Barbs and Backlashes

“Blinded me with science”, Feb. 25, 2010 by Nebraska Game and Parks Commission
February 25, 2010, 2:41 pm
Filed under: Fishing | Tags: , ,

Let me give you another summary of some Nebraska fisheries research that has been done and some that is still ongoing.

Our Game & Parks headquarters office sits on the west edge of the East Campus of the University of Nebraska here in Lincoln.  We frequently interact with the wildlife and fisheries professors and their students which are also here on East Campus.  I will admit that I do not get to spend as much time keeping up with fisheries research and all of the fisheries professional literature as I would like, so I love the opportunities we have to interact with the faculty and students here at the University of Nebraska.  I am always learning something from them.  A couple of those guys came over a few weeks ago to give us an update on some research that is still in progress.

The first project involves fish recruitment in irrigation reservoirs.  Jason DeBoer gave us an update on the work he and others have been doing on our southwest reservoirs–Year-class strength of fishes in irrigation reservoirs:  Importance of relative hatch times.  Water levels on Nebraska irrigation reservoirs typically fluctuate dozens of feet annually.  That water level fluctuation can have significant impacts on fish populations and those impacts can vary from species to species.  Jason and others are trying to find how those fluctuations impact recruitment of different species of fish.  Their work is still in progress, but a quick summary of what they have found so far indicates that the greater the fluctuation in water levels from year to year the greater the fluctuation in walleye and white bass recruitment (I should define that term “recruitment”, you can think of it as reproduction, but to biologists “recruitment” more specifically means the addition of new fish to a population.  It may not be just reproduction because it may be more meaningful to define recruitment as the addition of new adult fish, or addition of new catchable-size fish.  If we are talking about the recruitment of new fish to the sport fishery then fish have not recruited until they survive and grow large enough for anglers to catch).  Water level fluctuations do not necessarily mean poorer recruitment because you can still have some big year-classes produced.  What they have found so far is the more water levels fluctuate the less stable/more variable walleye and white bass recruitment.  They will continue to study those recruitment patterns and try to determine what variables have the largest influence on recruitment.

Let me add one editorial comment here–I have always said that if we could manage water levels in reservoirs for fish production we could have more consistent and overall better fisheries.  I know that is a fantasy because water levels are going to fluctuate in irrigation reservoirs.  Just keep in mind that the fisheries we have in irrigation reservoirs are at the mercy of those fluctuations.

Dr. Kevin Pope and other students are in the middle of a study to better understand angler motivations and behavior–Catching Managers, Anglers, and Fish.  They are lo0king at a variety of questions about angler behavior and how that is influenced by management activities and the health of fisheries.  Models have shown that good fishing can recruit more anglers (Duh!), but with additional anglers the fishery can be impacted.  Then managers have to adapt to those changes which starts the whole cycle over again.  If we can better understand that cycle and angler behavior then we could be more effective in our fisheries management strategies.  Their work is just getting started, but let me share some preliminary data that I found to be very interesting.  Angler surveys last year documented angler use in excess of 1000 angler-hours per acre of water at Holmes and Bowling lakes here in Lincoln!  That is fishing pressure that is through the roof!  What impact do you suppose that many anglers could have on any fishery?  In addition, they found that almost half the anglers on an urban fishery would not fish at all if that easily-accessible urban fishery was not available to them.  That research will continue in the coming years and I expect there will be a lot more interesting data to come.

Lastly, I was handed a reprint of an article that was published in the September/December 2008 Prairie Naturalist, A Case Study of a Successful Lake Rehabilitation Project in South-Central Nebraska.  Peter Spirk was the author of that paper, and he had two Game & Parks Commission employees as co-authors, Brad Newcomb and Keith Koupal.  They looked at Cottomill Lake on the west edge of Kearney and documented the changes that occurred there with an Aquatic Habitat Rehabilitation project, .  Cottonmill was pretty much a mud-hole before the Aquatic Habitat Rehabilitation project.  They found that bluegill numbers went from 1.5 per frame net prior to the habitat project to 28.3 per frame net after the project.  Largemouth bass numbers went from 8.0 per hour of electrofishing to almost 500 per hour of electrofishing, and channel catfish numbers went from 7.5 per gill net to 34.0 per gill net.  The Aquatic Habitat Rehabilitation project had a dramatic positive impact on water quality and fish populations in Cottonmill Lake!  Angler use at Cottonmill went from 394 angler days in 1993 prior to the habitat project to over 5,500 angler days in 2006 after the project was completed.  Angler catch of bluegill and largemouth bass at Cottonmill was nearly zero before the rehabilitation project, but after the project there were an estimated 11,349 bluegills and 5,187 largemouth bass caught in 2006!  Catfish were one fish that could be caught from Cottonmill prior to the habitat rehabilitation project, but even then the angler catch of channel cats went from 450 before the project to 658 after the project.  The Aquatic Habitat Rehabilitation project at Cottonmill cost approximately $1.5 million.  The U.S. Fish & Wildlife Service has estimated that an angler spends on average $66 per day of fishing in Nebraska.  If you use that estimate as the value of a fishing trip, then the Cottonmill fishery provided only about $26,000 of fishing prior to the habitat project and $367,026 of fishing in 2006 after the project.  If you look at it that way, the value of the Cottonmill fishery following the Aquatic Habitat Rehabilitation project would make up for the cost of the project in about 4 years!

Want another look at what that Cottonmill fishery is now worth?  Take a look at the pictures posted here, .

That is all for now.  I have been spending some time on the ice in the past couple of weeks, stay tuned for reports.  This week I will also be attending our annual meeting of the Nebraska Chapter of the American Fisheries Society (AFS).  AFS is the professional society for fisheries biologists.  We will have a bunch of Nebraska “fish heads” together and I am sure I will hear a lot about other research that is occurring on Nebraska waters.  That means I will have some more science tidbits to share with you!



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