Here’s some specifics from an old article I wrote based on discussions with Rob Maher who is ILDNR commercial fisheries chief (I talked with him in late 2003). When he talks about finding “large and robust individuals and lots of them” he is referencing hoop net studies on the Rock river around 2002. Local flathead guide Denny Halgren helped the DNR place nets in a travel route to over-wintering areas in the fall. The DNR aparrently extrapolated their findings resulting in an overly optimistic estimate of how many fish were present. This is because this was the primary wintering area in a very large stetch of river. At least that’s my understanding.
(start)
The DNR employs two sampling methods to assess catfish populations:
• Electrofishing, which gives an account of “young of the year” and smaller cats. This allows the DNR to determine spawning success and overall population data.
• Hoop Net sampling, which specific targets larger blue and flathead catfish to measure those populations.
A few years ago (around 1999, I think), ILDNR used some hoop net sampling techniques to get a handle on the big cat populations. These efforts started with the Rock River, and the same techniques are have been expanded to other large rivers in the state. Trophy catfish population data before implementing techniques to specifically study big cats was sketchy, and often based on anecdotal accounts from fishermen. As Maher explains, “Were really just now starting to come to grips with these big fish. They’re a difficult fish to sample; it’s taken us several years to even figure out how to collect a meaningful number of fish. Were still at the early stages of this catfish management. But, everything we’ve seen is very promising. It’s very impressive the quality and health of the fish – large robust individuals and lots of them.” There was data on Mississippi trophy catfish populations, due to a long-term resource monitoring effort in place there. But, other than that the DNR did not really have a concentrated effort to measure big cats prior to their efforts, which started on the Rock River.
A variety of sampling is used on small streams. The DNR performs “Basin Surveys” working intensively in a specific river basin on a 5 year rotation. They use mainly electrofishing, although there are some netting efforts are going on. Sampling efforts are focused basin by basin on this rotation to be able to collect meaningful data. With the increasing popularity of catfishing, they’re taking techniques developed on big rivers and using on some of the smaller streams with success. Maher confirms that they are in the early sages of assessing all of the interior stream catfish populations. “We have been electrofishing some of the basins for around 15 years, so we’ve got a reasonable handle. We see very good populations on the interior waters also.” This rotation accounts to why annual ILDNR Catfish Status reports don’t always mention smaller streams – the data is generally reported when it is current.
The 5 year rotation reflects ILDNR manpower limitations. They are covering around 6,000 miles of interior streams containing catfish with only 10 Streams Biologists. In addition, there are a few vacant posts currently in the northeast portion of the state. This leaves the DNR spread thin with only two biologists to cover this area, which receives especially heavy fishing pressure. (end)
There was more, but that gives you some flavor of the discussion. Another interesting item is the ILDNR 2007 Catfish Status report, which manages the complete omission of what’s happening with catfish populations on the Fox, Mississippi, Kankakee, Wabash, and Ohio rivers just to name a few. These rivers are some of our more popular fishing areas, close to major population centers like Chicago, St Louis, Quad Cities, etc.
http://dnr.state.il.us/fish/07/07%20CATFISH%20STATUS%20REPORT.pdf
Sorry for the long rant…it seems catfishery management is a much higher priority in Iowa, Missouri, and Minnesota.
Shawn
