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"Doc" has the grandkids out on the boat, and from the looks of it, they're doing OK with this bass fishing stuff. Don't forget the hats, sunglasses and sun screen, plus plenty to drink, on those hot fishing days.
A recent study provides greater detail on what we already knew was happening, that being the flushing of our stocked walleye through reservoir dams into the rivers below. This study was carried out on Rathbun Lake, Iowa.
Researchers captured walleye in the spillway below the dam and then tagged them and returned them back into the lake. Over the course of the nearly 2 year study, more than 4,000 walleye were tagged and returned. Estimates of fish that made it back down into the river spillway during that time were 26%, or more than a quarter of all the lake's estimated walleye. This number didn't take into account normal mortality rates, so combined loss of walleyes between the two factors is probably much higher.
Researchers did find a few interesting details about the loss;
Since walleyes are known to congregate on rocky dam faces of reservoirs during the spring spawning run, researchers expected to find most of the walleye being flushed through the system at that time. However, models indicated that there was little support of this hypothesis. Instead, mean daily discharge rate was the most influential parameter affecting walleye escapement.
Just because they are releasing some water though, doesn't mean the walleye get flushed. The act of discharge itself seemed to have little effect on escapement during periods of lower flow, but escapement increased exponentially as flow rates increased.
Fish released further distances from the dam tended to have a greater likelihood of staying in the reservoir.
Similarly, walleye length was also an important factor related to escapement probability. It has been suggested that older, and presumably larger, fish have lower escapement rates, and nearly three quarters of the walleye captured in the tailrace and returned to the reservoir measured 12' or less.
Of course, you might also ask what other fish might be getting flushed through our dams and into the rivers below. While it is likely that a few fish from most all species end up outside the reservoir, an older study of a small reservoir with a drop box spillway, similar in design to those on lakes such as Waveland and Glenn Flint, suggested that escapement might be highly species specific.
That study comprised of a typical midwestern fish population found that nearly all escaped fish were either largemouth bass or bullheads. Very few other fish species were ever captured. Largemouth bass went over the spillway during the day, and bullheads went through overnight. Again, timing made a big difference, as most fish seemed to escape during periods of high flow. However, these fish went in groups. You'd get a large number captured over a short period of time, and then despite continued high flow for a short period, no more fish would be captured, suggesting that schools of fish in the immediate area got flushed out and that it would then take a while for the next group to move into the area to potentially get flushed during the next high water event. As an estimate of the total bass population though, these escaped bass represented as much as 1/3 of the entire lakes population.
Similar to the walleye study, most of the bass and bullheads were small. The majority of all the bass caught going through the spillway were between 4"-7". Fish were also observed to easily be able to hold against the current if they chose to, so researchers aren't sure if the fish chose to "go with the flow" . Regardless, both studies reach a similar conclusion in that it's the youngest fish that tend to be lost, and the greater and more prolonged the discharge, such as during very wet springs, the more likely the chance of having lost gamefish fromthe system.
** Estimating and Evaluating Mechanisms Related to Walleye Escapement from Rathbun Lake, Iowa. North American Journal of Fisheries Management; Michael J. Weber, Mark Flammang & Randall Schultz __________________________________________
** Loss of Fishes over the Drop Box Spillway of a Lake. Transactions of the American Fisheries Society. William M. Lewis, Roy Heidinger & Mark Konikoff
Raccoon Bass Anglers would like to thank everyone that came out and fished this event and helped make it a huge success. Thanks to all our sponsors and everyone that participated in this event we are going to be able to donate thousands of dollars to Riley Children’s Hospital. We also have a ton of stuffed animals and toys donated by several teams at the event Saturday. We had 62 boats enter the tournament and several Male/Female and Adult/Youth teams. It was a great day to be on the water and there were a ton of fish weighed in. Once again we would like to give everyone a huge thank you to all the anglers for coming out and supporting this event.
I don't have any great articles to link to, but this pic sent in today by Bob Peters is a good reminder that a lot of nice fish can be caught by fishing after dark now. The standard fare like big buzzbaits, large plastic worms and big single spin spinnerbaits, all in dark colors, are the usual "go-to" baits. This is one area of bass fishing where good old hi-vis mono still has a place. Pull out the black lights and watch the show. Nothing like seeing your line jump while glowing like a light sabre. If you're really adventurious, or have a good net, they'll strike crankbaits just as well. Treble hooks in the dark can be a real safety hazard though. But, it is what this bass was caught on 6-16-13 in Lake County, Indiana, at about 9:30 pm.
They're as rare as a legitimate 5lb. bass, perhaps even more so. Honest-to-God 10 inch bluegills. I landed one last night - made my trip. They're not "just another panfish". You can read one of my favorite pieces on the subject at this Minnesota DNR website link.