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Author Topic: Jacks, Jennys and mini-jacks  (Read 2391 times)

VAGAbond

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Jacks, Jennys and mini-jacks
« on: May 07, 2010, 07:38:54 AM »

An American sport fishing publication reports that the percentage of jacks in the returning chinook runs has surged in recent years from typically 3% up to 28% and higher.  This has resulted in serious overestimation of the subsequent returns of mature fish.   This phenomena is  most evident on the Columbia but has been noticed in other rivers, even as far away as the Kenai in Alaska.   Nobody seems to have any idea why this is occurring but it is apparently most evident in hatchery enhanced runs.

Question:    I have read comments on this site about lots of jacks in our local rivers.    Are we also seeing the subsequent runs of mature fish come in well below expectations based on the count of jacks?
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adriaticum

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Re: Jacks, Jennys and mini-jacks
« Reply #1 on: May 13, 2010, 09:58:55 PM »

This is a very good question.
It is probably safe to assume that any river near populated areas is experiencing lower returns of fish. But long time anglers like Chris can paint a more accurate picture.
Some rivers that have hatcheries might be keeping the numbers up, but the wild fish ("untouched" and "unmanaged" by people) are definitely on the decline.
Marine bioligists are trying to understand what is going on, how much of the decline is caused by people and how much by natural factors.
Some say lot of it is due to over fishing and declining productivity of the oceans. Others believe that warming is causing some of it.
All the damms and growing population isn't helping either.
I don't really know as I haven't fished for salmon for a long time and have nothing to compare to, but I have certainly caught a lot of jacks in recent years.
I don't keep any adult fish at all.
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