NMU grad student wins special recognition for research
By CHRISTIE BLECK
Journal Staff Writer
MARQUETTE — Marquette residents are connected to Lake Superior in many ways, but it should be remembered southern Upper Peninsula residents have their own Great Lake near and dear to their hearts: Lake Michigan.
However, at least two local fisheries aficionados are taking an interest in the more southerly lake, specifically, Little Bay de Noc — and one has a special recognition to show for it.
John Whitinger, a graduate biology student at Northern Michigan University, won for having the best student poster presentation during March’s joint meeting of the Michigan Chapter of the American Fisheries Society and the Wildlife Society at the Treetops Resort in downstate Gaylord.
Whitinger’s poster was titled “Trophic Ecology of Native Sport Fish in a Lake Michigan Embayment,” which included graphs, pictures and detailed information.
In simpler terms, it was about sport fish and the effects certain non-native invasive species have on them.
“We focused this poster on the niche space of northern pike, walleye, yellow perch and smallmouth bass,” Whitinger said.
Brandon Gerig, an assistant biology professor who has Whitinger as one of his students, said the regional meeting brought together fisheries professionals from state, federal and tribal agencies, as well as most of the universities in Michigan where aquatic and fisheries research is being conducted.
It also provided students a way to interact with other students and professionals in the field.
Whitinger said the broader scope of his research is trying to identify the consequences of invasive species on native sport fish populations such as walleye and yellow perch.
“Mainly we’re looking at the impacts from dreissenid mussels and round goby,” Whitinger said.
In more common terms, those bivalves are quagga and zebra mussels.
He acknowledged those mussels are more entrenched in Lake Michigan than Lake Superior, partly because of Superior’s colder temperatures.
Gerig said most invasive species entered the Great Lakes through ballast water from foreign freighters entering the lakes.
“It’s severely impacted all of the lower lakes, with the exception, really, of Lake Superior,” Gerig said.
Whitinger said his research used stable isotope analysis to examine the trophic niche, or the location in the food web, of different species of the fish community.
Stable isotopes, Gerig said, are non-radioactive isotopes.
Whitinger took part in fall gill net sampling with Michigan Department of Natural Resources staff, taking samples from fish muscle tissue.
“We look at them for carbon and nitrogen,” Gerig said. “Carbon allows us to differentiate where they’re getting their energy from so you can distinguish between, say, the offshore food web and the nearshore food web, and then nitrogen provides an indication of where that species fits within the food web so we can separate out our lower-level organisms, like a dreissenid or zebra mussel, from an intermediate small prey fish, like a juvenile yellow perch, from a large apex predator like a northern pike.”
He said the NMU samplings will act as a “tack-on” survey to the DNR’s work to provide more information on the fishery and possibly improve its management.
Many undergraduates helped support the work as well, said Gerig, who noted the samples are processed at an NMU laboratory and then mailed to Cornell University where they are analyzed in its stable isotope facility.
Whitinger already has preliminary results.
“A lot of the fish species fell within the ranges of carbon and nitrogen that we would have figured with the exception of Eurasian ruffe and black bullhead and a few others that showed really negative carbon values, indicating that there’s probably another source of carbon that they’re utilizing,” Whitinger said, “which I don’t think has been documented in Lake Michigan previously.”
NMU researchers suspect fish are consuming non-biting midges living in sediment that feed off methane-producing bacteria, and that methane is the other source of carbon, he said. However, more samples are warranted.
He said the finding is significant because it shows certain species, especially Eurasian ruffe, are using a prey resource others aren’t using.
However, Gerig said that maybe the biggest takeaway from the poster is the possibility at least four sport fish of note are converging on the same area.
“It would suggest that walleye, northern pike, smallmouth bass and, to a certain extent, yellow perch are all receiving their energy from kind of a pretty narrow range,” Gerig said.
NMU researchers are hypothesizing that because round gobies have become an abundant part of the food web, or the lower prey fish community, there might be a dietary reliance on the non-native gobies, he said.
So, there will be more investigation into the kind of linkage between invasive prey fish and native sport fish, Gerig said, since the belief is that almost all of the native sport fish are consuming lots of the invasive fish.
“Now that there’s this abundant goby resource, if those native fish are taking advantage of it, it could actually be a good thing,” Gerig said. “So, we’re trying to evaluate what the kind of reliance is of these native fish on this invasive species, and how perhaps they’re at least helping prop up these native fisheries that have been hit pretty hard from some of the invasive mussels.”
Christie Bleck can be reached at 906-228-2500, ext. 250. Her email address is firstname.lastname@example.org.