Dam!

[LMarshall]

Satoshi, New England sounds similar to Japan in terms of the number of dams on small streams. Most were built to power saw mills and gristmills over a hundred years ago, or to divert water for farm ponds and agriculture. During the industrial revolution many more were built; it's amazing how many small factories dotted the country side wherever good water power could be found. I've often been surprised to find old mills on small rivers and streams in the middle of nowhere. A lot of these dams are starting to come down as they've become structurally unsound over the years.

Here in New England all the dam construction which took place on major rivers has been disastrous for migratory fish like Atlantic Salmon, Sturgeon, and herring. Dam construction on smaller rivers and streams has played a major role in habitat loss for brook trout.

In Southern New Hampshire where I grew up a dam was removed on a small river (the Souhegan in the town of Merrimack), opening up 14 miles of river to the much larger Merrimack River, probably for the first time in at least 150 years. I don't know if any effects have been felt yet, but there have been additional proposals to remove two more similar dams on the Souhegan in Milford NH, opening up another 6-7 miles of river. It's late now so I'll look up some info on the dam removal projects on the Souhegan later.

Edit: couldn't resist googling the dam removal in Merrimack - http://www.nmfs.noaa.gov/habitat/restor ... amcam.html

[Satoshi]

In Southern New Hampshire where I grew up a dam was removed on a small river (the Souhegan in the town of Merrimack), opening up 14 miles of river to the much larger Merrimack River, probably for the first time in at least 150 years. I don't know if any effects have been felt yet, but there have been additional proposals to remove two more similar dams on the Souhegan in Milford NH, opening up another 6-7 miles of river. It's late now so I'll look up some info on the dam removal projects on the Souhegan later.

Edit: couldn't resist googling the dam removal in Merrimack - http://www.nmfs.noaa.gov/habitat/restor ... amcam.html

LMarshall,
Wow! This is great! I've just looked at this noaa page and the movie. I wish this they'd also do this in Japan.

[wb4tjh]

I've fished the tailwaters of the White River, Little Red, and Little Missouri Rivers in Arkansas since the mid 1960s. Now I have just moved to SW Missouri, and those same waters are a lot nearer than they were before.

[Brooktrout]

Satoshi-
it is interesting that you mentioned the removal (or slated to be removed??) dam on the lower elwah river in wa state. a buddy of mine used to fish that lower section and he said the salmon used to just stack up below the dam. it is, or was, owned by warren buffet's berkshire-hatthaway company. i hope they have torn it down. they need to do that in a lot more places here in the west too.

[pszy22]

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[Satoshi]

pszy22 ,
I looked at the link. I am impressed they are estimating the catch rate of fish after the change. This seems to be a nice way when the removal is not an option.

Brooktrout,
Talking about the dam removal, I found an exciting news story yesterday; They decided not to relicense a large hydroelectric dam in Japan. In other words, they are going to remove it. It would be the first time in the history of this country to destruct such a large dam. The dam is located in a warm region (Kyushu), and the removal would not have any effect on the population of landlocked yamame in the headwater of the river, but the river does have an anadromous fish, the ayu, which is the most popular freshwater gamefish in this country. I'm sure the removal will have a strong positive impact on the population of the fish. So, I'm excited about the news, and I hope they will do this to other dams in northern part of Japan. (Usually, there is no good tailwater fishery of trout below dams in Japan, with a few exceptions.)

[luredalive]

JEEZ........that picture of the Hoover Dam and bypass.............you could'nt make it up,it looks unreal!!!!!!
AMAZING

[Zac Sexton]

Well, guess I can share this bit of information I have known but not often shared, about dams and salmon/steelhead smolts on the Columbia River: A buddy of mine used to be a fisheries tech. for the USGS, and collected information on radio tags implanted in Steelhead and Salmon smolts--some were wild, some were hatchery fish. The transmitters gave the USGS data as to the migration of the smolts, which they collected to monitor how they passed through the Columbia River system, including dams and fish ladders.

One incredibly interesting fact of the study that my friend shared with me was that hatchery smolts stayed high in the water column during migration. What this means is they haven't adapted a fear of airial/surface predators (birds, man, otters, etc...), and their habit is to be in the surface to look for feed (learned behavior from most hatcheries {there are exceptions...}). This puts them in a better position to be caught in nets for transport in the trucks used by federal and state agencies to transport fish through the dams; keep in mind, this is downstream migration of juvenile fish, looking for the ocean to get big in. They also are more able to make it over the spill-ways in to fish ladders, which are at the top of the dams.

Native/wild fish, on the other hand, tend to stay deep in the water column. This reduces predation on the overall population, but leaving them to die trying to find their way to the ocean, because they also aren't as available to catch in nets for transport, nor able to reach the spill-overs to the ladders.

Them there are the facts. It also doesn't tell my complete feelings on dams--which would be a novellete if written out. But, I do not agree with dams that block fish migration. We have other ways to ship and make electricity, as well as store water and irrigate. But, it's also very clean electricity, and a lot of it.... The Columbia River used to have the largest salmon run in the US, as well as the largest-sized strain of Chinook Salmon in the US/N. America! Used to....