Long Trawl Yields Big Data Haul

Really, any way you cut it, it’s a lot of time to spend on a boat, collecting and counting fish.

But that’s how Titus Seilheimer, Wisconsin Sea Grant’s fisheries outreach specialist, spent large chunks of his time over the past year, in the service of a research project aimed at determining the effects of the use of whitefish trawl nets by commercial fisheries in the Two Rivers/Manitowoc area of Lake Michigan. Working with the Steve Kulpa and Susie Q Fish Co. on the midsize trawler Peter Paul, Seilheimer surveyed the catches collected by a whopping 491 drags over those 65 days, tabulating the whitefish and the bycatch and tagging certain fish for tracking purposes and survival estimates.

Seilheimer was surprised by the lack of actual bycatch the trawl nets collected. Lake trout and sublegal or unmarketable whitefish constituted the majority of non-whitefish bycatch. Other species were encountered too, like burbot, white sucker and round whitefish, but there were very few sport-fish species (three Chinook salmon and one brown trout). Over the 65-day study period, the amount of bycatch landed was less than 3 percent.

That’s a potentially critical finding for the future of whitefish trawling in the Two Rivers/Manitowoc area, a practice that’s currently not allowed under state law. (The Wisconsin Department of Natural Resources granted special approval for the Peter Paul to trawl in a limited area for this study.) In the 1980s, trawling for alewife and smelt, along with experimental trawling, resulted in both heavy bycatch and bycatch mortality. Preliminary results from Seilheimer’s study indicate that changes in the lake, such as increased water clarity, may be a factor in the changes in bycatch.

The early and long hours weren’t the only challenging aspects of this particular research project. Turns out wrangling and tagging sizable lake trout by hand isn’t as quick and easy as it looks. The other Herculean aspect isn’t quite so piscine — it’s the magnitude of the data Seilheimer collected. He now has figures charting everything from the number of whitefish caught in each month to the size range of the lake trout in the bycatch and where some of those lake trout went after being released. One tagged lake trout was eventually discovered more than 300 miles away in the Canadian waters of Lake Huron.

While the first round of data collection is now complete, the trawling project will continue into a second year, this time featuring trawls at depths that are natural rather than experimental. The Peter Paul now has a video camera system installed to monitor the catch and bycatch.

“I’m glad we’re going to be able to continue this research,” said Seilheimer. “It’ll just be without me on the boat so much.”

Goby Creep Closer to Lake Winnebago

Nobody expected they would get quite this far quite this quickly.

Then again, the invasive round goby has made a comfortable career out of confounding conservationists and researchers’ expectations, so the fact that they’ve now been found in Little Lake Butte des Morts near Neenah and Menasha — just below Lake Winnebago, one of Wisconsin’s premier fishing lakes — shouldn’t necessarily be surprising.

Alarming, though? Absolutely.

Gobies were first discovered in the Great Lakes region in the early 1990s, and they had set up shop in all of the Great Lakes by 1995. But as recently as a few years ago, research funded by Wisconsin Sea Grant seemed to indicate that they weren’t migrating to colonize Wisconsin’s inland waters.

“For 20 years, we managed to keep them in the Great Lakes,” said Tim Campbell, invasive species outreach specialist for Wisconsin Sea Grant and the University of Wisconsin-Extension. “We did a good job.”

To look at them, the bite-size gobies don’t seem like a predatory threat, but in every environment they’ve entered, they’ve created massive disruptions in the food web.

“Lake Winnebago is a world-class fishery, creating some $200 million in economic benefit,” noted Campbell. “Gobies will clearly impact that in some way. As a fisherman or a nature lover, I’d be concerned about that, especially considering Lake Winnebago’s unique sturgeon fishery.”

It’s illegal under state law to possess and transport round gobies, but it is suspected that the main way gobies are getting closer to Lake Winnebago is from bait bucket release, which explains how they could bypass multiple locks and dams to arrive in Little Lake Butte des Morts.

To put up another barrier to the goby invasion, the final lock between Lake Butte de Morts and Lake Winnebago has been closed for now. That’s good news for preventing the spread of an invasive species but also carries a heavy impact for recreational boaters and the businesses that cater to them, as there’s no longer a way for boats to get from one lake to the other without trailering.

To help mitigate those impacts, options to operate the lock while keeping gobies from passing through are being investigated by the Department of Natural Resources and the Fox River Navigational System Authority.

In the meantime, Campbell’s hired several graduate students to help spread the word about avoiding bait bucket release this fishing season. The outreach is valuable, but vigilance is even more key. After all, it only takes one release to unleash the goby.

Becoming a Force for Nature

Earlier this year, Wisconsin Sea Grant became a Weather Ready Nation ambassador. Weather Ready Nation is a National Weather Service initiative to, among other things, help individuals and families develop a comprehensive plan for extreme natural situations as well as perhaps less severe but still troubling occurrences such as power outages.

Being ambassador means Sea Grant is part of a force multiplier bringing together business, academia and nonprofits to be ready, responsive and resilient. Both Sea Grant and the National Weather Service are housed within the federal department known as the National Oceanic and Atmospheric Administration and, for the past several years, Wisconsin Sea Grant’s social scientist, along with others, has been helping to refine language used to warn local residents of hazardous weather in their areas.

See go.wisc.edu/49e903 for more information

The Aquatic Sciences Center is the administrative home of the
University of Wisconsin Sea Grant Institute & University of Wisconsin Water Resources Institute.

©2011 University of Wisconsin Board of Regents