Barbs and Backlashes

“Blinded Me with Science”–December 2009 by Nebraska Game and Parks Commission
December 21, 2009, 3:00 pm
Filed under: Fishing | Tags: , ,

I have another summary of some fisheries research work that has been done in Nebraska.  We had a major Aquatic Habitat Rehabilitation Project that was completed at Sherman Reservoir a couple of years ago,  Part of that project included the addition of rock rip rap to protect shorelines and bays and there were also some walleye spawning reefs placed just south of the dam.  Jordan Katt spent a couple, three years evaluating the use of those spawning reefs as part of his Master’s research at the University of Nebraska–Kearney.

Jordan recently presented a seminar on his findings, Response of Walleye to the Addition of Spawning Substrate in Sherman Reservoir.  He found that the walleyes did in fact use the new reefs as spawning habitat.  After those reefs were completed they were used the most in the first year they were inundated.  The second year there was less use of the spawning reefs.  No one knows for sure why the walleyes used the reefs less in the second year, but it was believed that water levels were higher the second year and therefore the spawning reefs may have been too deep for walleye spawning.

Ideal walleye spawning habitat is cobble-size rocky substrate in water less than 3 or 4 feet deep.  There are hardly any Nebraska waters that have ideal spawning substrates for walleyes, but they will use the next best thing and that is the rocky or soil-cement substrate on the dam faces of most Nebraska reservoirs.  By far the greatest concentration of walleye eggs were deposited on the face of the dam at Sherman during Jordan’s research.  Walleye eggs were as dense as 390 walleye eggs per square meter per spawn night!  That is a darned lot of walleye eggs!  There was variability in the timing and amount of eggs deposited from year to year probably due to weather and water conditions.  Walleyes typically produce big year-classes only once every 3-5 years whether those walleyes have been stocked or produced by natural reproduction.  Previous work at Sherman has indicated that we have significant natural reproduction there, maybe enough to maintain that walleye population, but we continue to stock anyway.

I took special interest in Jordan’s project because I have spent some time overseeing some of the walleye projects being done in the state, and I was privileged to spend some time a couple of springs helping Jordan with his field work.  There were some long, hard, cold days and nights doing that work, (including one night when the boat motor konked out and we drifted all the way across the reservoir!), but it is always neat to see it all come together.  We know the walleyes will use man-made spawning reefs and those habitats can contribute to the natural recruitment on those waters.  We do not know if the walleyes will continue to use those reefs over time, nor do we know if we can increase natural recruitment to the level where stocking is no longer needed.  We also do not know if older, larger walleyes occupy the best spawning habitats and push younger, smaller fish to more marginal spawning habitats?  Scientific research always produces more questions than it answers.


1 Comment so far
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Very interesting! Sounds like a good time

Comment by Diana

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