normal sexual reproduction and the production of viable offspring.

Concern exists, however, that induced polyploidy could result in a small percentage of reproductive grass carp.

The US Fish and Wildlife Department requires anyone that produces and sells grass carp to perform inspection and 100 per cent triploid certification to ensure that the grass carp are non-reproductive.

This is done by measuring the volume of the nucleus of a red blood cell after the cell membrane has been chemically removed.

The only way to accomplish this is with the 'electrical sensing zone' method, the analytical technique accepted by the US Fish and Wildlife Department as well as other global agencies.

The Elzone II inspection tool can quickly differentiate diploid from triploid grass carp.

Fast analysis and low noise features have been designed into the Elzone II to meet the needs of the grass carp industry.

A real-time pulse display with automated cursors clearly distinguishes ploidy.

Live histograms are also included.