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Thursday, July 5, 2018

Central Stonerollers

If you are a river rat here in the midwest a baitfish that should really be on your radar is a little guy called the central stoneroller. These guys occur in many of our streams in staggering numbers. In my neck of the woods, Southwest Ohio, most of the tributaries to the Great Miami, from small ones up to big ones like Twin creek are dominated by central stonerollers. They are the most common fish in the tributaries to the Little Miami as well and almost without exception all the fishable creeks that run into the Ohio River have anywhere from 25 to over 50 percent of all fish caught in studies being central stonerollers. For example in one electroshocking study conducted by the EPA on Big Indian creek 1896 total fish were shocked. That includes carp, suckers, bass, everything. Well out of 1896 fish, 1116 were stonerollers! And sometimes the numbers go off the scale... in O'bannon creek 4,352 were shocked up in one location, 3,005 at one place on Todd's Fork, 2271 at another and 5227 at another spot on the fork. Just to put it in perspective it's usually a pretty big number if they shock up 150 of some darter or shiner in one location.
So having established that this fish is the king kong of the food chain on many of our streams lets learn a bit about it. Central Stonerollers are benthopelagic fish which can float in the water column just above the bottom. (this is going to play into how we imitate them so remember this part) Benthopelagic fish have neutral buoyancy, so they can float at depth without much effort. The reason for this is the way stonerollers feed. The central stoneroller is mostly herbivorous, feeding on algae scraped from rocks and logs with the spadelike cartilaginous projection of its lower jaw. Young fish feed on rotifers (google these guys! they are fascinating in their own right), filamentous algae, and microcrustacea. Adults also feed on detritus, diatoms, and once in a while aquatic insects. It is classified as a grazing minnow in its feeding behavior, and large schools of these fish often feed together. Central stonerollers may consume up to 27 percent of their body weight in algae per day. One Kansas study found that algae contributed most (47 percent) to the diet of central stonerollers, followed by detritus (30 percent), animal matter (21 percent), and terrestrial vegetation (2 percent). I guess you could go on and on trying to figure the impact of millions of fish eating 27 percent of their own weight in food every day and how that has to add up to an incredible amount of poop enriching the food chain and on and on but I think I'll just stop with they eat a lot and there's a lot of them and smallmouth love to eat them. Stonerollers don't really seem to compete with other fishes in the stream but instead convert algae into tasty smallmouth and catfish food. If stonerollers compete with anything I'd think it would be crayfish and I'd love to see some studies on how they compete and interact with each other.
So why in the world are they called stonerollers? Well lets look at a year in life of our tiny heroes to find out. In late winter and early spring male stonerollers begin to dig out spawning beds just above and below riffles. They do this by rolling away tiny stones and gravel out of the bed with their snouts. Hence the name stoneroller. Male stonerollers are very territorial and will viciously attack other males that venture too close even to the point of driving them out of the water and up on the bank. I've not seen this but the guys who study stonerollers swear it's amazing. Meanwhile as spawning nears the lady stonerollers begin to swim in and out of all the nests looking over the guys. At this time lady stonerollers will often jump straight up out of the water like a mini carp. This I have seen. So far I don't think anyone has come up with a good reason for this behavior. Supposedly the biggest males with the best nests get all the ladies. Eggs are then laid in the nest fertilized and once spawning is complete the males say "whew" and just swim away and forget about the nest they have built and fought over all spring. But when the male fertilizes the eggs his, umm, stuff causes the eggs to become sticky and they stick to the nest where they hatch in three or four days. I also remember reading that male stonerollers were pretty OCD when it came to their nests and from late winter till the spawn never quit working on them compulsively. They didn't really get a lot bigger but because of all the rolling and movement the nest kind of wandered all over the bottom in the same general area. I always picture this filmed with one of those time lapse cameras so that in 20 seconds you can see the nest move all around even though it took two months in reality.
During the spawn male stonerollers get a bit more colorful with orange tinting to their fins and they grow little bumps or tubercules all over their heads and scattered randomly over their bodies. I'll include some photos at the end but it's safe to say what's sexy to a stoneroller is a bit different than our idea of sexy.
So once the spawn is over everybody returns to ghosting over the bottom and tipping up every now and then to scrape some yummy algae off the rocks. So we don't want our stoneroller imitation right on the bottom or high in water column but instead swam slowly just off the bottom. Or as I like to say the classic grub or swimbait retrieve. But what do they look like? How big are they?
Well stonerollers are stout round minnows with the biggest part of their bulk kind of in their front half. They are not the classic flat minnow lure shape like shad or shiners but very round. They can get pretty big for a minnow, too big for smallmouth sometimes at seven or eight very stout inches but the vast majority are from two to four or five inches long. In other words just right for a nice meal if you are a smallmouth. Except in breeding season stonerollers are a mostly brownish with a bit of olive mixed in colored minnow that is much lighter on bottom than the top. The males are generally bigger than the females and so I think most in the sizes smallmouth would eat are plainer in color.
For most of the year I try to imitate stonerollers with Vic's paddletail you see in the photo. In fall I'll also fish a brownish or motoroil grub to imitate the jillions of young of the year stonerollers in the stream. Well anyways that's my spiel on stonerollers and hopefully if your stream is one of those dominated by stonerollers you will try swimming a grub or swimbait right off the bottom and see if it ups your results or possibly even the size of the fish you catch. After all stonerollers are hefty little fish and just the thing to fill the belly of a big smallmouth...

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