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[chris gadsden]

Chris, I believe chum, pink, & sockeye have very few documented cases of jacks because all these species use abundance of #'s as their main reproductive strategy......just a thought.

Yes that is what I had thought it could be also, I wondered if other thought the same. Thanks.

[JP PATCHES]

The jack question is an interesting one.

Chris, do you think they are born as jacks or do they just turn that way when they see sexy big females heading back to the river, a built in survival instinct?

[bkk]

Clarification on a couple of the Jack theories. First off, all of the pacific salmon with the exception of pinks have Jacks in their population.  Chinook, coho, and sockeye in that order have the most Jacks but it's not unheard of to have chum Jacks. Jacking indeed is a survival technique as it increases the gene flow between broodyears and helps prevent a total loss of broodyears on those years when there are extreme enviromental conditions. That is one of the reasons why pink runs have such a hard time rebuilding after a devasteing flood. No broodyear overlaps.

 Jacking is also a way for "Mother Nature" to ensure that their are always enough males to fertilize the females. If you have Jacks in the population it means that the stock is diverse and this is a good thing as it will benefit the stock in the long run. Jacks when they spawn due not produce Jacks but a normal population. A example of this was back in the early 80's, the Babine Lake sockeye spawning population had, for some unexplained reason, a huge shortfall of adult male sockeye. The Jacks on the other hand were more plentiful than normal and they spawned with the females. When the run returned in 4 years, the population was normal in all respects. So obviously, their there for a reason.

Quote:Another interesting point is that pinks & spring jacks have almost the exact same life history & are almost identical in size. They smolt & return at the almost the exact same time.

Sorry to correct you on this one but it's incorrect. Pink fry emerge from the gravel and go to the ocean immedieatly while chinook will spend upto 1 year in fresh water. Chinook have the most varied life cycles of all the salmon, with some fry going to the ocean upon emergence, some will spend 90 - 120 days in freshwater then head seaward, some will go in the fall and some will go in the following spring. It all depends on where the chinook stock is located. Upper Fraser chinook juveniles generally spend a year in freshwater, Thompson/Shuswap fish 120 days and some of the Harrison fish go upon emergence. There are exceptions to this. The adults also return at different times. In my part of the world chinook are in the river in June and Pinks in Aug - Sept.

[chris gadsden]

The jack question is an interesting one.

Chris, do you think they are born as jacks or do they just turn that way when they see sexy big females heading back to the river, a built in survival instinct?

genetic.

[JP PATCHES]

Sorry Bkk I thought the post was about Vedder Jack chinooks. Veddar whites are originally Harrison stock which do smolt upon emergence. Some rivers have chinook which smolt after 18-24 months of stream residency, but not the Vedder. In the Vedder the pinks & white jacks return at the exact same time (sept/oct).

[The Gilly]

I'm just a dumb fisherman and don't know why.  My guess is that they probably have hightened testosterone levels.  See "horny teens".   My guess on pinks is that they are 2 year cycles and don't have time to "jack".   

Good discussion though.

[Koho]

bkk: Regarding how pink runs have such a hard time rebuilding after floods.  Do you know what year was the flood that weakened or eliminated the even-year lower BC pink run?

Even if humpies did return as jacks, mature females would probably want nothing to do with a trout sized mate 

[The_Roe_Man]

have you seen the size of some of those coho jacks at the vedder.  A couple years ago i caught 2 that were a foot or less in lenght.

[chris gadsden]

I have caught a couple of jack springs betwen 8 and 10 inches. One was on the Fraser while bar fishing and the other on the Thompson.They were not smolts and were caught while the jacks were migrating to the spawning grounds.