From Joel:
We are committed to at least a 4 year project.
The major goals of the Tagging and Diary Project.
1. The St Croix River has more liberal catfish regulations and we don’t know if that is a problem. We have received some complaints over the last five years that there aren’t big catfish in the St Croix anymore (although we have seen some pictures of some hefty fish). Only standard sampling efforts have been conducted on the St Croix (with the addition of trot lines to sample catfish) but not enough fish have been caught and not enough information has been collected to know if there is a problem. That’s how all of this started.
2. To acquire better information about catfish angling effort and harvest. Our standard creel surveys will miss many catfish anglers, and catfish anglers are something we know very little about in the metro. I started working on this project last year and figured with tough times forecasted, we likely would not have the money to run a creel survey on the area’s rivers. I think the most recent one we had was on the St Croix in 1998. And we likely will never have a creel survey that targets catfish anglers because of the difficult schedule that would be required and the safety concerns and difficulty seeing bank anglers when running a river at night (let alone in metro).
3. We don’t have a clue as to how many catfish are actually out there. By doing a mark-recapture tagging project, we can estimate the size of the population like we are doing with lake sturgeon. However, we obviously are going to have a lot more catfish than sturgeon out there and my hope is to tag as many of these catfish as possible. The more fish I tag, the less error in the estimate.
4. We don’t know how far these fish move. Tagging studies have been done and are being done around MN that show how far and how little some catfish move. We have not done it here and we need to know if fish are moving between rivers, staying in short stretches, or moving long distances. We also would like to get a hold on where these fish overwinter. This is particularly important because when these fish stack up in winter, they could be susceptible to over harvest or illegal snagging. If every catfish for 10 river miles ends up in one hole, that’s a big deal. This is where the angler tag returns becomes invaluable information. I’m going to be sampling by electrofishing, netting, trot lining, and whatever else I can think of that will get me numbers of fish. Using angler tag location data will greatly improve the movement data, especially if a lot of anglers are helping out with it. That many more hooks in the water, spread out over that much more water. A catfish tagged in Pool 2 might make a crazy run to the St Croix and cover 50 miles in two weeks, and I might never know it unless an angler happens to catch that fish and report where it was caught. Ideally this movement information would be conducted with radio tags, but I was planning for tough times and this is a cheap way to collect a lot of information.
5. Sub samples of these catfish will have tissue removed for genetics testing. We need to know if we have distinct populations of catfish that are not interbreeding or if stocking that has been done over the years has mucked things up. Channel catfish above St Croix Falls Dam have not mixed with the cats below, but it is possible enough genetic drift occurs from fish going over the dam and breeding with the lower population. St Anthony Falls was originally a barrier to catfish travel both naturally and when it was dammed in the late 1800’s. It was not passable with a functioning lock and dam until 1956, then fish could pass. Coon Rapids Dam was originally built in 1913. Catfish did not originally inhabit the Mississippi River above these points and many stockings took place in the 70’s and 80’s. Most of those catfish came from a federal hatchery in Ohio. There is even more background information on this that most people don’t want to know and it’s long enough already.
6. We haven’t done any catfish aging in the metro rivers. I did a flathead survey last year on Pool 2 and took pectoral spines from 117 flatheads (also took channel cat spines in other surveys). Not all of the fish have been aged yet, but what I’ve seen so far is that flathead catfish length at age is highly variable (6 year old fish range from 16-26 inches long) and the oldest I have seen has been 25 (and that was only a 36 pounder, I haven’t aged the 50 pounder yet). And that 25 is likely under aged as I was using a spine and not an otolith. Sub samples of the fish tagged will also have a spine removed for aging. Any accidental mortalities will also have otoliths removed. There is a paper published that stated no mortality occurred in their study when spines were removed. Were hoping to confirm that over a longer time frame.
I’m sure I’ve got some other “here’s something else we can look at” ideas that I am forgetting about, but the ones listed above are the main goals driving the project and that is enough information to digest.
As BK mentioned, please post any questions here and I’ll address them as they come up.
Joel Stiras
