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Yes...their youth. Jacks are precocious males...returning a year early. Its an evolutionary advantage that helps ensure species survival.
 

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Hope this helps. from http://www.spsseg.org/articledetail.asp?ID=2

The Unappreciated Jack
By Richard M. Johnson

The jack salmon is looked at as either a fun fish to catch on an ultra light spinning rod, or the failure of a perfectly good fish to reach it’s potential. When I say “jack”, I’m referring to a precocious male salmon that decides to grow up in a hurry. It spends one year or less in salt water before returning to fresh water to spawn like the big boys. You may wonder why they mature so quickly and are they successful spawners? The answer to the first question is that this might be nature’s way of spreading out the genetic contribution of a particular brood year over several years. In the case of chinook salmon, the dominant year class is the age four group. However, some return at age two (jacks), some at age three, and there are even a few five year olds (six year old chinook are rare in the south Puget Sound watersheds). An environmental roadblock such as flooding or poor marine survival might limit the number of spawners in a given year. Fortunately, the jacks would have returned before the problem arose (take El Nino years as an example, when adult salmon, especially coho, were hard hit due to poor feeding conditions). As to how jack salmon fare in the competitive world of reproduction – they have developed a special tactic that we know as the “sneak attack”. While the big brutes are jousting for the right to sire the eggs of an unsuspecting female, the jack waits in the shadows and races in at just the opportune moment to add some of his own milt to the pot. In spite of its diminutive size (one to four pounds), the jack is governed by the same biological clock as its bigger adversaries. It dies shortly after spawning, and its carcass decomposes, putting important nutrients back into the stream.


Despite the importance of jacks in nature, fisheries managers are constantly trying to figure out ways to prevent ******* (j-acking) in hatchery stocks. More jacks means fewer adults back to the rack for spawning (and fewer adults available for harvest). There appears to be a nutritional link to precocious maturation such that the faster the growth of juvenile fish, the higher the ******* rate. It follows that salmon that go through “extended” rearing in the hatchery, where they receive plentiful, high quality rations, tend to have a higher rate of ******* than fish that rear in the wild the same length of time. High concentrations of forage fish available to young salmon in the marine estuary or nearby vicinity could result in ******* due to the rapid growth experienced by the voracious feeders. Genetics, as well, plays a role in determining precocity. More jacks in the spawning population results in more jacks in the offspring. Generally, about 3 to 10 percent of the naturally produced males mature as jacks, depending on species and location.

In spite of the fact that a jack will never attain the size to make it a prized sport fish
or a brawny super-stud on the spawning ground, a good showing of jacks is often used as a predictor of a good adult return the following year. That makes them worth their weight in gold.

[ 06-24-2003, 09:17 AM: Message edited by: fish_on ]
 

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never caught one before but they sound like fun.
 

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anyone else notice a lot of summer jacks being caught? i caught about a six pounder on sat, looked like a football. some of the best fish ive eaten.

d
 

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Wow fish_on that was very informative... thanks for taking the time :cheers:
 

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Discussion Starter · #8 ·
up on the main salmon in idaho i saw LOTS of jacks being caught..i caught one
good thing i tossed it back
 

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Thanks for the info fish_on. Very informative :cheers:
 

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Speaking of Jacks...anyone else watching the summer chinook jack count over Bonnie? It is tracking well ahead of last year. Currently just over 5000 with a week to go in June. :dance:

Last year had a total summer jack count of around 8000. As far as estimates go, they use a 20:1 (jacks to adults) as a forecast for the next years return. I have been surprised how accurate this is on the Columbia. The numbers are close or just under the actual return. :wink:
 

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Originally posted by fish_on:


Despite the importance of jacks in nature, fisheries managers are constantly trying to figure out ways to prevent ******* (j-acking) in hatchery stocks. More jacks means fewer adults back to the rack for spawning (and fewer adults available for harvest).
<font size="2" face="verdana,arial,helvetica">At least in Oregon it is now common practice to spawn a certain percentage of the returning jacks. I was told that it had something to do with preserving the genetic makeup of the stock.
 

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Discussion Starter · #13 ·
we cant say ******* on here?
you know the filters are too strong when you cant say j-a-c-k-i-n-g

[ 06-25-2003, 01:20 PM: Message edited by: BonkBonkBonk ]
 

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Dev, the Columbia River section of the Oregon regs say "Open to adipose fin-clipped jack.....". Guess you can't retain wild jacks. Also, I didn't know this but, salmon are considered jacks when they are between 15 and 24 inches for chinook and between 15 and 20 inches for coho. Jacks under 15 inches is considered trout? :whazzup:
 

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[ 06-25-2003, 03:20 PM: Message edited by: Miss B Haven ]
 

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Page 23 of the current regs under trout states that "Salmon under 15 inches are considered trout, except coho salmon, which are considered salmon regardless of size." Not that I would keep one of those baby fish. :rolleyes:
 

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Bonkx3, why did you toss it back? You should keep all the jacks you can. You don't want them spawning and making more jacks! You want that hen to spawn with a nice 40 pounder, not Beetlejuice... By the way, you usually can only keep jacks above the Astoria Megler Bridge. I think they assume that a jack might come into the estuary below the bridge and then return to the ocean to grow a few more years so you can't keep them until you get above the bridge.
 

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I caught a nice jack last Saturday on the Columbia. It was 23 3/4 inches and weighed almost 8 pounds. Best eating fish I ever had!!!
 
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