Good Read, Intresting Data

[FireFish]

Check out this article. Some of the early findings are surprising. 40% Mortality rate of juvenile's is interesting...
Now if they can implant enough, and track them until they reach Adult Status, then gather the numbers of what is ending up in Alaskan & Canadian COMMERCIAL NETS... :rolleyes:
They have done some of that in the past, but on a very small scale...

http://www.thenewstribune.com/news/environment/story/553257.html

FireFish...

[Chinook SSSF]

Great reading, and learning. Thanks for posting :)

Surprising mortality rate.........

[scudrunner]

Here are some very interesting and insightful responses posted regarding this article on another forum:


Freespool wrote:

I wouldn't break out the party favors just yet, this so called study hasn't passed the peer review smell test.
Here's what I found so far.

http://www.fpc.org/documents/memos/186-08.pdf


Our overall conclusions are:
•
Acoustic tags of the size range and tag burden used in the Welch study are likely to
affect fish behavior and survival.


•
The acoustic tag/POST array is of questionable utility and application for
monitoring juvenile salmon and steelhead migration characteristics including
survival.


•
The Welch et al analysis and conclusions are questionable because they rely on a
wide range of disparate data sets over different time periods, different tag types and

require implicit assumptions that are not identified by Welch et al.

RiverMan wrote:

There is decades of research verifying the mortality of juvenile salmonids as they migrate down various tributaries and through the mainstem dams. One example I am familiar with is recent PIT tag data for the Walla Walla Basin that showed about 70% mortality for juveniles moving down through the Walla Walla River and to the first mainstem dam (McNary Dam).

There may also be other explanations for why juvenile fish mortality goes up in the ocean:

1. Maybe the 40% that died in the ocean was the result of the cumulative stress related to migrating through the dams.

2. Maybe the accoustic tags make it easier for predators to key in on the tagged fish.

3. Maybe the tags themselves caused a delayed infection for the tagged fish or made them slower and more prone to predation.

We still have much to learn and one study comparing the Fraser to the Columbia does not prove our mainstem dams are without passage problems.

I'm wondering what the range of the tags is........how close to they have to be to the receivers?
So, I think that there are way too many variables to make any sound (no pun intended) and scientific conclusions.

Cheers

[FireFish]

Lots of good info and rebutle to look at there. I look at this as another study in the works, trying to understand what is going on with some of our fisheries at certain levels. If funding is available and people ar willing to build sound scientific data on some of this stuff, more power to them. One thing I always try to consider is, where is the funding coming from and who has what to gain by the results. Oh, I guess that's actually two things...:rolleyes:

FireFish...

[scudrunner]

If funding is available and people ar willing to build sound scientific data on some of this stuff, more power to them. One thing I always try to consider is, where is the funding coming from and who has what to gain by the results.

One consequence of biased funding is the NPMFC studies and ruling on the halibut of South East Alaska... presently, the commerically wasted bycatch from trawlers is greater than the entire sportfish harvest, and yet, it is the charter boats that are restricted! However, if memory serves me correctly, the commercial harvest level was reduced this year. Nevertheless, the charters' limit was reduced by 50% in some areas:confused: Supposedly, all of this is to control the "unchecked growth" of the charter industry.

So, who has what to gain? Who is funding the studies?

That being said, I have the highest regard for the bio's in the field. I truly believe that they are doing their best to supply sound scientific data. However it is what happens to that data and how the results are slanted that concern me.

[FireFish]

So, who has what to gain? Who is funding the studies?

That being said, I have the highest regard for the bio's in the field. I truly believe that they are doing their best to supply sound scientific data. However it is what happens to that data and how the results are slanted that concern me.

I couldn't agree more...

FireFish....