Why Does a Fish Hatchery Need a Particle Counter?
BY NATHAN ECKERT, GENOA NFH
Recently Genoa National Fish Hatchery (NFH) purchased a Beckman Coulter Multisizer 3 (MS3) instrument to aid with fish and mussel culture at the hatchery. A MS3 is an instrument that is capable of both counting and measuring all of the particles in a sample of water. Depending on the aperture tube installed in the instrument it can measure particles from 0.4 microns all the way up to 1.2mm.
The purchase of this instrument signals the beginning of a serious effort to culture juvenile freshwater mussels on-station as opposed to our previous efforts which focused almost exclusively on growing our juvenile mussels at offsite locations. Juvenile freshwater mussels feed on particles from 0 to 15 microns. In a captive culture situation we will use the MS3 to monitor the amounts of food particles available in our juvenile mussel culture systems. Maintaining appropriate food levels will decrease water quality issues that can result from over feeding, as well as preventing loss due to starvation. These improvements should increase survival of newly metamorphosed juvenile mussels in captivity, a life stage that is highly sensitive to water quality issues and prone to mortality events.
Another potential use for the MS3 at Genoa NFH is to monitor zooplankton levels in our walleye culture ponds. It is known that walleye fry grow rapidly on a diet of rotifers and cladocerans. In the past we have counted these animals from water samples by hand under a microscope. With an adjustment to the MS3 we will be able to run a sample of pond water through the instrument and determine not only the density of zooplankton in our water, but also the size range of those animals as well.
It is our hope that with the purchase of this instrument we will see gains in both fish and mussel culture at the hatchery.