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Message Subject: Hydro Dam removal. Good or Bad for reproduction?

walleye express

Posted 3/12/2010 1:02 PM (#88949)
Subject: Hydro Dam removal. Good or Bad for reproduction?

Member

Posts: 2680

Location: Essexville, MI./Saginaw Bay.

Thought I would share this recent post from my board. Along with mine and my DNR buds answers to it. It has to do with power dam removal and what impact pro or con it might have on natural fish numbers.

Question:
The Chesaning Dam on the Shiawassee River is now gone & replaced with a series of rocks that allow fish passage. Approx. 37 miles of river spawning habitat is now available upstream of Chesaning and it will be the first time in 150yrs that fish can access and spawn in these headwaters. If you had something to do with this project, I'd like to Thank You. It seems like a step in the right direction for a population of river spawing walleye and for fish and wildlife in general.

Capt. Dan, or anyone that can answer, what does this change mean to our fishery. Is this 37 miles of the Shiawassee River system a substantial improvement ?

My answer:

IMO that would depend largely on rather the bottom strata above this dam is conducive to good spawning conditions that would determine the best results. Walleye are broadcast spawners and do not fan gravel or make nests for their eggs. You will occasionally see tail and anal finns that show some wear on walleyes after the season re-opens, but that is not from fanning nests, but comes from resting on or having close contact with the bottom during the spawning cycle. Walleye in most cases hover just above the bottom and let their eggs go and fall into cracks and crevasses of what is ideally baseball size rocks. The male does the same with his milt. If these conditions are ideal in any of the new waters now open upstream above this removed dam on the Shiawassee, the walleyes will find it and take advantage of it. The survival results then may depend on other variables like available food in the form of Phi-do or Zooplancton, as well as weather conditions and how rough the smolting process is back down the river to the bay.

My DNR buds answer:

First I'd like to say that access to spawning grounds for our fish is a critically important issue in Michigan and the Great Lakes. This is not just important to walleye but many other species including lake sturgeon. Michigan has thousands of dams and spillways that impede fish migration. They are like clogs in one's arteries interfering with essential life processes. Some of these dams serve important purposes like flood control and hydroelectircal production but many don't and are useless. Most are privately owned.

Dam removal is the preferred option when possible. Its expensive however and many owners elect to just let dams sit. More government agencies are trying to work with dam owners on removal or fish passage opportunities. These programs need more funding. Fish passage designs (like the rock ramp at Chesaning) are the next best option (if removal isn't an option). Their ability to pass fish, however, is not certain. Fish are particular things and they have to have just the right conditions to navigate obstacles. Proper design is critical to a successful fish passage project.

The goal is to get fish up to spawning grounds and hopefully improve (increase) reproduction. More reproduction should hopefully mean more fish eventually for our populations and fisheries. Its hard to predict how much benefit might be realized by opening up these new miles of spawning habitat. It really depends on the quality of the spawning habitat and the distance to the nursery grounds where the fish fry need to reach. If the habitat is of high quality and the not too far from the nursery grounds, the benefit should be great. If the spawning habitat is poor and far away, then the benefit might be low.

Part of the problem with fish passage (as opposed to dam removal) is that the reservoir behind the dam remains. This means that much of the river is lake like and not river like. Needed is flowing shallow water for spawning, not another muddy, silty slow water impoundment. Remember that locations for dams were often selected for he fastest water (most gradient or slope) so the best habitat is usually under the dam and immediately behind it. Consequently fish passage alone may not have as much benefit as dam removal. I can say that one or two removal projects (or maybe fish passage) in some key locations could greatly increase fish production for some species in some systems.

This is a much more cost efficient means than trying to just stock more fish. Plus wild produced fish are almost always better surviving and performing than hatchery fish. Evaluation of what has been accomplished with dam removal and fish passage projects is an important follow up part of any effort. I think I heard that there is a fish passage evaluation planned for the Chesaning Dam ramp so maybe in a couple years we'll know more.

Edited by walleye express 3/12/2010 1:10 PM

Viking

Posted 3/12/2010 1:40 PM (#88950 - in reply to #88949)
Subject: RE: Hydro Dam removal. Good or Bad for reproduction?

Member

Posts: 1314

Location: Menasha, WI

Somewhat related...National Geographic Channel had a special on the engineering of a dam removal in Oregon. Pretty cool process

http://channel.nationalgeographic.com/series/break-it-down/all/Photos#tab-Videos/06313_00

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