What about the Fishery? How will Removal Impact It?

This post is trying to give you the facts about how the existing fish  upstream of the dam and visiting, migratory fish downstream would respond to the dam being removed and the river being restored to its original state.  This is based on scientific and geo-morphologial studies, surveys, and samplings over many years by many experts in their field.

Click HERE to read an excellent summary of the ecological benefit/impact of dam removal.




RIVER FISHERY  'CLIFF NOTES' :

When a dam is removed in a high-quality river system like the Dowagiac, here's what experts expect to occur:

• The average annual temperature will reduce by an average of 2 degrees F.

• The amount of dissolved oxygen in the water will increase year over year throughout the entire main stem.

• The rivers speed, is estimated to increase increase  5%*           (*edited 2/19 from a prior assertion of cfs velocity; Ken's mistake)

• The sediment layer above and below the dam site will begin a constant, daily progression out of the river.

• The accumulated arsenic in the sediment from agricultural runoff will safely disperse and move out, and levels can consistently drop into safe ranges (assuming there are no increases in chemical input, of course).

• As the sediment is allowed to transport as it had prior to the dam construction, oxygen storing gravel will be exposed in increasing quantities each year.

• The river will get deeper on average, especially in areas that used to hold sediment for 83 years.

So What?    What does this all mean? 

It means water that is cooler, cleaner, faster, and  healthier for fish. It means that habitat will be created through restoration--naturally---with gravel and increased biomass and food chain that encourages them to reproduce and grow naturally; with less artificial stocking and plants that utilize state fish hatcheries.


Upstream Fish:

There are native species that live upriver of the dam today, most notably brown trout; which are naturally reproduced to a small extent, but more typically artificially stocked.  By experiencing the above changes, natural reproduction will increase. The upstream fishery will improve.
Those same "upriver" trout will also have the ability to spread throughout the system, unimpeded and have more habitat to roam. (Kinda like "free range" fish, if you will.)

Downstream Fish: 

There are migratory species that visit the downriver portion below the dam. The Dowagiac has never received supplemental stocking of steelhead and salmon. However, the quality of the water, in spite of the dam, is irresistible to them.  Anglers from as far away as Ohio, Indiana, Illinois, and Wisconsin understand this, and visit every year.

Most notably, the predominant migratory species that migrate in from the St. Joseph river are salmon, steelhead trout, walleye, smallmouth bass, northern pike, catfish, and once upon a time, sturgeon !! 

During their annual spawning migrations, each specie will once again be able to transit to the ideal spawning and rearing habitats that the river offers, which will increase in available area as flow volumes begin to remove the sediment blanket, and expose the spawning gravel used to deposit eggs and rear newly hatched fry.  

Rivers of a similar quality have seen the above occurences over and over consistently across the U.S.  More locally, restored rivers have documented  fish populations (in this case, rainbow and brown trout) before and 4 years after-- dam removal and documented a 4x-6x increase in trout and salmonid populations.   There is a post in this blog referencing an MDNR study which sites this research from a removal and restoration that occured in Stronach, Michigan on the Pine river. Another similar result is summarized in the film posted here entitled "Preparing for the Future"

TRUE OR FALSE ?

"Trout and salmon cant live together. Salmon invade, and compete for habitat and the salmon cannibalize the trout. The population will get ruined."

Answer:    FALSE.    FALSE.   FALSE.     FALSE.
Contrary to popular angler belief, which to date is unsupported by any data--trout and salmon can and do co-exist successfully. There are  hundreds of rivers in the Midwest, Pacific Northwest, and Mid-Atlantic regions that point to this; which thrive and have inter-mingling salmonid species. Right in our own area, there are numerous destination fisheries in Michigan that receive thousands of visiting anglers who pursue them with flyrods, bait, plugs, spoons, and spinners.One well known river that contains trophy populations of all species is the Pere Marquette.  We should also recall that brown trout, a specie of concern for many supporting this argument, are an artificially planted species (just like salmon) that were dumped put into Michigan waters after being shipped over from Germany.  

In fact, a club you may have heard of, Trout Unlimited, is one of the largest, best organized proponents of dam removal to improve trout habitat and water quality in general.

(The below 2 pp. added on 2/19)
Hear us out:   You may not "want" the trout and salmon to mix. Thats OK. That is a preference of seeing species separated. But it is UNTRUE to say they can't live together and that salmon or steelhead are invaders that ruin populations. For roughly 10 weeks out of the year, salmon show up, drop eggs, and die.

People who make these contentions have either not observed the other flourishing fisheries in Michigan, or have ignored obvious, visual evidence.  By the way: the hundreds of thousands of salmon eggs and thousands of parr provide a new and extremely valuabe and easy-to-catch food source for trout. Trout in some river systems put on 50% of their weight gain from gorging on these new sources.

The rotting carcasses of salmon are excellent sources of material eaten by various nymphs and crustaceans like crayfish; another vital food source for trout.  This, as you may be concluding is something known as the "food chain". And it works pretty well, we think.

Show us the studies that conflict with documented fisheries management practices by expert in biology--and we will publish them.

Don't believe it?    GOOD!
 
Click here to verify that TU loves dam removal to improve trout ecosystems.


In summary, the fishery stands to derive immediate and measurable benefit to a great degree by river restoration and dam removal. More fish, more naturally reproducing fish, fish that can withstand the extreme high and low temperatures of Michigan's weather, and less dependence on state-sponsored planting of hatchery-reared fish.

TRUE OR FALSE:

 "Sediment is BAD. Gravel is GOOD. Sediment is horrible, its awful. It needs to be removed from the river to expose gravel and let the water be crystal clear and let natural vegetation grow. Sediment robs carbon dioxide and creates a hostile substrate. The river needs to flush all the sediment downstream and out of the river"

Answer?    FALSE.

Too much sediment in one place can be harmful. Too little sediment in one place can also be harmful.  Optimal river health seeks a balance of sediment across the entire length, and will release 'some' un-needed sediment naturally.

Think of a river-bed  like a brick wall that lays at a 20 degree angle. Wood, rocks, shells, and other substrate are the bricks. Sediment is like the mortar.  If you remove too much mortar, the rain and water will move across the bottom with less resistance and will wash away other underlying materials that are supposed help support the wall and keep it up. The wall, with no mortar --settles and shifts very rapidly. This process eliminates what is more commonly known as "  riffles"".



DID YOU KNOW:  In dams that are removed, the sediment that is trapped and collected, is sometimes loaded into dump-trucks and brought to DOWNSTREAM river areas to help repair/reinforce areas that have been 'sediment-starved,' and eroding too rapidly.

  In those areas, there wasn't enough mortar in the brick wall, and things beneath and to the sides of it were getting washed away (eroded) too quickly. So you see, the proper balance of sediment prevents, not causes the problems.




Still don't believe us?    Whatever.

Take the challenge:   Pick up the phone, contact the Michigan Department of Natural Resources to confirm anything above, or to ask  further questions. They have been recommending dam removal and river restoration to improve the fishery.

They are expecting your call !


Jay K. Wesley
Southern Lake Michigan Unit Manager
DNRE
621 N. 10th Street
Plainwell, MI 49080
269-685-6851  Ext.  117













Thanks!