Migrating Darters

Well since it seems everyone is so enthusiastic about starting new threads I thought I would jump right in . I recently was in a stream a few weeks ago and caught nothing but redlline darters. I recently returned to that stream and it seems all I could catch was Tennessee Snubnose. What happend to all those redlines. And when I was catching those redlines I mean that is all I was catching and lots of them. Do Darters migrate for spawning this time of year? Were those redlines just passing through at that particular time to go to their spawning grounds upstream like a salmon or something?? I just thought this was an interesting thing I observed. Anyone else observe this in their collecting of darters???

Many species of darters have been found to make "migrations" (small to relatively large) amongst areas of seasonal habitat. For the most part, adults do not make such long distance trips like salmon. They were likely in an area of different habitat near by where you sampled. Also, Redline darters and others closely related to them, do not spawn until the summer.

Darters (really all fishes) will make lateral migrations through the year depending on what resources they need at the time. Because you "never step into the same river twice" as the old saying goes, so the same, the resources at a locale may no longer meet the requirements a species needs.

This can even change on a very local scale, where under certain flow conditions, you were catching a certain species, or all species near shore (esp prevelant in flood conditions), but find their spatial placement far different at a different flow condtion.

This goes even further, especially with darters, with what ecologists call the "partitioning of habitat resources". I mean why do we find all these species of benthic oriented species conglomerated together? What's the force that allowed speciation to happen? If you don't have a condition that's applied, what's the point in adapting?

With this in mind, you can build a spatial model in your head where species will be located. In your area, depending on the stream size, let's say one that's about 20 feet across.... In a riffle sequence you'll find:

• snubs and bluesides in the shallower portions of the riffles with the snubs more oriented to rock and the snubs more oriented to sand
• rainbows and bandeds in the moderate mixed flow with no clear delineation to my eyes
• redlines in slightly deeper higher flow
• logperch out in the high discharge stuff

And this will hold true with the endemics in the Duck, Collins, Caney Fork, etc.

What's crazy, is a place like the Duck at Shelbyville, where to my eyes, it's one long gravel run and the only differences I see are in the volume and velocity of the water. Yet you can get like 12 darter species there? Maybe it's the dam? Maybe because the sediment conveyance has been interrupted, the same habitats are there all the time (which isn't necessarily a good thing), and I just can't see those portions of the stream at the levels when I've sampled?

This is where dams can mess up darters too. If they can't migrate to the prefered habitat, they're stuck with what they have. Sure, the species count immediately below the dam is great, but what is the actual potential up and downstream of that point, and how much of that potential is being utilized?

People will get their shorts in a wad when you want to pull a dam because they could always go to that dam (or a spot just downstream) and find the same species in the same habitats. What they don't realize is that it's only a marginal habitat, that the biological potential of the stream, if the fishes are given their choices of habitats, is an order of magnitude greater than what they are observing.

A fella I'm learning stream restoration techniques from hears it all the time... "I used to catch smallmouth right there until it all silted in" and Dave tells them "yeah, but you can catch those same fish and even more according to our DNR surveys, just have to find where they moved to" and the repsonse is: "Yeah. But I can't catch them THERE any more." {insert jet airplane noise flying over your head}

At any rate (and back to your question), this is something to consider while you're out, and make more observations about. Conceptualize the stream you're working into a simplified model. It'll also help you target species, or identify habitats that you should work.

For example, I was in the Chattanooga area once, saw a weird sand run that was out of the normal, said "there could be snail darter THERE" (which my friend looked at me like I was insane)... And well, there were. In fact, looking back upstream having now identified the habitat, I saw that this spot was actually a MARGINAL habitat, and we walked in, and in 4 seine hauls had a couple goregous, breeding condition males.

Todd

rainbows and bandeds in the moderate mixed flow with no clear delineation to my eyes

I take this back. There is a delination, and it's the placement of the mouth, and how they extract food from the habitat as the partition, instead of the habitat itself. Same with the snubs and blueside.

Todd

Todd is pretty much on the ball about the partitioning of habitats within a stream along with his Tennessee examples. Most of the streams I've sampled in TN in the last two years follow that pattern. I have noticed that in early March, Redlines (and Bluebreats and Woundeds for that matter too) were alot deeper compared to May-September.

Must you keep rubbing it in that in an hour you got half as many snail darters as I did after about 400 unit efforts up and down 10 miles of that stream #036; It scored you a citation in a manuscript though. I bet your substrate was 2-32 mm with some 32-64 mm particles thrown in, about 0.4-0.6 m in depth, and 0.5 m/second velocity. If I go see Casper at the end of the month we're going RIGHT back there so I can see exactly what shoal it was.

I take this back. There is a delination, and it's the placement of the mouth, and how they extract food from the habitat as the partition, instead of the habitat itself. Same with the snubs and blueside.

Todd

I went out last Monday to collect 15 black darters from Limestone Creek in AL for Tom Near. We found all of them in relatively slow moving water on the edge of faster riffles, in rock and sand substrate, in water no more than knee deep. The rainbows and stripetails we found were in faster flowing water, deeper if anything. The delineation is always more precise than one would think. The fun fish we seined was a brook lamprey about 20 cm long. My students had never seen a live one before so they were impressed, and as I always do with stream lampreys I let it go...

Must you keep rubbing it in that in an hour you got half as many snail darters as I did after about 400 unit efforts up and down 10 miles of that stream #036; It scored you a citation in a manuscript though.

Mmmmm... Todd Crail, pers. comm.

Man, it was too bad I wasn't set up to do anything more than a hand shot. Same with the ashy.

If you end up thisaway, I'll have to drag you back down. I want to get into Caney Fork and see these bloodfins in the wild. My male is immaculate right now, I can't wait for the water to warm up! Would love to get some underwater footage of those beasts.

What I really wonder about, is how big these greenfins have to get before they color up? The large male I keep is the size of the maxed out bloodfins and he's still not showing color. Prolly see those in the Watuga and Nolichuky, right? My fish are from the French Broad in Ivy Creek north of Asheville.

I must say I think the redlines came up, spawned, and then headed back down to the larger Chickamagua creek. I went farther up that stream that I ever did in search for them and I could not find a one. I ran into a makeshift dam some well meaning people made and there is no way the darters could have made it up and over that so that was the end of my search. I still hope to get more some day. I shipped some to a friend and a bad thing happened. Some water got out of one or more of the bags somehow and wet the newspaper and it must have suffocated them in the breather bags I use to ship in. I was realling hoping to surprise him with redlines instead I disapointed him with dead ones. Well wish me luck in my search and any tips or clues would be a help if anyone knows where or what they may have done. Snubnose and rainbows are all I see now in that stream.

Well a good Easter to all and enjoy the season with family. A great time of year it is. I start to enjoy another passion of mine and that is wildlife, landscape and wildflower photograhpy. My son recently purchased a Canon S3-IS digital camera. What an awesome technological machine. I use a digital slr myself. Since I grew up in the film era I am much more comfortable with the control a DSLR gives you. It acts just like a film camera only digital. And I have six gigs of storage so I can shoot in the field till my hearts content and It does not cost a cent. That to me is one the good aspect of digital. I enjoy photography much more now. You can experiment with different exposures, depth of field etc etc and it does not cost every time you push the shutter release.

Take care,
Daniel

Daniel,

Redlines don't being to spawn until June and go throughout the summer. They really like the warmer weather. Them not being there at that very day is more likely just coincidental. Were you looking for the redlines in the fast riffles? Snubs and redlines are rarely found in the exact same habitat, so if you're getting snubs or rainbows, look for faster water and bigger rocks to kick. You'd be surprised what barriers small fish can get over too, especially in higher water events. It seems as though people in Tennessee are predisposed to build dams though because nearly every small stream I sampe, middle or east, there is always one small homemade rock dam.