AKRON, OH- Ohio anglers are always happy to catch a creel full of slab bluegills, a live well full of hawg largemouth bass, or that Fish Ohio! walleye they have been searching for all summer. However, none of these fish would be capable of growing to harvestable size if it wasn’t for organisms that are smaller than the period at the end of this sentence. But who is looking after those microscopic individuals?

Throughout July, fisheries biologists from the Division of Wildlife will be looking at those organisms that young fish consume. Throughout Northeast Ohio, 33 lakes will be sampled to determine the composition and amounts of nutrients, phytoplankton, and zooplankton in the water. Matt Wolfe, fisheries biologist for the Ohio Division of Wildlife, explains what they are searching for. “Think of it in terms of a food pyramid. Animals and plants feed on whatever food level is below them. In Ohio lakes we know that big fish eat small fish, but what are the small fish eating? That is why we sample what the small fish are eating (zooplankton), what the zooplankton are eating (phytoplankton), and what phytoplankton utilize (nutrients). “ Wolfe said. In the past, biologists focused on the upper levels because that is what anglers caught. But these lower trophic levels are just as important. “The right amount or type of zooplankton, phytoplankton, or nutrients can determine the strength of a year class for many different types of fishes.” Wolfe added.

The field work involved in examining these trophic levels is fairly simple. Biologists will take a water sample over the upper 6 feet of the water and then freeze a small part of it to look at the nutrients, filter some of the water to examine the phytoplankton, and preserve some of the water to look at the zooplankton. Dissolved oxygen and temperature readings will also be recorded to see how the reservoir is stratifying and warming. Once all of the information collected, biologists will then look at patterns of fish survival and recruitment on a statewide level.